Technical info.

my projects

noreply@blogger.com (alit76) — Fri, 07 Sep 2007 14:35:00 +0000

Mesin lemang.(machine to produce lemang)

I'll show you how i do it in my next posting.this is one of several projects that i did with my collegue at GiatMARA PJU.
this project has won the first place in MARA innovation and invention contest and currently we are trying to commercialize with patented rights on the market through the entrepreneur programmed by GiatMARA Malaysia and in hand several prospect have been made.

Three piston model steam engine my version

the actual design for this engine was actually taken from another website but i've made some significant changes to suites my taste and unique especially the turbine fan that's mine .
most of the parts were made of aluminium and it can run on steam or air compress.
if you want the design, you can email me or if you already made one similar to this, share it with me so we could exchange ideas or info either way,you can ask me anything.

there's more to come........VISIT AGAIN

The Key to Controlling Your Machining Process

noreply@blogger.com (alit76) — Mon, 03 Sep 2007 12:00:00 +0000

Over the past decade high velocity and hardened metal machining has become fairly commonplace in the die/mold, aerospace and medical component industries. The machining process has not changed much, but the cutting tools required have changed dramatically.

Tooling Requirements
Efficient high-speed and hard machining of molds, dies and other components requires tooling that can take the heat of the higher surface speed. The tooling also must have the edge preparation to hold up to the forces and abrasion of higher speed milling.

Coatings
The most important thing to take the heat is in the coatings. TiAlN (AlTiN)-coated tools are best for steels over 40 HRc or running over 800 sfm. There are many different variations of each of these coatings since there are many different companies that coat tools. Trial and error is the only way to decide which one is better. Most manufacturers of cutting tools perform their own tests on these coatings, but some do not test specifically for high-speed and hard metal machining.

High feed insert. Images courtesy of Millstar and Commercial Tool and Die.

Look for a cutting tool manufacturer that performs extensive testing in hardened metal to help develop the best coatings available. AlTiN coating is still the best choice and in the future there may be the possibility of including Si (Silicon) in the coating mixture. As the machining center spindle rpm increases the coating and carbide combinations must be able to keep up with the higher heat that is being generated. The addition of Si will create a very high oxidation resistance that will allow the coating to work at temperatures of up to 1100oC.

Geometry
The geometry on the tool also plays a big part in controlling heat. The geometry of the cutting tool must allow for chip removal in order to take the heat out with the chip. There is a new geometry of ball nose insert available, which has a three-dimensional helical grind that allows for smoother cutting, less vibration and better chip evacuation, all of which reduce heat generation. These new geometries require a new machining approach to effectively utilize the tool. Higher rpm and feedrates with shallow depth-of-cut are typically required to maintain chip flow and heat.

When deciding on the geometry of the cutter there are a few guidelines to follow. For example, always check the accuracy of the tool you want to use. Diameter, radius and runout are all things to consider. The more accurate the tool, the more accurate the part will be. Maintaining lower runout will generate a better surface finish, accuracy and lengthen the tool life.

P20 material being machined with a high feed insert tool.

A two-flute ball nose cutter with a large core diameter seems to be best suited for complex 3-D milling. More flutes are not recommended, as the extra flutes hinder chip evacuation. Also, if you are cutting on the tip of the tool there are only two flutes at the tip, on a three-flute tool there is only one flute at the tip.

Insert Technology
Insert technology for die/moldmaking and general machining applications has been enhanced to a level that it can perform most operations without fail. Many operations can be performed with insert tooling, especially in medium to large cavities and cores, since the diameter of insert tooling available fits well into this category.

Insert tooling—from diameters of 1/2 inch (12mm) and larger—works very well for roughing and finishing applications. The smaller insert diameters are designed mainly for finishing applications and some lighter duty roughing.

Solid Carbide Tooling
There are still certain applications areas where solid carbide tooling has advantages. The most obvious time to select solid carbide tools is when the diameter is less than 1/4 inch (6mm). Insert technology has not been developed for the smaller diameters.

One of the newer processes called trochoidal milling is another application for choosing solid carbide end mills. Trochoidal milling is an application that is used mainly for slot machining, but some CAM software developers are using this application for cavity milling as well.

This process entails machining with a large depth-of-cut and very small step over. The machining motion is a very smooth arcing loop cut that moves forward by an amount roughly equal to the step over amount for each loop. A solid carbide end mill is used because it has multiple flutes to maximize the feedrate. Typically this tool also is a high helix tool. This allows for very smooth cutting and the ability to create very good surface finishes. A drawback to this milling strategy is deflection if the tool is long.

Solid Carbide Shanks for Insert Tooling
The old theory that the extension length to cutting diameter ratio plays a deciding role in choosing solid carbide versus insert tools is now being challenged with the introduction of new solid carbide shanks for insert tooling.

3-D helical grind on a ball insert.

There is now very little reason to use solid carbide end mills in diameters exceeding 1/2 inch (12mm). Before this technology a steel shank toolholder did not have the rigidity required to aggressively machine with long tool extension. Now a carbide shank toolholder with a relatively inexpensive insert can be used in these applications, rather than using a more costly solid carbide end mill. Additional advantages of insert technology include flexibility, repeatability and longer reach.

High Feed Insert Tool for Roughing of Soft Materials
Milling of pre-heat treated materials can be performed quite easily with today’s cutting tools. A new insert tool for roughing of soft materials has been developed that offers a faster alternative for roughing. This high feed tool geometry is designed for high rpm and high feed machining with a relatively shallow depth-of-cut.

Case Study
An actual cutting example that was run with this geometry was as follows:

Machine=FPT Dino five axis
Maximum spindle speed=10,000
Diameter of tool=1 inch
Depth-of-cut=.035
Width-of-cut=0.75
RPM=3800
Feedrate=310 inches per minute
Tool extension of 4 inches
Oil mist coolant

In this application the customer did not previously rough on this machine as the spindle torque is limited in the lower rpm range. By machining at 3800 rpm it was possible to get into the power band of the machine spindle.

Using a 1-inch diameter tool also allowed for roughing closer to net shape than was previously performed with a larger diameter tool.

Finishing
The cutting tool, machine tool and coating combinations now available can allow finishing of most die/mold materials with cutting speeds in excess of 1200 sfm. Some finishing operations are even performed at 3000 sfm with great success. Since the cutting speed is higher, the feedrate also is very high, which offers the opportunity to decrease cycle times while also increasing the finish quality.

Mold that was machined using high-speed machining (P20 material).

The key to success is making sure the semi finish passes are as close to net shape as possible so the finish tool does not have drastic changes in the amount of material being removed. More consistent stock removal in finishing will create more constant cutting forces, which will offer more predictable tool life and can shorten cycle times. Picking off small radii before finishing the main shape also will help increase tool life as well as enhance the surface finish and allow for more unattended machining.

Finishing of most die/mold materials is performed with air blow or oil mist. At the high cutting speeds liquid coolant can fracture the carbide tool due to the heat in the cut and the cold temperature of the coolant. Oil mist will provide the best surface finish while also increasing tool life.

Summary
Controlling heat is the most important factor in high-speed and hard metal machining. If you can control the heat you have taken a major step in controlling your machining process.

Hard milling applications put high demands on the toolholder and cutting edge, and require certain adjustments to milling parameters. Fully hardened material is harder to cut and the cutter will develop more heat in the cut. By using ball nose tools wherever possible, the detrimental influence of heat can be minimized.

In hard milling the depth-of-cut and step over are reduced to minimize heat. Due to the additional chip thinning effect caused by the shallower depth-of-cut, the tool can be run at a higher feed per tooth (fz). Toroid tools, bull nose tools and square tools also may be used in hard milling operations, but the sharper the corner radius, the less “heat-defying” the tool is.

Faster Cavity Roughing

noreply@blogger.com (alit76) — Mon, 03 Sep 2007 11:59:00 +0000

These days, domestic mold and die shops make it or not based largely on how fast they can hog out tool cavities. Faster cavity roughing gets the whole tool set out the door sooner, enabling you to compete better against offshore shops while still preserving your margins.

So when you find a way to double or triple your cavity roughing rate, you jump on it.

That’s exactly the case at B&J Specialty (BJS) in Wawaka, IN, which focuses on larger mold and die sets for the appliance and automotive industries. Today they’re roughing hardened A-2 die stock twice as fast as before. Moreover, they’re hogging out cavities in wrought H-13 and M-4 mold stock three times faster.

B&J Specialty’s cavity rough-milling is running a whole lot faster after retooling with Ingersoll Chip Surfer replaceable tip mills. Throughput rose sixfold on hardened A-2 steel and more than tripled on wrought H-13 and M-4. Photos courtesy of Ingersoll Cutting Tools.

BJS process engineer Scott Sizemore had a hunch he could be roughing faster than 80 ipm if only he could find a cutter able to stand up. After all, their Makino V 550 vertical mill with a 20,000-rpm spindle had higher feed to spare. But whenever he turned up the feed, the solid carbide ball nose mill he was using—at $90 a pop—dulled out in just minutes. “Shows you what a fresh set of eyes can do,” says Sizemore, who led the change.

First Impression
The fresh eyes belonged to Mitch Bair, a representative from Ingersoll Cutting Tools recently assigned to this account and looking to make a good first impression. Sizemore showed him the cavity roughing operation with the ball nose mill and challenged him to come up with a better way.

“It was one of our bottleneck operations, so any improvement here would benefit the whole enterprise,” explains Sizemore. “If we go to the trouble to re-tool, we’d better make it count.”

After studying the operation, Bair suggested that a recently introduced Ingersoll Chip-Surfer high-feed bull nose cutter with replaceable tips would improve the roughing rate on soft stock by at least three to one and reduce tooling costs to boot. For roughing the hardened A-2 stock (Rc 60), Bair recommended an Ingersoll toroidal cutter, projecting at least 60 percent higher throughput.

Ingersoll high-feed bull nose cutter hogs out cavity at 700 ipm in wrought mold block at B&J Specialty, up from 80 ipm with solid carbide ball nose mill. Despite the higher material removal rate, edge life per unit of material removal more than tripled.

Tests Point the Way
Then he brought B&J the two tools to test on their own, with suggested settings. For roughing the soft wrought H-13 and M-4 steel, he suggested 6800 rpm, a 600-700 ipm feedrate and a slightly shallower depth-of-cut (DOC): 0.020 in. vs. 0.050 in. with the ball nose mill. For the toroidal cutter on hard A-2, he suggested 200 ipm/0.012" DOC, or twice the feed and three times the DOC as before, at the same 3750 rpm as before.

The next week, Sizemore tested the high-feed bull nose Chip Surfer at 600 ipm/0.020 DOC on the wrought mold stock. Spindle speed was 6800 rpm, unchanged from before. The tip was still sharp after an hour in the cut, which was how long the old solid carbide cutter has lasted—while cutting at only 80 ipm. He changed the tip anyway, a 20-second job with the Chip-Surfer shank still chucked in the spindle, and started right up again. With in-spindle tip changing, there’s no downtime touching off or reprogramming datum references.

Doing the math, Sizemore concluded that he had found the solution for one bottleneck operation. The bottom line: 3.3 times faster material removal on wrought mold stock and three times longer service life of a cutting tip costing about 40 percent less than the cutter it replaces. The time saving for edge changing—20 seconds from STOP to START vs. five minutes before—was simply icing on the cake.

Tests with the toroidal cutter on Rc 60 steel were just as conclusive.

The cutter lasted a full hour in the cut, the same as before, but after feeding 4.5 times faster for the entire hour. The toroidal cutter made chips at 3750 rpm/175 ipm/0.012" DOC, vs. 3750/100/0.004" before.

“While even a small percentage gain in rough-milling throughput would be important, here we’re talking order-of-magnitude increases, on both the wrought and hardened steels,” says Sizemore.

Pushing the Envelope
Not surprisingly BJS has standardized on the Ingersoll cutters for all their rough and semi-finish milling of mold and die cavities. But Sizemore didn’t stop there. He inched up the speed settings over those used in the validation test. Result: BJS now feeds the Chip Surfer high-feed bull nose cutter at 700 ipm and the toroidal cutter at 200 ipm with no loss of tool life or surface finish quality.

Ingersoll rep Mitch Bair reviews results with B&J Specialty’s Scott Sizemore. To make a good first impression when he was assigned the B&J account, Bair spotted the way to debottleneck the moldmaker’s rough-milling operation.

“We’re literally roughing 3.5 times faster and finishing six times faster than before with similar gains in edge life per unit of material removed,” says Sizemore. “In effect, eliminating this bottleneck has increased capacity of the shop as a whole, and enabled us to quote better deliveries. That gives us a key competitive edge over offshore shops ten thousand miles away that use lower technologies. We also can quote price with a sharper pencil and still maintain margins.”

Geometry Matters
Higher cutting rates with the Chip Surfers stem directly from their advanced geometry. First, the tool silhouettes are more straight-sided and cylindrical than spherical as with ball nose cutters. The pitch radius, and therefore the surface cutting speed, is more uniform over the entire cutting surface. Surface speed doesn’t approach zero as it must near the nose of a ball nose mill. Next, a robust sweeping radius capitalizes on chip thinning for faster removal on straight cuts. Generous corner radius and backdraft combine to facilitate cleaning out corners and minimize cutting forces. Finally, the tough alloy shank withstands shock and side deflection better than brittle solid carbide cutters.

And for milling the hard steels, the Ingersoll toroidal cutter boasts some of the same design differences over ball nose mill cutters, and more. The toroidal cutter also features six flutes instead of four, permitting 50 percent higher feeds without increasing cutting forces per flute. And again the radius is essentially constant over the entire cutting surface—keeping surface speed more uniformly optimized. With the shallow cuts characteristic of milling hard metals, this is a tremendous advantage.

The tool design also recognizes that efficient cavity milling is essentially side milling, which involves higher lateral forces. The alloy tough shank handles lateral forces that would snap off a solid carbide cutter.

STEP NC—The End Of G-Codes?

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 14:23:00 +0000

Imagine this: You call up a Web browser on the PC-based CNC at your machine tool. You go to a certain Web site. From a menu on the home page, you select one of the databases it accesses. A 3D image of a workpiece comes up. You click on an icon in the task bar and check a few parameters and default settings on a pop-up window. Then it's a click on the CYCLE START button. The spindle motor starts to whir, axes begin to move, coolant spurts out and chips are soon bouncing off the Lexan panels in the machine guarding.

According to efforts underway right now, it won't be long—a couple of years at most—before this scenario depicts how most shops will be running their machine tools. NC part programs as we've known them for almost 50 years will become passe. All that the machine tool controller will need is the digital product model represented by the 3D image on the Web page.

The CNC won't use G-codes. Everything it has to know about how to move the cutting tool is in the product model's database. There will be no need for creating a new and separate file of tool path data. Tool paths will be figured out in the CNC itself, based on the product model. That means there's no need for post processors either. Data will be formatted for execution by the machine within the CNC. And because the product model won't change, it will be available for machining "hard copies" whenever and wherever needed.

"Whenever" means as long as the product's life cycle is on-going. Twenty-five years is a typical life span for aerospace parts, for example. Neither changes in computer technology nor advances in machine tool technology over the years would affect the usability of the product model as machine tool input.

"Wherever" means anywhere an adequately equipped shop has authorized access to the product model database. With the Internet, that access is worldwide. Parts could be machined anywhere in the world through a global supply chain, with the digital product model serving as the universal "NC part program."

What will it take to make this dream come true? How much more has to be done to get there? How close are we right now?

The First STEP

The biggest step in this direction has already been taken. It's STEP, the STandard for the Exchange of Product model data, a comprehensive ISO standard (ISO 10303) that describes how to represent and exchange digital product information. STEP replaces IGES as the means by which graphical information is shared among unlike computer systems around the world. The big difference is that STEP is designed so that virtually all essential information about a product, not just CAD files, can be passed back and forth among users.

3D Model data is not used in manufacturing because even as simple supply chain must rely on too many interface among unlike computer systems. Suppliers 1 to 4 are subcontractors and job shops. Suppliers A to D are software solution suppliers serving various applications.

The core of the standard is a library of engineering definitions that can be assembled into various "application protocols" customized for the product models needed by particular industries and activities. A common library covers geometry, topology, tolerances, relationships, attributes, assemblies, configuration and other characteristics. New product models can be added as the need arises.

An extension to STEP has been created to cover product information related to CNC machining. This is STEP NC. STEP NC forms the basis for the scenario that caught your attention at the beginning of this article. The development effort to make STEP NC product model data usable as direct machine tool input has already progressed substantially.

In May 2000, a prototype for the sets of data required to add machining information to the product model of a test part was demonstrated. A later phase of this project will develop the machine tool controller capable of accepting this "super model" as input. The current test part is a milled workpiece. Turning and grinding are on the horizon. The "super model" demonstrated in May used an emerging Internet language called XML to add information about machining strategy, tool path planning, and tool selection. XML makes the resulting database "Internet ready'—a key requirement for global e-manufacturing.

STEP Vs. IGES

To understand STEP NC and where it's headed, a look at STEP and its relationship to IGES is the place to begin. IGES was about exchanging data and only the data contained in graphics files. STEP is about sharing data, allowing parties to work together by communicating information interactively.

IGES had its start 20 years ago when designers and engineers were turning to computers to create product designs. Instead of drawing lines and segment of circles on paper to make graphic representations of what a product should look like, they started making those lines and arcs on a computer screen. The completed design could be saved as a digital file. Although creating the original design file might take longer than preparing the engineering drawing on paper, the design file could be quickly copied, modified, printed and otherwise manipulated. These time savings more than made up for the extra time it took to prepare. Moreover, the digital nature of the design file allowed it to contain much more information in a much more flexible format.

STEP allows a single database of 3D product information to be accessed by several users regardless of the different computer platforms involved. Where several companies may be producing different parts for a complex assembly with critical tolerances, having a single shared database greatly simplifies product data managment and ensures that mating parts and subassembies can be manufactured effectively.

One big problem quickly emerged. The computer-aided design (CAD) systems used to create these digital design files were not compatible with each other. A design created on a Computervision system was meaningless to an Applicon system, for example. Companies with unlike CAD systems could not exchange CAD data.

The effort to resolve this situation got underway in the spring of 1980. Representatives of U.S. user groups, vendors and standards organizations began meeting regularly to create a neutral, non-proprietary database structure and data format for CAD files, dubbed the Initial Graphics Exchange Specification (IGES). In theory, CAD files translated into IGES could be exchanged with any CAD system that could translate IGES files into its own proprietary format.

Although IGES eventually became a workable, if imperfect, approach to exchanging CAD files, a major shortcoming with this approach became apparent right away. IGES allowed one system to communicate the lines and symbols of a computerized engineering drawing, but IGES failed to communicate the meaning of the information the drawing was intended to convey. It did not provide a reliable means by which product features could be transmitted with the geometry so that computer-based applications could "understand" the engineering drawing.

While IGES was being developed and gradually made more functional as it moved through the standards formation process, efforts to develop a true "product data exchange specification" were launched. The goal of this effort was to capture and convey "logical" information about product features and provide "physical" mechanisms for data exchange. Originally conceived as a U.S. initiative, this effort was soon seen as requiring international participation.

By 1984, this international effort to develop a Product Data Exchange Specification had been established under the auspices of ISO, the international standards making body. The goal was to define the methods for creating product data models that could be interpreted by computers. These models were intended to allow the exchange and sharing of product data in a way that the meaning of the data would not change throughout the product life cycle.

The international standards covering these product data models became known as STEP. For the last 15 years, various groups and committees (mostly comprising users rather than vendors) have been meeting regularly to develop standards for product data models. They have made considerable progress. Because the STEP standards are now sufficiently developed to cover all of the original purposes of IGES, IGES will receive no further development and refinement. STEP has officially taken its place.

By July 2000, every major and almost all minor CAD system vendors had STEP translators in the latest releases of their CAD products. Moreover, these translators have been tested for conformance and interoperability. With only a few exceptions did any of the translators fail to operate effectively. (Indeed, one of the innovative features of the STEP formation process was the early commitment to include testing procedures for assuring that STEP-compliant systems would truly function as intended. This provision may have slowed development but it appears to have paid off in the end.) In short, STEP is working. According to industry analysts, more than one million STEP enabled CAD stations are in place around the world.

Super Model Steps Out Quickly

Although standards-making activities are notoriously protracted, the Super Model project has maintained an intense pace from the outset, surprising and pleasing members of the Industrial Review Board who attended a review board meeting in May.

Says IRB member Gary Hargreaves, director of sales at CNC Software, Inc., "It is amazing to see the progress of the STEP Super Model project . . . going from a vision and discussions in December 1999 to something real, as shown during the May 2000 Industrial Review Board meeting just five months later. I now have tangible notes and information on how STEP NC technology can actually be implemented and supported for future CAM applications."

Another member, Bob Bean, president and CEO, CADKEY Corporation, had these comments after the meeting: "It is clear that with over 30 MCAD products available in the market today (and more start-ups entering the market every day), CAD data sharing and interoperability is a major challenge both in the short term and over the long term. When one looks at the stages of product and machine design such as conceptual, initial design, analysis, outsourcing of manufacturing, changes due to manufacturability, mold design, tooling, and so on, it is apparent that 3D solid model information needs to be leveraged throughout the design cycle. The STEP Super Model project is designed to facilitate not only the early phase of product development, but the full process to production."

Manfred "Whitey" Simon, a 30-year veteran of General Motors Advanced Manufacturing Engineering group was likewise encouraged: "The progress shown here is definitely in line with the scope of what is to be accomplished in a three year period. There seems to be lots of attention given to the real user interface—which is so important."

The IRB meets again in November 2000 at STEP Tools' headquarters in Troy, New York.

STEP NC

Although STEP NC has not quite completed the formal standards making process, it is well into the review and approval cycle, which will ultimately settle a few remaining matters of technical detail. STEP NC defines data representing "working steps," that is, a library of specific operations that might be performed on a CNC machine tool. In keeping with the STEP concept, these working steps are generic descriptions that can be incorporated into a product model. These descriptions are not linked to a specific format or code. However, STEP NC working steps are roughly equivalent to the machining commands represented by traditional M and G codes.

STEP NC is the basis, the enabling standard that underlies the potential for using the digital product model as machine tool input. STEP NC allows a complete database of machining information to be built around it. The database, then, dictates what capabilities must exist in the machine tool controller to cut the part.

What's called for is a "super model" that includes design information such as geometry, manufacturing planning information such as form features (holes, slots, contours and so on), plus manufacturing strategy information such as tool selection, fixture location and so on.

The effort to develop the super model and make it usable as machine tool input is being spearheaded by STEP Tools, Inc. of Troy, New York. STEP Tools is a developer of data exchange software for worldwide manufacturing. Although the official name of the project is the Model Driven Intelligent Control of Manufacturing, participants are simply calling it the Super Model project. Funding is coming from the National Institute of Standards and Technology (NIST), an agency of the U.S. Commerce Department's Technology Administration. The Super Model program was formally launched as an Advanced Technology Project with an award of $2.9 million in October 1999. Participating in the program is an Industrial Review Board consisting of manufacturers, software vendors and machine control builders, government and defense agencies, and a range of small- and medium-sized job shops from the Hudson Valley in New York State.

The Super Model project has a three year time line. The target for the first year is to build a STEP and STEP NC database containing three kinds of manufacturing features, and use the database to drive a machine tool controller. The target for the second year is to build a database containing all of the features defined by the STEP NC milling schema and use that database to manufacture the STEP NC test part. The target for the third year is to produce a database for another machining process such as turning, grinding or electrical discharge machining.

Dr. Martin Hardwick heads up STEP Tools, Inc., the Troy, New York-based software development company leading the Super Model project.

The Super Model Database
The challenge for the Super Model project is to create interfaces that bring together the information defined by STEP and STEP NC. Product geometry can be defined by one STEP application protocol. Product features can be defined by another STEP protocol. Machining operations can be defined by STEP NC. However, all three types of data and others must be integrated in a complete product model database. Moreover, this database must be Internet compatible.

Starting with product geometry in the STEP format is the easy part because STEP translators are built into most CAD systems these days (and they handle 3D geometry, doing so more effectively than IGES ever did, apparently). The super model test part happened to be created in a ProEngineering workstation.

The next step in building the database is adding features to the geometry. For the sake of demonstration, STEP Tools originally used a Microsoft Excel spreadsheet to link STEP-defined feature names to the test part geometry. The Super Model program is evaluating an automatic feature recognition system being developed by Honeywell FM & T, one of the subcontractors in the program. Called the FBMach Process Planning System (FBMach is short for feature-based machining), this software reads STEP geometry and automatically determines what features, such as holes, pockets, slots, and so on, are represented by the geometry. The user interface allows these determinations to be validated before proceeding. The FBMach system is expected to be available commercially by the end of 2000. Its application to the super model test part will be demonstrated in November.

STEP NC establishes a hierarchy of workingstep supertypes/subtypes. In other words, it breaks down every machining operation into the steps required to perform the operation. These steps include actions to be taken as well as data (such coordinates of point-to-point motion) to be applied. These steps are then linked to the appropriate part model geometry to fill in the values. STEP Tools is setting up tables to match workingsteps, workingstep-methods, workingstep actions, and machined features.

According to Martin Hardwick, president of STEP Tools, the super model database is adapting a modified version of the company's ST Repository product data management software to structure the database. Each repository uses standard interfaces to import and export geometry, features and workingsteps to the tools used by CAD and CAM engineers.

A key part of STEP Tools approach to the super model database is the use of XML in its interfaces. XML, the eXtensible Markup Language, is a vendor-neutral data exchange language for passing information, not just data, across the Internet. XML allows data to be "tagged" so that software applications reading the database can identify what type of information is stored in the database and extract the data that is needed. HTML, the Hyper Text Markup Language, is a similar"metadata" language that the Web uses so that text can be displayed no matter what Internet browser happens to read it. XML offers a comparable level of interoperability. An XML standard for STEP is nearing completion. This standard will ensure that all data in a product model is "tagged" in the same way.

For the super model, XML provides a convenient means to link manufacturing strategy, tool pathing, and tool selection information to geometry, features and machining steps in the database. By sorting out data with the appropriate tags, for example, geometry identified as a hole to be drilled can be linked to operations such as rough drilling, boring and counterboring steps. Each of these steps will require that other data be extracted, such as workpiece material, surface finish requirements, and so on, to link with speed and feed tables. XML provides the tags so that the data is sorted correctly.

Ultimately, XML ensures that a CNC networked to the Internet will be able to find the information it needs from the product model database to machine a part.

At the May 2000 Industrial Review Board meeting, STEP Tools demonstrated how XML transactions had been used to complete a database for its test part, linking the required information for three different types of machined features, including a hole, a slot and a pocket.

Down To The CNC

The goal for the Super Model project is to show how these features can be cut on a machining center using the product model as the NC part program, so to speak. One of the subcontractors deeply involved is this phase of the program is Electro-Mechanical Integrators, Inc. (EMI) of Franconia, Pennsylvania. Engineers at EMI are writing new software for a Bridgeport control unit that will enable it to accept STEP NC data. (The company has considerable experience with Bridgeport control units and is the factory-authorized support and repair agency for the Bridgeport DX32 control.)

A Bridgeport V3XT milling machine like this one is being outfitted with a CNC customized with special software. This software will enable it to interpet the super model database and use the information to machine the part without a conventional G-code program.

According to Bart Stater, head programmer of EMI, this effort requires a customized command parser and command interpolator to process STEP NC. "Essentially we are creating a new CNC protocol to interpret the information in the product model in real time. This software will extract the data it needs to determine axis moves, get the specified tool, and issue commands. It will not need or use G-codes," he says. Otherwise, the I/O structure and servo system of the machine remain the same. He notes that this concept assumes that the CNC will be networked to a file server that receives and stores data, most likely through an Internet connection.

EMI is looking at two approaches to configuration of the CNC. One approach runs all of the executive software in the CNC's internal processors. Another approach uses a "PC front end" interfaced to the CNC. The PC would process the STEP NC data and spoon feed it to the CNC, filling a buffer with blocks of data on demand. This approach would ensure that the CNC is not starved for data while the product model is processed.

In November 2000, EMI is scheduled to demonstrate actual cutting of the three selected workpiece features on the test part. Although the concept could be proven with a simulation of the machining operations, cutting chips is a more convincing demonstration. "We want to show the CNC accessing the product database on the Web, finding the features to be machined, then generating commands to drill the hole, mill the slot and machine the pocket," Mr. Stater insists.

STEP Tools is also working with the Lawrence Livermore National Laboratories, where a STEP NC interface is being developed for the OMAC (Open Modular Architecture Control) project. Additional shopfloor tests and demonstrations of STEP NC are set to take place at a production machining facility operated by General Dynamics Land Systems in Scranton, Pennsylvania. A pilot project at the Jet Propulsion Laboratory is also in the proposal phase awaiting funds.

Art To Part

Those three words sum up the promise of STEP NC and the Super Model project.

From a shop floor viewpoint, art to part means the intermediate steps of creating an NC program are eliminated. Most of those intermediate steps necessitated a transformation of product data, causing data files to proliferate. Part geometry had to be translated, reconstructed or edited. The edited, translated or reconstructed geometry had to be processed to generate tool paths. Tool path files had to be post processed to suit the requirements of the machine tool and control unit combination. Postprocessed files were often edited on the shop floor. In short, one piece of part geometry begot hundreds by the time the part was actually cut from metal.

With STEP and STEP NC, the digital product model database replaces all of the other product data files otherwise created to make the part.

From a design and engineering viewpoint, art to part means that design and manufacturing can be managed with a single database. Just as data files need not proliferate down the supply chain, they need not proliferate across the manufacturing organization. Product data can be shared between products, between corporate divisions and between applications. The Internet will make this sharing of data global and virtually instantaneous.

This concept of art to part does make G-code programming obsolete. But this traditional form of programming for machine tools was already on its way out. Advances in CAM software make G-codes less and less visible to programmers and machine operators.

This concept also implies that CAD and CAM will have a different relationship than they did in the past. Dr. Hardwick believes that product models will originate in CAD, with STEP enabling a high degree of collaboration between designers and engineers. Feature recognition will be applied at this level as manufacturing engineers define the manufacturing process that becomes part of the product model. "At this point, the process data will be ready for any machine tool but will allow for important local parameters to be defined when it gets to the machine," he predicts. Selecting cutting tool, setting feeds and speeds and so on will be handled at the machine tool on the shop floor.

The super model solution seeks to replace hundreds of product data managment files with one database from which data may be shared via the Internet. The translators, editors, converters and postprocessors require to exchange or reformate product files are unnecessary.

These CAM functions become the domain of intelligent controllers with on-board CAM software. This software will generate the movements necessary to make the parts after the appropriate parameters have been set on the CNC. "The on-board CAM software is there to do the last minute custom tool path generation using selections made by the operator," Dr. Hardwick says. Intelligence built into the software stops the operator from making mistakes or using less than optimum settings. "It's a huge opportunity for the CAM industry. This software will be a required component of all future CNCs," Dr. Hardwick contends.

Vision

With the development of STEP NC, what's happening is not simply the re-shaping of CNC. It is the reshaping of manufacturing. And in the vision that is emerging, the CNC machine tool will be more important than ever.

STEP - Internet Links

STEP-NC
www.steptools.com/library/stepnc
STEP-NC is a worldwide effort to extend STEP to define data for NC machines. These pages include an overview of the project, and the specification.
Interoperability Success Stories: STEP
http://www.mel.nist.gov/msid/sima/daratech
Boeing Commercial Aircraft, Boeing CSTAR, Delphi Automotive Systems, Lockheed Martin
STEP Glossary of Terms and Acronyms For The Technical at Heart
http://pdesinc.aticorp.org/Glossary.htm
This link provides definitions for commonly used terms in the context of STEP.
PDES, Inc.
http://pdesinc.scra.org
An International industry/government consortium accelerating the development and implementation of STEP. Worldwide news of STEP including press releases and announcements
Lockheed Martin Releases News on STEP implementation
http://www.mel.nist.gov/msid/98whatsn/3-4-98.htm
As part of its ongoing effort to foster product affordability, Lockheed Martin Tactical Aircraft Systems (LMTAS), in Fort Worth, Texas, recently implemented an international data exchange standard known as the Standard for the Exchange of Product Model Data, or STEP, on its F-16, F-22, Joint Strike Fighter, F-2 and KTX-2 programs.
Automotive Interoperability Cost Study
http://www.mel.nist.gov/div826/msid/sima/99ovwvis
What is the economic cost due to lack of interoperability in the automotive supply chain? Conservatively, One Billion Dollars Per Year! Conducted with NIST Strategic Planning and Economic Assessment office in March 1999. This slide presentation is easy to use and study.
Publication: STEP the Grand Experience
http://www.mel.nist.gov/msid/99whatsn/10-1-99.htm
The Manufacturing Engineering Laboratory of the National Institute of Standards and Technology is proud to announce its book publication, "STEP the Grand Experience."
Fundamentals of STEP Implementation [PDF]
http://www.steptools.com
This white paper walks you through a the initial stages of a typical STEP implementation project. You will need an Adobe Acrobat viewer to read this.
STEP - Information Sources
http://www.nist.gov/srd/astm/astm-ym/tsld016.htm
http://www.tc184-sc4.org
SOLIS a repository of STEP working material on the Web.
Investigating the STEP Data Standard at No Cost
http://www.steptools.com/translate
For those who are interested in exploring the STEP Data standard, STEP Tools, Inc. offers a free Online Data Translation Service. CAD users wanting to convert 3D data to and from STEP part files will find a variety of translation options, including popular graphic data formats. To date, over 8000 data translations have been performed online.
European STEP-NC Project
http://www.step-nc.org/
This site is the hub for the European Perspective of STEP.

Steel Strikes Back

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 14:15:00 +0000

One of the things that the steel industry has done over the past several years is to aggressively position itself vis-à-vis competitive materials. Not only is this being done on a company-by-company basis, as new materials are developed, but also through coordinated efforts, specifically those of the Automotive Applications Committee of the American Iron and Steel Institute (www.autosteel.org). The objective is not to simply react to what other material suppliers are doing, but to take a proactive approach in proving to vehicle and component manufacturers that, although the proffered approach is different materials for different applications, chances are the material they’re most interested in seeing being deployed happens to be ferrous. And more specifically, of the steel variety, as opposed to iron.

When you’re building an engine that produces 505-hp, like the Corvette Z06 LS7, what would you use for the crankshaft other than forged steel?

Consider Cranks. Consider, for example, that the move toward cast iron crankshafts starting in the 1970s raised some considerable concern because the material that was losing out in this switch happened to be steel. Yet as Dave Anderson, director, Bar and Rod Programs, AISI, points out, GM’s Buick Div., which is looking for performance and improved NVH for its vehicles, is using engines fitted with forged steel crankshafts under the hoods of its latest vehicles, the Lucerne and the LaCrosse. Specifically, the 275-hp 4.6-liter Northstar V8 in the Lucerne and the 255-hp, 3.6-liter V6 in the LaCrosse both have forged steel crankshafts. Because of the rigidity of these cranks, there’s little vibration, which helps Buick achieve the sort of “QuietTuning” that it is seeking. In addition to which, there is the performance aspect of the steel cranks, too. So a great example here is found under the hoods of two Cadillac performance models, the STS-V and the XLR-V, both how which have the 4.4-liter supercharged Northstar V8, which produces 443-hp for the XLR-V and 469-hp for the STS-V.

And as an example where the steel crankshaft really performs is under the hood of the Z06 Corvette, which uses the 7-liter, 505-hp LS7 hand-built V8 engine. 4140 steel is used.

Anderson points out that if diesel engines grow in popularity for light vehicles, then the number of forged steel crankshafts will grow accordingly, as the higher compression ratios of that type of engine necessitates the use of steel cranks.

Although the Pontiac Solstice is a low-volume vehicle and even though it has some seriously formed body panels, it isn’t made of plastic. It’s steel. The panels are made with a sheet hydroforming process. The hydroforming not only allows the steel panels to achieve shapes that one ordinarily doesn’t associate with steel (e.g., look at the clamshell hood), but it has lower tooling costs than is the norm when it comes to producing steel parts. Shown here is the ’07 GXP model.

Strength & Durability. Another material that steel is staring down under the hood is powdered metal, which, Anderson admits, has the larger proportion of connecting rod applications under the hoods of cars built in the U.S. However, he points out that the preponderance of engines built for European and Asian applications have forged steel con rods, primarily because, Anderson says, “forged components are stronger and more durable.” Those engines tend to operate at comparatively higher rpms, which puts stress on the con rods, which means that strength and durability are paramount. While he acknowledges that there may be a weight advantage to using powdered metal, “If the con rods are redesigned”—for forged steel—“then they can be lower in weight than powdered metal.” He also explains that while there is also a cost advantage for powdered metal, “the cost differences are coming down because of near-net shape forging.” The use of a material like C-70, which is a crackable steel (which allows the cap to be separated from the rod without requiring machining of the mating surfaces for subsequent reattachment) has been shown to allow weight and manufacturing cost reductions for connecting rods. (It should be noted that the aforementioned LS7 engine doesn’t use steel for its connecting rods—they’re forged titanium.)

Trapping Emissions. Another area where steel has lost significant ground that it is working to recover is in the production of fuel tanks. Here the alternative material is plastic, which is light and easily formable. So the AISI organized the Strategic Alliance for Steel Fuel Tanks (SASFT) initiative, which examined the ways and means to regain some of what has been lost to blow-molded products. One of the concerns with steel has been that of corrosion. So SASFT undertook a two-year corrosion test program to assess both internal and external corrosion potential. According to the results of the study, the steel tanks are good for “up to 20 years,” which means that they meet the California Air Resource Board (CARB) 15-year durability requirement. Chuck Potter, AISI senior automotive consultant, also points out that when it comes to evaporative emissions—a key concern for vehicle manufacturers that are looking to meet CARB’s Partial Zero Emission Vehicle (PZEV) requirements—a single layer of steel can get the job done versus multiple layers of plastic. And while on the environmental front, there is another issue related to gas tanks: What happens at the end of life? Potter says, “Steel is 100% recyclable. Plastic tanks get thrown into land fills.” Certainly that is a consideration for the environmentally minded.

Steel Steps On Aluminum

The original aluminum pedal set for the Lotus Elise and Exige may have a high-tech look, but the new lightweight steel pedal box (inset) swaps cables for drive-by-wire electronics, has better pedal feel, and needs less space.
(Photos courtesy of General Motors)

In a move sure to confound many, Lotus Cars has switched from extruded aluminum pedals in its Elise and Exige models to a hybrid system that uses solid steel pedal arms and extruded aluminum pads. Unlike the previous latticework design, the new lightweight pedal box has an integral mounting point for the drive-by-wire throttle electronics. In addition, Lotus took the opportunity to reduce the brake pedal ratio, improve the feel of the throttle and brake, and reposition the pedals for easier “heel-and-toe” downshifts. These items, Lotus engineers say, would have been more costly and difficult to do with the aluminum pedal arms due to their comparative lack of stiffness.

Although plastic had previously had advantages as regards to both weight and formability for fuel tanks, Potter says that advanced high-strength steels are competitive on both counts.

Another application that steel once had 100% of the market for is wheels. Now steel accounts for less than 50%, with aluminum being the material of choice when it comes to styled wheels. Steel hasn’t disappeared, but has been pretty much relegated to the low trim levels for vehicles. However, what some wheel manufacturers are doing is using steel for creating a base and then adding trim (including plastic), plating, or painting, thereby producing comparatively lower-cost wheels with a higher-cost appearance. Applications of these wheels range from the Ford F-150 to the Lincoln Navigator.

Body Building. So far as the body-in-white goes, steel is strong. Yes, Potter and Anderson both admit that vehicle manufacturers are always looking at alternatives like aluminum and composites, but that steel continues to hold the advantage. Not wanting to lose and then regain as steel has in the aforementioned applications, the steel industry is working hard at creating new materials—Anderson says, with tongue perhaps only partially in cheek, “Steel is old and has been around for a long time. We’re looking to change its name—ferro-alloy.” Something that sounds sexier. But from the technical point of view, the materials that are being promulgated by the industry are advanced high strength steels (AHSS). These are materials with a yield strength greater than 550 MPa. Included in this are materials with improved formability—dual phase and transformation induced plasticity (TRIP) steels—and those with increased tensile strength, crush resistance, and energy absorption—complex phase and martenstic steels. One of the advantages that Potter cites for steel versus, say, aluminum, is that there is a greater familiarity in the auto industry as regards steel, especially when it comes to manufacturing with the material. He admits that the higher mechanical properties and the microstructures of the AHSS materials are different than what has historically been the norm means there must be some adjustments and precautions when it is used in place of the traditional HSS materials, “it doesn’t take wholesale manufacturing equipment changes.” Upgrades to dies (springback is greater for the AHSS materials) and different welding parameters are likely to be necessary, but those are comparatively minor.

One vehicle that makes the steel people exceedingly happy is the Pontiac Solstice. Although the vehicle “borrows” the hydroformed frame rails from the Corvette (i.e., it has the same underlying architecture as the ‘Vette, not the same rails), it doesn’t borrow the plastic body panels. It has a steel body—even though one might think that with clam shell hood plastic would be a natural. (Sheet hydroforming is used instead of plastic molding.) “Plastic used to assume the low-volume advantage,” Potter says. “It’s interesting that we can now say that there’s a low-volume scenario with steel.” The Solstice and platform partner Saturn Sky are going to account for about 20,000 units per year (a number which is likely to go up with demand).

Plastics: The Return of Body Panels?

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 14:10:00 +0000

Although there might be some people who think that in the light of the fact of the relative lack of success of the SMART vehicle lineup and the fact that the company that made plastic cars comparatively cool, Saturn, is moving toward steel with alacrity, don’t count plastics out for body applications, not by a long shot. In fact, according to Derek Buckmaster, global market director, Exterior Body Panels & Glazing, GE Plastics (www.geplastics.com; Bergen op Zoom, The Netherlands), new materials developments are showing solutions vis-à-vis one of the key problems that plastics seem to present, which is the coefficient of thermal expansion (CTE). Buckmaster explains that the problem is a simple one. That is, most body structures are steel. Steel has a CTE of around 1.9. Most plastics, on the other hand, he says, have a CTE between 5 and 10. “If you’ve got plastic exterior panels and it is a hot day, the gaps may no longer exist, and that’s not a good thing,” he says with understatement. “That has been known to happen. I know of an OEM in Japan that built a prototype vehicle with plastic doors, and they literally couldn’t get in on hot days.”

Although otherwise a study in aluminum the BMW 6 Series features plastic fenders in order to achieve the design intent.

So the issue is one of lowering the CTE for plastics. And Buckmaster says that they’re working on two different materials for body panels that have reduced CTE. One of them is what they’re calling “HMD” or “high modulus ductile.” He explains, “Say you have a polycarbonate—one of the best materials in terms of impact resistance, or ductility—and you want it to be stiffer. You would typically put glass fibers in it. But the glass fibers cause it to become brittle. So you always have this trade-off between a stiff material and an impact resistant material.” Enter HMD technology. Rather than adding glass, they are adding a nano material. He says that exactly what the material is is proprietary, but he does admit that it is not a nano-clay, which has been used in some automotive applications (e.g., the 2002 GMC Safari and Chevy Astro vans had a running board with a nano-talc material included in the TPO base; see: http://www.autofieldguide.com/columns/1001mat.html). This material, Buckmaster says, “sets up a secondary structure within the plastic itself and builds a nano-scale skeleton that stiffens the material without losing the impact resistance. It is very different to how you would use glass fibers to stiffen a polymer matrix.” Depending on the resin used, Buckmaster advises that the CTE can be reduced by as much as 50%.

This development is moving toward production, he says. “We’re launching a PCPBT [polycarbonate polybutylene terephthalate] material, Xenoy, with the HMD technology. We’ve already done trials with Krauss-Maffei”—a machine manufacturer—“and BMW and have seen some terrific results. There are a couple of car manufacturers looking at it.” He predicts that within the next 24 months there will be parts produced with the HMD technology. “It’s precisely about reducing the gaps and improving the coefficient of thermal expansion on the vehicle.”

While the HMD technology is for injection molded parts and is suitable for components including door skins and fenders, there is another material technology that lends itself to the production of horizontal panels including hoods and roofs. This is a “high performance thermoplastic composite,” of “HPPC.” Ordinarily, composite materials are glass or carbon fibers in a matrix of a thermoset, an epoxy or a polyester material. The materials are combined, then put in an autoclave, where they are subjected to high temperatures and high pressures. While the part produced tends to have excellent engineering properties, as a practical manner, the cycle times are such that production part applications are exceedingly limited. However, according to Buckmaster, because the HPPC uses a thermoplastic base rather than a thermoset, with continuous glass fibers as the stiffening material, part production is expedited because what’s involved is melting the thermoplastic, molding, and cooling it down again. The cycle time is much shorter than is the case with conventional composites. “Because HPPC is glass-filled and the fibers are continuous, you don’t get that sagging you used to get in the past,” Buckmaster says, referring to the fact that historically large horizontal plastic panels have either been avoided or ribbed on the underside because of this tendency to sag. “We tend to have the same stiffness as a piece of aluminum sheet.”

With a vehicle as tough as the H3 one would think that the body would have ferrous materials abounding. But the deep drawn fender forms necessitated the use of plastic.

Buckmaster suggests that within the next year there will be production parts produced with HPPC. But does this mean that there could actually be a return to plastic skins on cars? Probably not on a wholesale basis. Buckmaster admits that one of the issues that they’re faced with when dealing with OEMs is that of an installed base of metal stamping machines: How can plastic parts production be justified if the machinery sits idle?

Perhaps part of the answer to that question simply goes to the design advantages that Buckmaster says plastics can provide. He explains that typically, if OEM designers want to save weight they consider aluminum, but then pay a cost penalty. What’s more, he says, “Typically, because aluminum’s ductility is not as good as steel, they’re limited in the depth of draw that they can pull on a sheet metal pressing. So that means you have to go to more expensive tooling and be gentler on the aluminum sheet or”—and here’s where the other shoe drops, as you might expect—“you can move to a polymer material.” He provides a solid example of a case where aluminum is used—but so is plastic for the fundamental formability: The BMW 6 Series. “Look at the body-in-white of that vehicle,” he says. Although the majority of body panels are aluminum, the front fenders of the vehicle are made of Noryl GTX. “They would have done it with aluminum if they could have,” Buckmaster claims, “but with the styling design—the curvature and the depth of draw—it wouldn’t be possible.” (The decklid is an SMC composite.)

Another example that he cites regarding the importance of formability is one that is probably more unexpected than that of a sleek coupe: The fenders on the 2006 HUMMER H3. “They’re a complex, deep-drawn shape that are not possible to make with steel or aluminum,” Buckmaster suggests. The fenders, produced with Noryl GTX resin, are said to be the first thermoplastic fenders on a North American truck platform.

STEEL Improves C-Class Structure

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 14:08:00 +0000

When it came time to reengineer the most popular model in the Mercedes-Benz lineup, engineers focused on making the body-in-white stronger, safer, yet lighter. These seeming contradictions (i.e., don’t stronger and safer mean heavier?) forced the team to reevaluate its material choices to meet this challenge, and resulted in a surprising outcome: Approximately 70% of all the steel panels on the body shell of the 2008 C-Class use high-strength steel alloys; a rate Mercedes says is unprecedented for a passenger car. Engineers also used ultra high-strength steel in 20% of the body shell to enhance durability and safety. Together, their expanded use provides unexpected weight savings and improved body rigidity. “We have managed to put an end to the weight spiral,” said Thomas Weber, head of Mercedes research and development. “In the body shell alone, intelligent use of high-strength steels has produced a weight savings of 17.6 pounds.” Torsional resistance also improved by 13% when compared to the outgoing model.

The 2008 Mercedes-Benz C-Class uses ultra- and high-strength steels to provide a structure that is lighter, stiffer and safer than the previous model.

Svelte Safety
Beyond the weight and stiffness benefits, Mercedes also touts the safety benefits of using ultra- and high-strength alloys. Development engineers were able to enlarge the crumple zones through the use of the materials, resulting in improved energy flow and occupant protection. The structure on which the engine, steering, front axle and transmission are mounted, is constructed from high-strength steel and is extended forward, forming an additional impact plane at the lower section of the vehicle, allowing it to act as part of the front deformation zone. The use of high-strength steel also improved deformation and energy absorption characteristics. Ultra high-strength steels and panels of varied thickness are used in the construction of the occupant cell. The main floor structure is comprised of three steel sheets laser-welded together with the thickest sections forming the center tunnel backbone. Continuous floor side members, constructed from steel with reinforced inner sections, provide added protection. Hot-formed, ultra high-strength steel in portions of the B-pillars absorbs large forces and transfers them to the main body side structure in a side impact. The pillars are made up of three formed steel layers with a large, reinforced area that extends to the upper belt deflector point. High-strength steel plates with reinforcements are placed in the frame, waistline and bumper levels of the door. At the rear, the side members are comprised of continuous, closed box sections with defined material thickness at various points that enables the structure to absorb large energy forces. An ultra high-strength bolt-on steel cross member is manufactured via a flexible rolling process that allows the thickness to vary—the outer edge thickness is greater than the inner section—for better impact load management. As a final touch, Mercedes engineers made the steering rack from high-strength steel, which cut 1.7 lb from the steering system.

Plenty of automotive engineers are taking advantages of the comparatively new steels. The 2008 Mitsubishi Lancer utilizes high- and ultra-high-strength steel in its body-in-white, improving torsional rigidity by 56% and bending rigidity by 50% over the previous model. Engineers use the ultra-high-strength 980 MPa alloy for constructing the rocker panel between the A- and C-pillars, resulting in improved side-crash performance. High-strength 590 MPa alloy makes up the B-pillar, roof joints and cross-car structure, adding to the safety credentials.

All Machine Tools Are Not Created Equal

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:55:00 +0000

There are almost as many machine tools as there are potential and actual users combined. Each builder has its own niche (or niches) and adds its own "flair" to the machine, making it that much different from the competition. To try and name every builder and every machine here would be impossible, yet a valiant attempt will be made to break everything down and let you know what to expect from a range of machine tools, from verticals to horizontals to universals.

Trend: Controls

While every builder goes to great lengths to make its machines unique, there are a couple of things happening out there that can be labeled "trends." The first of which is the evolution of controls from tape reader to full-out PC. Most, if not all, machine tool makers feature controls that are dubbed "PC-based" or "PC-compatible." A recent survey of those involved in control technology see industrial PCs completely overtaking the control market in the next few years. In fact, many companies have already begun creating "open architecture" controls, meaning that the user can configure the controls to exactly their specifications. Others have gone one step further, putting all capabilities into software, so that nearly any hardware will do, because the control is actually the software. Either way, users had better be pretty computer savvy, and had better be prepared to become more so.

Another trend seeping into the realm of controls is Windows NT. Most hardware and software providers are banking on the fact that Bill Gates will take over the machine control market also, and are converting to a Windows NT environment. Short of this, they may offer Windows NT as an option, and let you decide.

Combining these two technology directions leads to an exciting possibility for the future: networkability. While many controls are plugged into user local area networks (LANs), few have yet to be reliably brought into the realm of the World Wide Web. Once the issues of reliability and security are cleared up, Tier 1 and Tier 2 suppliers will further tighten up the supply chain, transferring CAD/CAM data from the design department at one company directly to a machine at another.

Some Specifics

Out of all of the newer control technologies out right now, the slickest looking features are coming from combining mega-capable hardware with creative software solutions that help boost machine capabilities. For example, the BostoMatic BDC 3200X CNC from Boston Digital Corp. (Milford, MA) uses software algorithms, 32-bit VME bus architecture, and multiple microprocessors to enable the processing of 1,100 five-axis blocks per second. While achieving such high speeds is something else, the control gets slicker when you consider that no preprocessing is required, even on the most data-intensive part programs. Contour optimization software and user-programmable servo parameters round out the 3200X's features.

Creative Technology Corp.'s (Arlington Heights, IL) Creative Evolution is a PC-based control that Defiance Machine & Tool Co., Inc. (Maryland Heights, MO) counts on to give its small machining centers a few extra punches. A look-ahead feature scans for corners, and automatically adjusts speed and feedrate to prevent gouging and provide rounder corners. The system also provides automatic chamfering, canned milling and Z-axis cycles, mirror-image programming, and an on-screen text editor that includes global program modification.

Trends: Spindles

Used primarily to machine EDM electrodes, the Defiance VTX line of tabletop machining centers gets a lot of its precision and capability from its control and specially designed software from Creative Technologies.

There's something fishy going on with spindles. Everyone is talking about self-balancing, high-speed spindles, but no one we've found will talk specifically about them. Several machine tool companies are "looking into" the development of these units, but mum's the word until they're ready to launch the product. Of course, there are some self-balancing spindles out there already, but they are incredibly expensive, and are really still in the R&D stage of things. It should be interesting to see what develops in the next few months.

Some Specifics

The tilting head spindle configuration from Mandelli is designed to provide precise machining under tough conditions. This particular tilting head is used to machine various car components at Ferrari's plant in Maranello, Italy.

In the mean time, there are some tangible advances being made in regard to spindle technology. One that stands out is the tilting head configuration at Mandelli (Rockford, IL). While tilting head spindles add a fifth axis, they tend to be too delicate to stave off vibration and other accuracy inhibitors. Taking that into account, the company's engineers have developed a high-torque spindle that can handle heavy-duty cutting applications, but without sacrificing accuracy. Combining that with the standard Sinumerik 840D control from Siemens, this system can really cook through some mold and die applications.

Trends: Toolchangers

As with the rest of the machine, toolchangers have gotten more sophisticated. Some systems are capable of tool condition monitoring, reporting data back to the control; and many ATCs feature a load cell that monitors whether the tool is present, and transfers tool length data to the control as the tool is mounted to the spindle. Manufacturing cells and flexible systems now use one toolchanging system for several machines, saving space, time, and money. A robotic system patched into the machine's control moves tools from machine to machine as needed.

Some Specifics

Changeover times range from 10 seconds in cells and systems, to 1.5 seconds in some of the smaller horizontal machines. Capacity ranges from 12 tools to hundreds. Shank type depends on the spindle. A system from Mikron Corp. (Monroe, CT) uses rotary magazines with 12 positions each. This lets users set up tool sets for specific jobs, and switching from job to job only means lifting out one magazine and replacing it with another. The system is expandable up to 40 positions.

Trends: Feed & Speed Rates

With most vertical machines, the magic number seems to be 787 ipm rapid feeds in the Z-axis and around 1,100 ipm in the X and Y axes when you're talking vertical machining. Horizontals are capable of faster speeds, hitting around 1,100 to 1,400 ipm.

Some Specifics

Going fast isn't just a function of the spindle and the cutting tool anymore. Machine tool builders are using software to get things moving faster. Makino (Mason, OH), for example, has a software function called "rapid traverse bypass." It determines where the spindle needs to be, allowing rounded corners on rapid paths to get it there. Enshu U.S.A. Corp. (Elk Grove Village, IL) uses a programming algorithm to provide fast, synchronized tapping with forward control. According to Enshu, the algorithm works even for extremely small diameters.

Trends: Work Changing

To speed up automated pallet changeover, most companies are incorporating shuttle control into the programming of the machining system's control. Here again, the configuration of the changer is going to be up to the user.

Some Specifics

The Flexline manufacturing system from Chiron is packed with a lot of time and money saving features, but one of the more interesting ones is a part changing system that uses robotic arms to perform changeover in about 10-seconds.

Five-axis machining for under $200,000? Yep. The HS-1R 5AX horizontal from Haas Automation, Inc. (Oxnard, CA, seen here performing porting operations on a cylinder head, features X,Y, Z travels of 24 x 20 x 22 in., respectively, and a standard extended table measuring 15 x 40 in. All of the bells and whistles are integrated into this machine: full five-axis control, a 7,500-rpm spindle powered by a 15-hp motor, rapid traverse rates of up to 710 ipm, a 24-pocket toolchanger, and a chip auger that automatically senses loads to prevent jamming.

One of the more unique (and quick) workpiece changeover systems comes from Chiron America, Inc. (Charlotte, NC). Its flexible transfer lines employ a rail-guided robot moving from station to station, and back to a load/unload station. Moving at 8,000 ipm, the robot zips from machine to machine, and changes parts in around 10 seconds. An optional part magazine allows unattended operation for long periods of time.

Trends: Construction

Ribbed, cast iron, Meehanite, even concrete. The base material and construction of machining centers are both common and different. Not to say that machine tool builders have lost their creativity in this regard. Quite the contrary. Builders are left with the dubious task of making machines that have as large a work envelope as possible while maintaining rigidity, while damping vibration, while not taking up too much room. You get the picture.

Some Specifics

Looking again at Mikron Corp., its machines feature a cast structure in a portal design. Two portal supports are fixed on the base, and the transverse beam accommodates the cross slide. The Z-axis runs on top of this. According to the company, the symmetry of the design naturally minimizes vibration.

Clearly, the machine tool industry is extremely competitive, and builders work very hard to stay one innovation ahead of its competition. If they all stay on the track they're on, users will be machining parts in France from their living rooms in Ohio before we know it.

Things to Know About Cam Grinding

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:52:00 +0000

The changing shape and composition of camshafts are challenging those responsible for surface finishing. As a result, an increasing number of cam-grinding operations are being performed with cubic boron nitride (CBN) superabrasives and technologically advanced conventional abrasives.

Camshaft grinding requires instantaneous changes in wheel-work contact length and material removal rates. In camshaft grinding, the arc of the contact between the wheel and the camlobe changes continuously as the base circle, flanks and nose are ground (see illustration). The arc of contact can be represented by means of the equivalent diameter (De) and can be calculated:

*De =*	Ds x Dw
	Dw ± Ds

with:

Ds is the wheel diameter
Dw is the work diameter
+ is to be used when Ds > Dw
- is to be used when Ds < Dw

A large equivalent diameter represents a longer arc of contact between the wheel and work material. So the arc of contact is large as the wheel passes over the flanks and becomes smaller as the nose and base circle are ground.

As the De increases, more abrasive particles come in contact with the work material. This reduces the force acting on each grain, and makes the ploughing and sliding interactions more dominant. This is usually observed as increased grinding power or force for the same grinding condition.

In camshaft grinding, as the De is larger while grinding the flanks, higher power will result if the radial infeed and work speeds are maintained the same as when grinding the nose or base circle. This can result in unacceptable thermal damage on the lobes. In order to avoid this problem, the work speed is generally reduced as the wheel grinds the flank portions. This reduces the rate of material removal and helps lower the grinding power.

Take Care

The equivalent diameter in camlobe grinding.

Camlobe grinding is a complex variant of cylindrical grinding. When raw camshafts are manufactured—by casting in sand or shell molds (cast iron), forged or machined from barstock (steel)—roughly 0.02 to 0.12 in. of stock is generally available for grinding. After the lobes and journals are induction hardened, the journal bearings are ground, usually on a centerless or cylindrical grinder. Since the camshaft is supported on workrests, with the journals as a reference during camlobe grinding, it is important that the journals be ground properly because any imperfections will be translated to the camlobes during lobe grinding.

Although the necessary surface finish on the lobes and journals is usually provided by the grinding, they are often lapped with fine-grit abrasive belts. Lapping after grinding has been found to be effective in reducing initial friction during the engine break-in period.

New Profiles

During the past decade, camlobes with a re-entrant profile have been gaining popularity because this design helps increase engine torque and horsepower and reduces emissions. In re-entrant camlobes, the ramps are concave instead of a straight line; this helps in opening and closing the valves much faster.

Also, the use of roller bearings at the interface with the camshaft in place of flat tappets has reduced friction, permitting higher engine speeds. However, the sharp line contact results in significant increases in contact stresses, which can exceed 250,000 psi. These high stresses can result in spalling and accelerated camlobe wear. So depending on the magnitude of the contact stresses, camshafts of different construction are used.

For lower contact stress applications, induction hardened or chilled nodular cast iron may be acceptable.

For contact stresses of 250,000 psi and above, steel cams can provide the most-reliable solution.

Composite Approaches

Composite camshafts of medium- and high-alloyed powered metal lobes mounted on a hollow tube are popular as they have the capacity of withstanding high contact stresses and offer improved tribological properties. Composite camshafts can be 50% lighter than cast iron or steel shafts; can have lobe material tailored to the application; and they can have lobes molded to near-net shape, which means that the amount of grinding stock, and consequently grinding time, are both reduced.

The requirements to have high-strength, low friction and minimal wear have prompted Japanese researchers to consider ceramic camlobes.

Camlobes are usually machined to final shape by grinding with bonded abrasive wheels containing aluminum oxide or CBN. Usually, one lobe is ground at a time, although in order to improve productivity, machines using multiple abrasive wheels are available. With this equipment, two wheels are mounted on a one-piece precision-balanced hub to grind two lobes at a time. But this approach can be used only if the lobes being ground simultaneously have similar lift profiles.

Abrasive Belts

Another approach to improve cycle time is using machines with abrasive belts. This was developed in Italy in 1977; it was successfully implemented by GM engineers only in the early 1990s. In these machines, the abrasive belt is pressed against the workpiece by a cylindrical contact shoe that, together with the belt, replaces the curved surface of the grinding wheel. These multiple-belt cam grinding machines can grind all lobes simultaneously for cycle time reduction.

Another advantage offered by these machines is in the grinding of re-entrant camlobes. Grinding of re-entry type cam profiles with grinding wheel requires that smaller diameter wheels be used. This restricts the life of the wheel, making its use less cost-effective. With abrasive belts, the curvature of the belt can be controlled by changing the contact shoe diameter, so re-entry lobes of high negative curvature can be easily ground.

Higher Speeds

The current trend to reduce cycle time involves grinding at high wheels speeds. Machine builders in Europe and Japan are marketing high-speed cam-grinding machines with wheel speed capability of up to 200 m/sec. High grinding wheel speeds offer the advantage of longer wheel life, lower forces, and high removal rates. Higher metal removal rates at higher wheel speeds reduce cycle time.

A variation of the high-speed approach involves high wheel speeds, large depth of cuts, and low work speeds. This approach is similar to High Efficiency Deep Grinding (HEDG) and is essentially high-speed, cylindrical, creep-feed grinding.

Another approach uses a high-speed grinder with a pair of wheel heads. One wheel head uses a brazed, single-layer CBN wheel and is used to rough grind the lobes very aggressively. The other wheel head uses a small-diameter vitrified CBN wheel for finishing the lobes. This approach has been successfully used to grind re-entry type camlobes.

Vitrified bonded aluminum oxide wheels are still popular for grinding camshafts, but most CNC machines are now shipped with superabrasive wheels.

CBN & Beyond

The hardness, thermal conductivity and chemical inertness of CBN
have made it an abrasive of choice for production grinding of ferrous and aerospace alloys. Several bond systems—resin, metal, glass, and brazed—are available with CBN. Among these, the glass, or vitrified, bond system has proven to be the most popular. These bonds are rigid, free-cutting and have good form-retention. In addition, the porosity in these bonds can be controlled for more chip clearance and better coolant application at the grinding zone. Vitrified bonded wheels are easy to true and do not require additional dressing procedures.

The inherent brittleness of the vitrified bond system contributes to the self-sharpening action during grinding, but the brittleness also makes the wheels susceptible to chipping and breaking if used improperly.

One answer to this problem is a segmented wheel design, where individual segments are cemented to a steel or aluminum oxide core. Benefits include:

•Easy replacement of damaged sections
•Safety at high wheels speeds—up to 150 to 200 m/sec.
•Properties of individual segments can be measured and monitored so there is consistency along the wheel periphery and from wheel to wheel.
•Special wheel adapters can be resegmented and reused after the CBN layer has worn out.

There is also a ceramic aluminum oxide abrasive that's making an impact in cylindrical grinding operations. This elongated, high-aspect ratio abrasive can make a difference in high speed grinding of cast-iron camlobes. They provide high removal rates compared to a vitrified CBN wheel. The lower cost and single-point truing capability compared to CBN could make them excellent alternatives.

Tools of the Trade: Machining

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:50:00 +0000

TURN, TURN, TURN

The amount of things that you can do with turning may be surprising. At least that’s the sense one gets from spending time talking to the people at Fuji Machine America Corp. (Vernon Hills, IL). If there is any question of the company’s bona fides in relation to the work that it is doing in the auto industry, this should dispel it: According to company information, 64% of the lathes used by Toyota in Japan are from Fuji (the parent company is based in Chiryu City, Japan), and apparently there is a good working relationship between engineers from both companies such that there are mutually beneficial developments, developments that eventually make their way into commercial availability.

One of the ways that additional flexibility is being achieved in systems, including those built by Unova Manufacturing Technologies, is through the utilization of robots even for large-parts handling (note: this picture shows a system being tested; the actual installation doesn’t employ wood for purposes of fixturing).

Consider, for example, a camshaft cell that is available, one that meets “automation level C” within the Toyota Production System ranking of automation (ranging from A, fully automatic to D, which is essentially a standard CNC machine). In the “C” configuration, there is manual part load/unload and then fully automatic within-machine part handling. The camshaft cell makes use of a CE-30 mill and centering machine and a GN-30TTS four-axis turning machine. The CE-30 has double turrets for workpiece facing and centering; it can handle parts from 300 to 550 mm long. Then it is passed on to the GN-30TTS, which has two slides above the centerline of the bed. Through the use of CNC tailstocks, the machine is capable of handling various shaft lengths. A hybrid chuck grips the ends of the shaft wherever appropriate for the specific turning operations performed (e.g., edge- or mid-section turning).

Whereas a traditional crankshaft line is typically configured with Op. 10: centering; Op. 20: turning; Op. 30: turning; Op. 40: pin broach/mill; Op. 50: gauging, Fuji has a flexible alternative. Instead of dedicated equipment, there is the ability to change to other crank configurations in a reasonable amount of time. For Op. 10, the centering machine is replaced with a machining center (model YM-40) that performs facing on both ends and center drilling. Op. 20 is performed with a two-turret lathe (model GN-51TTS); the steps here including machining the front shaft OD and counterweight ODs, and facing the journals. The part orientation is reversed for Op. 30 (a double-hand gantry loader is used to transfer parts between machines); at Op. 30 there’s machining the rear shaft OD, threading, and journal finishing. Op. 40 is where there is some awfully clever turning performed (in fact, there is a patent pending). Here a GN-51TWS lathe is employed: it is capable of turning the eccentrics because the machine has adjustable offsets in the eccentric chucks that mean that off-center turning can be performed. Compared with the traditional dedicated broach/mill with special ring cutter, this alternative employs less expensive tooling and an overall lower investment cost. As for Op. 50, Fuji offers a variety of gauging alternatives, from a C-gage to laser.

CONSIDER THESE BENEFITS:
• Cycle time: improved 10%
• Machine cost: reduced 25%
• Total manufacturing cost: reduced 60%
• Machine space requirement: reduced 30%
• Power consumption: reduced 50% In addition to which, environmental concerns are greatly reduced.

Those are the sorts of benefits that can be achieved by utilizing hard turning in place of grinding for a variety of workpieces, ranging from gear blanks to wheel hubs. One of the big issues that can be overcome through the use of a turning machine in place of a grinder is the fact that the form tools ordinarily required for tapers, radii and chamfers aren’t necessary for hard turning equipment. Rather, because these machines can be programmed, tools can be rapidly oriented where required.

About that environmental issue: the folks at Fuji point out that this process can be performed without coolant, so the grinding sludge that’s characteristic of the alternative operation isn’t generated. Turning can have big benefits.

MAINLY MILLING

It wasn’t all that long ago that it seemed as though high-speed machining (as in milling) was all the rage—or at least something that consumed a lot of rhetoric. People were fascinated by the possibility of spinning spindles at high rates, rates in excess of 25,000 rpm at minimum, in order to remove metal more rapidly. And there were discussions of how this would lead to manifold benefits. The technology was pioneered in the aerospace industry, where the workpiece material tends to be aluminum. As the auto industry began its transition to aluminum blocks, heads, transmission housings, etc., it seemed like a natural transition to make: If the aero guys were running quite quickly on aluminum, then why not do it in powertrain plants?

Well, there were some issues encountered, notes Richard A. Curless, director of Research & Development, Unova Manufacturing Technologies (UMT), a division of Unova, Inc. (Fundamentally, UMT combines the capabilities and products of Lamb Technicon and Cincinnati Machine.) For example, consider the nature of machining in the aerospace industry. There are large workpieces (e.g., wing spars) that are milled and contoured. These operations are long, as plenty of material is removed from the billets (as Dr. Phil Szuba, director of R&D for Lamb products at UMT, points out, they’re removing about 90% from a billet to end up with a spar), so working with a high spindle speed can be exceedingly helpful. But Curless notes that in auto, “There’s a lot of starting and stopping.” As in: Drill. Stop. Tap. Stop. One of the burgeoning characteristics of more and more automotive parts is that they are being cast to a near-net shape, which requires comparatively less metal removal. It is one thing to keep a high-speed spindle running for a long time, generating lots of chips, a la aero. It is entirely another to put them through the sort of duty cycle that goes on in auto. Which can lead to the need to change spindles more frequently than would be liked, for, as Curless notes, one of the key issues in automotive machining is uptime, with particular attention being paid to mean time to repair (MTTR). So, according to Szuba, a spindle speed in auto of 16,000 rpm is fairly common (achieved through the use of grease-pack bearings that provide reliability), as compared with the 30,000 to 40,000 rpm that might be run in aero. What’s more, given the faster pace of car making as a whole compared with the number of aircraft built, the fundamental focus is not merely on the speed of the spindle, but on the entire cycle time. Which includes the time required to load and unload parts.

This mill can be deployed in machining centers as well as mill-turn machines for serious cutting.

Although there is a natural assumption to think something along the lines of “Machines/Metal,” Curless points out that electronics developments—both in terms of software for parts programming and optimization, as well as vector drives and high-speed servos—are having a huge effect on the nature of machine tools and their capabilities. Speaking of the former, Curless notes that there is greater modularity of the equipment, which leads to the sourcing of components from a variety of sources (e.g., components for a machine, say way systems, might come from any number of countries, ranging from Japan to Switzerland). And speaking of contributions of things like the drives, servos and controls, he points out that the traverse rates of machines have been marching forward at a considerable rate during the past several years, going up to around 80 m/min today, with an acceleration of at least 0.5 G being almost an expectation.

One of the characteristics that is keenly sought by both OEMs and suppliers alike in terms of machining capability is flexibility, the former’s interest deriving from the heavy investment in major machine lines, and the latter being concerned with the consequences of losing programs. While this has been a discernable trend for the last few years, Szuba says the extent to which this is occurring is somewhat surprising, as in even performing applications like gundrilling crankshaft oil channels on flexible CNC machines rather than on dedicated pieces of equipment.

Flexibility in machine operation is one thing. Making it easy for an operator to take advantage of it is another. This cylindrical grinder addresses both.

A DIFFERENT GRIND

Those who have a need to (1) perform cylindrical grinding, both internal and external, and (2) find themselves doing so on various parts should be interested in the capabilities of the Studer S151cnc, which has a swing diameter of 350 mm and a between-centers grinding length of 350 mm. There are two independently programmed grinding spindles on the turret head so that there is the ability to rough and finish grind in a single setup. Because changing from one part to another means a whole lot more than adjusting workholding, the machine has a Fanuc 16i digital control loaded with Studer Pictogramming, which is a step-by-step approach for operator programming. The machine is available from United Grinding Technologies (Miamisburg, OH).

TOUGH CUT

Need to mill some heavy metal—as in steel, stainless steel, or even heat-resistant super alloys? Check out the CoroMill 390 long-edge milling cutter from Sandvik Coromant (Fair Lawn, NJ), which features a hardened-steel cutter body (in diameters from 40 to 200 mm) and handles 18-mm long inserts. The cutter can mill depths up to 3.9-in. and can provide 90° corners.

Designed and engineered for use by automotive suppliers who need a sizable machining center at an economical price.

BIG BUT FAST

Although the a81 horizontal machining center is big—it has a 630-mm square pallet, a standard 50-taper spindle (capable of 10,000 rpm), a payload capacity of 1,500 kg, and X-, Y-, Z-axis travels of 900 x 800 x 900 mm—it is a quick machine, as well. That is, it provides a rapid traverse rate of 60 m/min, as well as the same speed for the feedrate. There’s a 40-tool magazine that works in conjunction with an automatic toolchanger that handles tools with a 1.7-sec. tool-to-tool time. Yet the a81 from Makino (Mason, OH) has a comparatively compact footprint: 3,460 x 5,370 mm.

DOUBLE UP

By putting two spindles on a single base and by providing plenty of tools, productivity in turning can be realized.

Optimal working space is a fundamental characteristic of the TWIN 42 turning machine from Gildemeister Group (DMG America; Schaumburg, IL), as it has, as its name implies, twin spindles. In addition, the machine has 12-station turrets for handling a good variety of tools, all of which can be driven. The machine has a turning diameter of 42 mm and can handle 580 mm between centers. Four-axis machining can be performed on either of the spindles or there can be simultaneous two-axis machining on both spindles. In addition, there is the capability of automatically transferring a workpiece from one spindle to the other, thereby providing the means to do full processing without manual intervention.

Simple addition for improved production from small Haas lathes.

UP OUTPUT

For those of you who have a small lathe from Haas Automation (Oxnard, CA)—such as the SL-10 turning center—and are looking to up your production, check out the new Barr-100, pneumatic, automatic bar feeder that the company has developed for its small machines. It can handle bars up to 1-in. diameter. When used in the pneumatic mode, 6-ft. long bars can be automatically loaded. This additional productivity is cost-effective: the Bar-100 has a retail price of $2,995.

Machining: Tools for the Trade

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:44:00 +0000

What's It Called? The ANS-3100P from FUJI Machine America (Vernon Hills, IL; www.fujimachine.com).

What Is It? A hard turning lathe.

Configuration? It's a modular machine that features one spindle, one turret, and a four-axis swing arm robot for part handling.

Key Specs? The spindle has a 20-hp motor. The turret has eight positions. A Fanuc control is deployed.

Considerations? Hard turning can work as an alternative to grinding. The machine is built as a module, so the potential for lines to be created out of several is there (especially given the deployment of robotic automation).

What's It Called? The EWB-AL aluminum tooling system from BIG Kaiser Precision Tooling (Elk Grove Village, IL; www.bigkaiser.com).

What Is It? Ultra lightweight automatically balanced precision boring heads for diameters ranging from 3.937 to 8.000 in.)

Key Specs? The tooling system uses two different heads to cover the entire diameter range. It is designed for cutting speeds up to 6,600 sfpm. There's micrometric adjustment via dials that are graduated in 0.0005-in. increments as well as a Vernier scale that permits setting to 0.0001-in./diameter.

Considerations? Several. Because these heads are made of a hard-coated high-tensile aluminum, their weight is one-third that of steel, then when you add other tooling elements (e.g., extenders) that are also aluminum, the total tooling weight can be half of that of ordinary tools, which is an aid during automatic toolchange procedures. (The hard coating, incidentally, helps extend tool life.) The balance that is provided by the adjustment is particularly important for boring at high speeds with polycrystalline diamond (PCD) or cubic boron nitride (CBN) tools, especially as this facilitates improved surface finish.

What's It Called? The Variaxis 730 5X five-axis vertical machining center from Mazak Corp. (Florence, KY; www.mazakusa.com).

What Is It? A machine with a 150º tilting table that allows simultaneous five-axis machining without the need for re-fixturings or additional machines.

Key Specs? There is a 50-taper spindle. Maximum spindle power is 40 hp and 387 ft-lb of maximum torque. The top speed: 10,000 rpm. The table on the standard single-pallet machine measures 24.8 x 19.7 in. The rapid traverse rate in the X, Y, and Z axes is 1,575 ipm. The standard tool magazine holds 30 tools. The control is via the conversationally programmed Mazatrol Fusion 640M CNC.

Considerations? Mazak brought out its first generation Variaxis machine in 1999, and has been pursuing continuous improvement since that's so far culminated in this machine. Because it has a 50-taper spindle, it can better perform heavy-duty roughing ops on castings and forgings. Compared with the 40-taper version of the machine, cycle time reductions of 24% on duplicate parts have been realized. Another improvement area is environmental: the amount of air consumed during machining is reduced 50%, a grease lube system reduces waste oil by 57%, and coolant life is boosted by 50% because there are no tramp oils from the linear guide lube system.

What's It Called? Servo and Spindle High-Response Vector Software Version 4.(HRV4) from GE Fanuc Automation Americas (Charlottesville, VA; www.gefanuc.com).

What Is It? HRV4 is as its name implies servo and spindle software that takes advantage of the abilities of the mechanisms they control such that high-speed and high-precision machining can be preformed. In this case, they're talking about the nanometer level of interpolation.

Key Specs? The DSPs used today allow blazingly fast servo feedback data, so the Servo HRV4 closes the current loop in 31.25 µs, the velocity loop at 62.5 µs, and the position loop at 250 µs. The Spindle HRV4 uses a dedicated spindle process to achieve a 12 kHz PWM frequency.

Considerations? Why not make the most of your GE Fanuc servos' and spindles' abilities with the latest software from GE Fanuc?

What's It Called? The VF-6SS vertical machining center from Hass Automation (Oxnard, CA; www.haascnc.com).

What Is It? A vertical designed for high-volume operations (or when exceedingly low cycle times are required: the “SS” in the designation stands for “Super Speed”).

Key Specs? It has a standard 30-hp 12,000-rpm inline direct-drive 40-taper spindle. The machine travels are 64 x 32 x 30 in. High-pitch ballscrews and high-torque servos combine for rapids of 1,200 ipm Y and Z and 900 ipm X. There is a 24-pocket side-mount automatic toolchanger that makes changes in 1.6 seconds. Other features are an automatic chip auger and a programmable coolant nozzle.

Considerations? Speed is good, but at the end of the day (or machining operation to be more specific), quality matters. This is one reason why the direct-drive spindle setup is important. That is the system is designed to minimize vibration and heat, both of which can have negative effects on surface conditions. In addition, noise is reduced, which certainly improves the conditions for the machine operators.

What's It Called? The FH-SX horizontal machining center from Toyoda Machinery USA (Arlington Heights, IL; www.toyoda.com).

What Is It? A machine that's designed—specifically via the design of the column—to provide the sort of rigidity required to cut steel and other ferrous materials like a boxway-style machine yet provide the kind of speeds more characteristic of a high-speed machine—i.e., 20% faster than a boxway machine.

Key Specs? Features a 50-taper, 40-hp, 6,000-rpm spindle that's flanked by a ballscrew and motor on each side so as to double the driving force on the Y axis. TheFH550 SX version has a work area that's 29.53 in. X, 31.5 in. Y and 33.46 in. Z. The rapid traverse rate in all three axes is 2,362 ipm, and the acceleration is 0.7 g. The pallet size is 21.65 x 21.65 in. The machine offers a linear positioning accuracy of ±0.00012 in. and a linear repeatability of ±0.00008 in.

Considerations? When don't you need a combination of speed and accuracy in machining?

What's It Called? The NVG 1500 DCG vertical machining center from Mori Seiki (Irving, TX; www.moriseiki.com).

What Is It? A compact machining center that is designed to be able to achieve high-speed, high-precision machining operations.

Key Specs? The machine is just 33.5-in. wide and has an overall footprint of just 17.2-ft2. Designed for small-part production, including such things as electrodes, it has a maximum spindle speed of 24,000 rpm. The travels are 150, 150, 200 X, Y, Z, respectively, and the rapid traverse is 15,000 mm/min. It handles HSK E32 tools. Tool change chip-to-chip is 3.5 seconds. The cutting speed is 15,000 mm/min. The machine is capable of providing a roundness of 0.8 µm, which is ordinarily achieved with the assistance of a lathe, not only a machining center.

Considerations? The machine uses the “Driven at the Center of Gravity” approach that Mori Seiki has pioneered, which essentially means that the company deploys two parallel ballscrews along the spindle axis so that vibrations are minimized. This leads to high precision. In the case of this machine, the precision is further assured through the use of minimizing thermal displacement by passing coolant through the motor bracket.

How To Machine Light Metals

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:42:00 +0000

While die casting experts are working on producing die cast parts to net shape, machine tool and machining system builders are busy producing machines that remove the not-so-net excess more efficiently. These machines are different from the ones designed for heavier metals.

First of all, the amount of power needed for working the lighter metals is much less than with cast irons or steels. Secondly, metal removal rates can increase substantially. Surface feet per minute (sfm) values are much higher than with heavy metals (up to 1200 SFM with uncoated carbide). The exception to this rule is magnesium. "You have to submerge the part, and go much slower," explains John S. Klimach, president & CEO at Ex-Cell-O Machine Tools, Inc. (Sterling Heights, MI). "If you don't the part will catch fire."

Machines such as Ex-Cell-O's XHC 241 shown in action here are specifically designed for the high-speed metal removal rates that are possible with many of the light metals.

Mark Tomlinson, vice president of engineering at Lamb Technicon Machining Systems (Warren, MI), feels that there's also a basic change in tooling philosophy between cast iron machining and aluminum machining. "The tooling technologies that are used and the types of tools and inserts that can be used are different," he explains. "What that corresponds with is actual tool life. In cast iron, you're looking to get one or two shifts worth of production out of a tool. With aluminum, you're looking at a whole year's worth." But to actually achieve this kind of productivity, the machine's spindle has to be much more robust. Why?

For starters, spindles require much higher speeds, and less low-end torque than when machining steel or other materials. And they have to be stiffer, to hold tolerance under the faster conditions. Miles Arnone, president and COO at Boston Digital Corp. (Milford, MA), recommends using HSK tapers for added rigidity and accuracy. He also recommends that if very fast tool changes are required, closed-loop motorized spindles should be used to reduce the rotating inertia.

The higher spindle speed also lends to increased frictional heat in the bearings, so a cooling system has to be added. And since light metal machining is not a dry operation, the spindle has to be well sealed against coolant infiltration.

But the spindle isn't the only factor to take into consideration. Here are a few more:

Coated-carbide tools, such as TiAlN, should be employed to extend tool life and to increase SFM levels up to 5,000 surface-feet-per-minute.

Everyone is "Wowed" by high feed rates, but the ability to quickly accelerate or decelerate is more important than maximum feedrates when machining 3D contoured surfaces. CNC features such as gain switching (changes servo parameters on the fly) or contour optimization (lets you set a contour tolerance and automatically manages feed rate) are also important as axis feed rates rise when machining light metals.

Because speeds and feeds are so high, thermal growth can be a major problem when working with light metals. Seek machines with good thermal control systems, and glass scale feedback on all axes. A high-performance machine should provide thermal control of the spindle and major structural elements, such as the column in a VMC. For high precision applications (tolerances better than ±0.0005"), temperature controlled coolant should be considered as well.

Chip removal can be a big issue when working in light metals such as aluminum. Because so much material can be removed in a short period of time, it is important that the machine tool be well designed for chip evacuation.

Even though the cutting forces to machine aluminum are less than when working with steel, for example, it is still very important to have a stiff, well-damped machine. While cutting forces are lower, dynamic forces due to accelerations and decelerations are very high.

But with Magnesium…

Not Quite Metal?

DSC aluminum from Chesapeake Composites (New Castle, DE) is an alloy, but isn't quite all metal. Instead of the traditional materials used to strengthen aluminum (like nickel), DSC contains ceramic compounds. Traditionally, adding ceramic to aluminum has created an alloy that is difficult to machine (very abrasive), and expensive to cast. The patent-pending process Chesapeake has developed more evenly disperses the ceramic particles, which are smaller than the ceramic grains used previously. The process also brings the price of billet down to around $3 per lb., as opposed to the $4 or $5 per lb. cost usually affiliated with ceramic alloyed aluminum.

It's much easier to see the uniform disbursement of the ceramic in this up close and personal look as DSC Aluminum.

From a production standpoint, the addition of the ceramic leads to better strength at elevated temperatures, as well as more controllable thermal expansion, so post-casting machinability is much easier. Standard carbide tooling and aluminum oxide grinding wheels can be used, rather than diamond tools and CBN wheels. Better stiffness and ductility are also among the alloy's qualities. DSC Aluminum can handle temperatures of up to 600°C for long periods of time, opening up powertrain and engine component possibilities usually reserved for cast irons and steels.

These suggestions and observations apply to aluminum machining very well, but if you tried to do the same things with magnesium, you'd be in big trouble (remember Klimach's warnings of fire?). Safety is the big issue here, and there are a few ways you can safely machine magnesium.
•SLOW DOWN. The high speeds you enjoy with aluminum create heat, and heat is not good here.
•Water-based cutting fluids are okay, but use a cutting fluid with a high pH-value. This will reduce the amount of hydrogen gas produced as the water and magnesium react.
•Since hydrogen gas explodes under pressure, maintain good ventilation to dissipate any gas that may be produced.
•If a fire does occur, DO NOT throw water on it, the chemical reaction will actually cause the fire to get bigger. Smothering the fire is the better option. Klimach mentioned one company that kept a barrel of cast iron chips near by when machining magnesium. If fire broke out, they'd shovel the chips on top of it.
•The National Fire Protection Association (NFPA) adds these safety guidelines for handling chips: separate the fluid and chips using a centrifuge system, and do so as soon as possible after machining. Letting the chips sit around lets the fluid and magnesium interact further, increasing the potential for fire. Also, make sure the storage containers are nonflammable, ventilated containers. If not properly ventilated, the possibility of dangerous hydrogen concentrations increases. Store the containers in isolated areas so that if a fire or explosion does occur, it is away from employees, machines, and other flammable materials.

These suggestions for machining magnesium may seem a bit alarmist and silly, industry-wide, magnesium is considered a "problematic" metal to machine. Recent developments in magnesium alloys have somewhat dampened its fiery nature without sacrificing its light weight charac-teristics, but users should still be cautious.

Of course, if the diecasters have anything to say about it, suppliers won't have to worry about the considerations and concerns of machining excess material from light metal parts. After all, you don't have to remove anything from parts that are "nothin' but net."

Nothin' But Net

Casting parts to net size is something the automotive production world is eagerly trying to achieve. Not only would parts producers save lots and lots of time, but lots and lots of money, as well. The castings aren't quite there yet, but advances in technology and innovative new techniques are driving things closer to that so far elusive, but not impossible absolute net-shape part.

Even before metal is poured into a die, flow control is a factor. Selcom, Inc. (Southfield, MI), develops laser-based pouring systems for all sorts of molten metal applications. It's not something component suppliers typically think about, but the quality control system surrounding how the metal is poured into the die is something that effects the overall quality of the casting they have to work with. The LaserPour systems Selcom develops use sensors to keep an eye on how the metal flows into the die, bringing the resulting casting even closer to net shape.

They track flow of the metal into the mold, and mold levels, resulting in more accurate physical dimension and grain structure within the mold. With high-speed resolution at about 0.006 in., and a data sampling rate of 16 kHz, the sensors read data fast enough to stop the automated system from over pouring, pouring too slowly, or pouring too quickly, all of which has an effect on the part. The laser feedback loop also allows accurate measurement without being effected by plant conditions (temperature and light changes, etc.).

Putting On the Squeeze

This sensor system used in the LaserPour is just one of the examples of advances in technology driving improvements in the quality of light metal casting.

Moving from process controls to processes, one that stands out is the squeeze-cast process for producing aluminum parts called Hi-Cast from Amcast Industrial Corp. (Dayton, OH). It uses a coaxial double piston pressure system for delivering molten aluminum to the die. The system—developed mainly for multiple-cavity die casting—consists of a shot sleeve that tilts to receive the aluminum from a ladling system.

After receiving material, it swings back into sync with the die, where the primary piston squeezes the metal into the die cavity. After the casting solidifies, the piston advances again to eliminate any cavities caused by shrinkage. At this point, the second piston advances to continue both filling the die with aluminum and applying pressure to eliminate shrinkage cavities. Quick cooling rates and consistent pressure provide higher fatigue strength to both thick and thin areas of the die. The higher consistency of die coverage also brings the part nearer to net shape, reducing the amount of machining needed after the die is cast.

Making It At Mazda

At Mazda, experimentation with net shape parts has resulted in the development of a process that introduces air pressure into the mold. Called "Air-Assisted Infiltration Process," it reduces the amount of pressure (from 1,000 atm to 10 atm) and energy needed to introduce metal into complex dies. This process has even been used successfully with dies with a divided core, a place where even squeeze casting proved inefficient.

According to some, casting magnesium is even easier than aluminum. The thixomolding process is said to produce net-shape parts in a single setup. The process, used at Thixomat, Inc. (Ann Arbor, MI), is similar to plastic injection molding. Magnesium feedstock is heated until the metal is semi-solid. The resulting slurry is injected into a preheated metal mold to make the part. The semi-solid molding process is particularly well-suited to magnesium since its creep properties do not lend well to pouring.

Several companies, including Mazda, are interested in the process. Especially beneficial is the resulting net-shape parts, which seem to retain desired structural and mechanical properties, and come out of the die without needing any post casting machining to bring parts to net shape. This is especially desirable since finish machining magnesium is a difficult and expensive process.

How to Choose and Size the Right Metalworking Filtration System

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:41:00 +0000

In today’s aggressive global market, modern moldmaking competition is fierce. You must deliver high quality molds on time at competitive prices. Just as the high-tech CNC equipment that molds are machined on must be state-of-the-art, the coolants and oils that are used in the various machining processes must be maintained to deliver quality parts on a consistent basis—the tolerance and surface finishes on part number one must be the same as part number 5,000.

The focus of this article is on filtration for coolant and oils used in the machining processes with emphasis on grinding. The objective is to increase throughput and maintain part consistency. Whether it is surface I.D., O.D. or cutter grinding, the quality of the coolant, oil and its cleanliness will have a direct bearing on the tooling, wheel and workpiece that is being machined to precision specifications.

Critical Coolant/Oil Functions
The coolant or oil that is used to cool the process in the grinding application serves these critical functions.

Cooling the wheel and part from the heat that is caused by the grinding process, this controls thermal distortion which is critical especially with tight tolerances.
Provides lubricity to the area where the wheel contacts the workpiece.
Flushes away the removed stock as well as the abrasive that has worn off the wheel and carries these particles away from the workpiece back to the coolant tank, usually through a band or rolled media filter to catch the fines before pumping the process once again.

Coolant Challenges
The problem with this elementary type of filtration is that, at best, it only catches what you can see (the smallest particle the naked eye can see is 40 microns). It is what you cannot see that has a detrimental effect on your product and cost of machining. These particles are very small and are measured in microns—one micron is 0.000039 of an inch.

One filtration system servicing two precision grinding machines. Images courtesy of Ebbco.

As your process continues, the concentration of these smaller particles becomes higher and you start to lose the effectiveness of your coolant. First you start to lose lubricity along with the effect of generating more heat at the cut, which increases wheel wear on the grinder, and in turn increases the need for wheel dressing that also adds fines to the coolant. The heat itself can cause the surface tension of the parent material to change showing noticeable stress cracks; therefore, causing the polishing and wear characteristics of the tool not to be uniform.

A Properly Engineered Filtration System
With a properly engineered filtration system the coolant life can be increased exponentially, which also is an environmental and disposal issue of its own. The wheel life is greatly increased and the machine tool itself is kept cleaner thus increasing the useful life of the machine.

Sizing a filtration system is an engineered process in which the size of the sump, the gallons per minute of flush rate and the heat load of the operation must always be accounted for. It is not a simple case of ordering a bag vessel from a catalog and installing it on the machine.

Filtration System Sizing
Type of Fluid
First and foremost, the type of metalworking fluid must be determined: neat oil, water soluble or synthetic water-based coolant. Once the fluid is established, the volume of coolant must be determined by the amount of flow (gallons per minute) needed at the process times six.

For example, a grinder flushing at 30 gallons per minute will require approximately 180 gallons of coolant. This may differ based on very light or very heavy stock removal.

Heat Exchanger
Stock removal also will affect the need for additional heat dissipation in the form of a heat exchanger. A heat exchanger can be as simple as a braze plate or shell and tube heat exchanger plumbed into an existing cooling tower in the facility, or to a stand-alone refrigerated liquid chiller. Sizing of such a unit is achieved by calculating the total number of BTU/HR that must be removed.

Central filtration system providing clean (5 micron) and cool (70°F) grinding oil.

Cleanliness Level
Last, but not least, the proper method of filtration is determined based on the prescribed cleanliness level needed. Coolant filtration from one micron to 25 microns needs a medium to high-speed centrifuge or barrier filter (i.e., cartridge or rolled media filter is necessary); 25 microns and above can be achieved with centrifugal separation (no filter media); and, neat oils require a centrifuge or barrier filter.

Summary
When determining the type and size of the filtration system necessary for a new or existing machine, many factors need to be considered to select the correct filters and the best coolant. The final decision is based on the level of cleanliness and temperature of fluid necessary to produce parts on a consistent basis. Coolants and oils used in the machining process for grinding have a direct relationship to the quality of the machined parts. Only after the required quality of the produced parts is known can the correct system be installed. The selection of the filtration system is integral to the total machining process.

How to Select and Use Your Vertical Machining Center

noreply@blogger.com (alit76) — Fri, 31 Aug 2007 13:37:00 +0000

Dramatic changes continue to sweep through the North American die/mold industry. Overseas competition is forcing North American manufacturers to re-evaluate their processes and manufacturing techniques to reduce costs and minimize leadtimes.

These changes are causing a primary shift in manufacturing applications toward more automated techniques and process-driven approaches. This in turn is changing the way in which die/mold shops are selecting and using vertical machining centers (VMCs). This shift is forcing a change in the capability that these shops require from their machining centers in order to remain globally competitive.

Competitive Shops
The most competitive die/mold shops today are adopting techniques that allow them to reduce or eliminate bench work, polishing and the fitting of mold components. For these shops, first-part sampling has moved from a process of sampling, adjustment and re-sampling to one requiring no adjustments. This is achieved through implementation of techniques such as cutting parting lines and mating surfaces to zero or negative stock.

Machining to very tight tolerances between mating components is mandatory, so that no hand fitting is required. It is possible to achieve this with parting surfaces, insert to pocket fits, as well as in 62-64 HRc die components.

Vertical machining is ideal for plastic electronic telephone enclosure molds that have tight component tolerance requirements. Photos courtesy of Makino.

To achieve this level of accuracy and surface finish; however, competitive shops need to first consider the true capabilities of their VMCs. This is not limited to what a spreadsheet indicates the performance of the machine will be, but by verifying the real accuracy and surface finish capabilities that the equipment will deliver.

This new level of quality, achieved day after day without a lot of adjustments and manual maintenance of the process, is essential to remaining globally competitive. The best VMCs available today allow a shop to implement solutions-based techniques without intensive process monitoring by the floor employees.

Performance, Not Specs
VMCs can no longer just be selected by analyzing a spreadsheet that compares spindle horsepower and torque, X/Y/Z travels and purchase price. In order to achieve results that will be competitive in the global market, shops must consider aspects of machine performance that will produce extremely high accuracy and superior surface finish requirements.

Spindle design, thermal stability and the construction and stability of the machine become more important aspects to consider in a VMC than horsepower and torque values. Spindle design is a critical component in achieving a perfect fit between components, without manually fitting those components.

High-performance spindles will maintain extremely stable Z-axis accuracy. This requirement is paramount toward the elimination of manual fitting. If a spindle is not capable of maintaining very tight Z-axis accuracy, there will be no possibility of achieving a machined fit between mating components.

The best VMC spindle systems available on the market today have cooling systems that thermally control the internal workings of the spindle as well as the outer housing. This removes the heat at the source and eliminates the need for complex software or hardware systems to predict and compensate for thermal growth.

Additionally, the chillers responsible for stabilizing the spindle must be variable capacity units and be very accurate. Chillers need the capability to continuously monitor the VMC spindle temperature and adjust the cooling capacity. These should maintain temperature within one degree Celsius in order to provide the level of stability required to eliminate manual adjustments to components during assembly of the die or mold.

Once a highly stable spindle is used, then automatic tool length measurement systems can add the next level of accuracy to achieve very accurate tool-to-tool blends. This in turn allows the use of highly accurate tooling to achieve the maximum results in quality and surface finishes.

Vertical Designs
Machine design needs to follow modern technology philosophies. A traditional VMC is not designed with attention to heat build-up and volumetric stability.

At feedrates of 20 to 40 inches per minute, this was not a concern. With the capability today of machining at hundreds of inches per minute, machine casting and design demands have dramatically changed.

Thermal stability needs to be designed and built in to the casting of the VMC itself. With the high rpm spindles and high torque servo drives presently available, these components can induce significant heat into the machine casting.

State-of-the-art technology, such as cell phone molds, are ideal for the attributes of vertical machining centers in reducing and eliminating benchwork.

Designed incorrectly, a casting can suffer significant thermal deformation. This will cause a collapse of volumetric accuracy, forcing a shop to invest in costly and continuous manual adjustments of the machine in order to get machined components to fit correctly. This then causes a '"domino effect" on extending leadtimes and raising costs to complete a mold or die.

Designed with these issues in mind, however, today's VMC can maintain extremely accurate volumetric accuracy over very long cycle times required. This will help die/mold shops deliver quality components that require no manual finishing or fitting.

High-Performance CNC
Once the structure and mechanical components of a properly designed, thermally stable machine are in place, then a high-performance CNC control is required to fully implement the capabilities of modern CAM systems and tooling. During acquisition of a VMC close attention should be paid to how the control system processes and handles the data.

The control must be focused and designed to provide maximum accuracy in order to eliminate fitting and benching requirements for molds and dies.

Many controls today convert the supplied toolpath data from its original data into a spline, such as a NURBS-style toolpath. This conversion process can help a machine tool move through complex geometry at very high feedrates that are impressive to watch.

However, such a conversion also can induce excessive inaccuracy into the cut, causing manual fitting to be required. Look for a control that obeys the geometry that the CNC program provides, and one that will take action to obey that geometry when the feedrate and servo acceleration limits are exceeded.

Don't Stop There
With a technologically advanced machine design and rigid construction for high-performance usage, and with a highly stable spindle and a high-performance control, you can be sure you have a VMC that will provide dramatic cost and leadtime reductions.

But, it is not enough to stop here and expect to get these results. With the properly selected VMC in place, attention must be paid to CAM systems and tooling as well.

Consumer products, such as the lids to drinking cups, require superior surface finishes with no polishing that can be provided via vertical machining.

Recent CAM system advances are key to achieving maximum results with a technologically advanced VMC. The ability to produce very accurate toolpaths with very tight chordal tolerances are critical.

They also provide the flexibility to allow the user to modify lead-in/lead-out, cutter engagements and other details of the toolpath. These issues become very important to achieving reliable, repeatable results, especially in an unattended manufacturing system.

Balanced toolholders are critical to achieving both accuracy and surface finish requirements. The use of cutting tools with highly accurate form control cannot be overstated.

High quality cutting tools typically have tolerances of 0.0005 inches, which are greater than those often required in the die/mold industry today. For even more precise requirements, cutters with tighter tolerances also can be used.

Getting Results
Achieving dramatically shorter leadtimes and reduced manufacturing costs in vertical machining are mandatory requirements to competing in today's global die/mold market arena. However, in order to succeed it is necessary to review all current manufacturing processes.

Question whether or not there is an innovative new way to reduce costs in your operations and to take advantage of advanced vertical machining technology. This will require important and continuous research in finding the finest new products and innovations available.

This research will bring additional efficiencies to your die/mold operations, particularly due to vertical machining advancements. Being proactive in the global market will allow shops to maintain a global competitive advantage.

Getting to Know Your Machine Tool

noreply@blogger.com (alit76) — Thu, 30 Aug 2007 17:21:00 +0000

When looking to purchase a machine tool for your shop, it is vital to choose a machine tool supplier that designs, engineers and builds its own components. That way you are ensured of optimum performance at greater accuracies. And—if something should go wrong—your supplier can quickly get to the root of the problem since they were in charge of everything that went into that machine.

So before you buy, here is what you need to know about the six core components of a machine tool.

1. Automatic Tool Changer (ATC)
It is important that the ATC exchanges tools within the spindle as quickly as possible. By matching the drives and the motors the ATC arm hands off the tool to the spindle accurately. A good ATC system has the ability to decrease downtime and increase productivity.

2. Motor/Drive/Encoder
Once again, if you are having parts move, you need to match the best motor for that machine, and the best drive, and the best way to achieve this is to ensure your supplier is not using any outside components. They should design and build all of the electronic drive boards, electric motors, and absolute encoder systems that provide feedback to the control. Sophisticated communication within the system allows the machines to deliver some of the highest metal removal rates alongside positioning repeatability in the single digit micrometer range.

3. Base Casting
Since the base casting is the foundation of the machine center, the heavier and more rigid, the better. It may cost more, but the strength and durability will minimize vibration. If you have vibration, you are not controlling where the waves are going to be mounted. Tough machines will absorb the toughest horsepower cuts with the greatest accuracy.

An example of a vertical machining center with six core components: ATC, motor, casting, control, turret and spindle. Image courtesy of Okuma.

4. Control
The control is the heart of the machine tool. It is telling the machine what to move, where to move, and how exactly to achieve the optimal cutting time, speed and feeds that you need. The blend of electrical and systems engineering give the controls a full range of power, heightened accuracy and ease of operation—turning data quickly from a CAD source into finished parts at the least cost per component. The machine tool supplier needs to be in control of their design for optimal matched control with the optimal matched machines.

5. Turret
The machine tool supplier should create each turret to match a specific machine and should capitalize on available horsepower and efficiently remove material without sacrificing accuracy. A durable turret increases the strength of the cutting process. Suppliers that design their own turrets enable them to only require one drive for the turret and milling function on the tool. Once again, if you have parts that are moving, who better to control it?

6. Spindle
The spindle is one of the most critical elements of the machine tool. A stable spindle incorporates the drive motor with the spindle—taking into account rigidity, lubrication and power, and also ensures consistently accurate finished parts and predictable productivity. Again, its design—with the optimum rpm rotation in mind—will give you the best cut and accuracy for that machine. Machine tool suppliers who design their own spindles can rebuild and support the spindles, extending the life and productivity of your machine.

One Source
Make sure the supplier designs, engineers and builds all of the machine’s key components so the system can be matched better. By using one source you can ensure the communication will be correct between drives and motors and the control itself.

Die Cast Dies: The Benefits of a Proactive Tool Build

noreply@blogger.com (alit76) — Thu, 30 Aug 2007 17:13:00 +0000

With the advent of a troubled auto industry and ongoing trade issues it’s no secret that the business of producing die cast parts has become increasingly competitive. There is now much less tolerance for downtime or high scrap rates. And all too often, the source of production headaches comes from porosity present within the part.

It should first be noted that every die casting tool needs air evacuation. Today, with advances that have occurred, a strong case can be made for using vacuum technology over a conventional vent system to help alleviate porosity and other die casting issues. Two basic styles of vacuum approaches currently exist: (1) valve and (2) valve-less. This article will evaluate the benefits derived from both.

Upon evaluating these advances, more and more die casters are moving from
traditional venting to the correct application of vacuum technology. Why? Because vacuum is an assistive approach that ultimately helps to create better quality parts.

Vacuum Technology
Die casters will often say the choice between conventional venting and vacuum is based on part requirement and customer preference. However, making a cost comparison before deciding might leave the customer pleasantly surprised. Consider the following benefits

Made of pre-hardened H-13 tool steel and salt bath nitrided, this style of economy series vent blocks is standardized and ideal for short runs and prototyping. Images courtesy of Progressive Components.

Conventional venting is less effective than vacuum because there’s not enough total vent area for the cavity to evacuate efficiently. In venting, the press alone does all of the work, whereas a vacuum system assists the press in evacuating the cavity. It’s more efficient and there’s less wear and tear on the machine and tool, saving maintenance time and costs, not to mention part fallout.

Vacuum systems reduce the amount of gas porosity in the casting. This is a major benefit because although all porosity cannot be eliminated, most of it can be with vacuum assistance.

Three different types of porosity are created during the die casting process. One is simply air in the metal feed system and die cavity. The second type is a gas that’s created when the hot metal that’s being injected hits the lubricant that’s being used. Vacuum technology helps reduce these types of porosity. The third type of porosity is shrinkage. Unfortunately, process control is a more critical factor in minimizing the problem, and vacuum technology has little influence on this.

“Vacuum vents have helped us reduce poor fill and porosity scrap rate and produce a better quality part,” reports Rod Dunn, Inverness Casting Group, (Dowagiac, MI). As for technical assistance with selecting the proper technology? “It’s been appreciated!”

Other benefits of vacuum technology include improved surface finish and improved mechanical properties of the metal being cast. Vacuum technology reduces out gassing, thereby improving painting and plating quality as it reduces the out gassing. Additionally, the higher the density of the casting, the better the weldabil-ity and leakage factors will be.

These standardized valve-less vacuum blocks offer reduced porosity and scrap, improved casting integrity and an improved surface finish.

Location of porosity is critical. If air is near the surface when the parts heat up, the air will expand and could cause holes or blisters on the surface during powder coating or plating. The use of vacuum blocks means there will be less scrap because you can decrease the porosity inside the part, plus you can prevent other problems that can arrive downstream during machining.

“We had a four-cavity aluminum disk mold, where the part was simple and the initial inspection was positive,” describes Denny Schlager, Twin City Die Castings (Minneapolis, MN). “But during the machining process, grooves were cut across the face of the casting and we were experiencing a high rate of porosity at the deepest machined sections. This caused an 80 percent rejection rate!”

Twin City had to do something: “We installed two valve-less vacuum blocks. One block serviced two cavities and with the help of technicians from blocks supplier Midland Technologies, a proper runner was engineered. They also advised us in the setup and operation of the system. This improved our acceptance rate to more than 95 percent.”

In today’s competitive marketplace, where die casting is taking on more and more complexity, it’s hard to deny the advantages of using vacuum technology to increase up-time and lower costs.

Valve vs. Valve-less
Following are some notable comparisons between valve and valve-less vacuum block systems.

• Valve style blocks require moving parts; valve-less blocks have no moving parts. In a valve type system a valve of some design is required to shut off the metal flow during the shot cycle and prevent the metal from plugging the vacuum system. These are moving parts that will wear and require routine maintenance prior to, during or after the system’s use. When maintenance will be required is not fully predictable, and component parts must be inventoried to ensure the continued operation of the system. One has only to talk to a current user of valve type blocks to find out they are fairly high maintenance.

The valve-less vacuum system uses no moving parts in the metal flow path, instead it uses resistance to metal flow and the solidification of the metal to shut off the vacuum and metal flow. In addition, the blocks are heat-treated using H-13 material and cooling lines can be incorporated in the block to aid in the solidification of the metal.

• Valve styles use both the metal flow via a secondary valve or electrical switches plus a cylinder to shut off the vacuum with the valve; whereas valve-less styles pull vacuum during the complete shot cycle until the metal solidifies.

Because of their complexity, experience has shown a great deal of downtime associated with these systems, which further adds to the overall cost of the vacuum and prevents many die casters from adopting vacuum assistance as a way to improve casting quality. The simplicity of the valve-less vacuum technology is changing that mindset.

• Those moving components in a valve style block must be maintained and replaced on a routine basis; valve-less style blocks require no maintenance.

Many moving parts can make a valve style vacuum system costly to purchase and maintain. Whether limit switches, timers and/or plc is used to control the vacuum valve open-close, they are expensive to install and maintain, and are subject to failure. The more complicated the system the more likely the system will not perform in a die casting environment. Take, for example, the filters used on most systems. Filters are required to prevent the flow of gases, residue and metal from damaging the vacuum pump, secondary valves and gauges. If routine maintenance is not performed on a regular basis, in many cases the filters plug up, reducing the effectiveness of the vacuum system. A filter is available that is free flowing and does not require the amount of maintenance required in the conventional type.

Here, die cast dies are shown with valve-less vacuum blocks installed. These standardized blocks work for aluminum, zinc and magnesium casting projects.

The valve-less vacuum blocks are designated by size, which relates to the area available to pull the necessary evacuation. The user must determine the size vacuum area required prior to ordering the specific model of block. The calculations for determining the block size are provided by the supplier or there are computer software products available that can provide this data. Generally, the formula for determining the necessary area computes the total volume of the metal feed system—including part and fill time. There are safety factors built into the formula to ensure that the area is adequate to accomplish the evacuation of the cavity.

Valve-less vacuum blocks can be used in aluminum, zinc and magnesium die casting, and many have lasted more than 100,000 shots without repair. Complete systems including tank, pump, controls, filter and gauges are available as is design assistance.

Standardization Saves Money
Vent and vacuum technology has been around since the 1950s. Even valve-less vacuum systems are not new to die casting, but the systems had to be custom manufactured for each project. Only in 1995 did valve-less vacuum and vent blocks begin to become truly standardized. Now complete systems are available off-the-shelf, and the benefits are clear. In most cases, these standardized systems are four to five times less expensive than custom varieties, and add to that a significant savings in valuable production time.

With customer quality expectations running high, and costing pressures like never before, now more than ever die casters can benefit from evaluating these technological advances. Vacuum technology, properly applied, dramatically increases productivity and decreases scrap.

Selecting a Carbide End Mill for Aluminum Applications

noreply@blogger.com (alit76) — Thu, 30 Aug 2007 15:12:00 +0000

Mold shops are currently seeing an increase in jobs where customers specify aluminum instead of traditional mold steels like P-20 and H13. Aluminum alloys offer many advantages for molding, such as good thermal conductivity, lightweight with high strength-to-weight ratio, and excellent machinabilty. For this article we will focus on machinability.

By using carbide end mills with the correct cutting geometries and coatings, metal removal rates can increase by four to five times—or higher—than that of mold steel. Surface finishes of 16µ or better are also easily achieved, reducing mold finishing time considerably.

The results are not quite as strong with long-edge indexable end mills, which will always leave a slight mismatch line between insert rows. Insert pockets are machined into indexable cutter bodies one at a time. Helical cutting edges on a solid carbide end mill are ground in a continuous grinding operation.

Requirements for Efficient Machining of Aluminum
Due to the soft and “sticky” nature of aluminum, specific geometries and characteristics of a carbide end mill are required for efficient machining. Many cutting tool manufacturers offer end mills specifically designed for aluminum for this reason.

A sharp edge and high rake angles are needed to separate a chip from the parent material. Positive rake angles up to 25 degrees radial and 20 degrees axial are common.

A high helix angle, generally around 45 degrees is also desirable. The helix helps move chips up and out of the cutting zone and also generates an excellent surface finish. The angle also helps soften the impact at entrance of cut, resulting in a smoother, quieter cut (see Figure 1).

For aluminum milling a two- or three-flute end mill works best because this allows for larger flute areas. A core diameter of slightly less than 50 percent of cutter diameter is optimum for the same reason. An open flute design is essential for easy chip movement away from the cutting zone. Surface finish on the flute is also critical. Long-chipping, low silicon aluminum alloys have a tendency to stick to cutting tools. As a heated chip flows over the flute it will try to adhere to the tool surface. The flute surface must be very smooth to counteract this tendency.

Extremely slick commercial tool coatings are also available that reduce the friction coefficient on the flute surface. A good example is one that has a friction coefficient of 0.1, less than half that of TiCN.

Figure 1. Key end mill geometries. Figures courtesy of Guhring.

Coolant is important for chip evacuation and keeping the tool cool. Common choices include using an air gun with mist coolant, or flood coolant. Flood coolant with high enough pressure to move chips out of the way is preferable especially if using an uncoated tool. When using a coated tool the air gun with mist coolant is often all that is needed.

When chip management becomes a problem consider using a coolant-through end mill. Coolant ducts exit in the flute area and help move chips out of the cutting zone. Roughing tooth profiles are also helpful in reducing the size of the chip, making it easier to manage and blow out of the way.

All of these elements help reduce the probability of built up edge (BUE), a common failure mode when a general-purpose end mill is used in aluminum machining. BUE is the accumulation of workpiece material on the cutting edge. Once this occurs the cutting action becomes a tearing action. Surface finish drops immediately and spindle load will increase dramatically. If you are cutting a full width slot, tool breakage is most likely to happen before you can get to the feed hold control (see Figure 2).

Whenever possible try to avoid using a dead sharp corner. Sharp corners tend to break down quickly. Using a corner radius or chamfer type end mill will increase tool life.

Putting It into Practice
Now we are ready to machine a mold plate and really make time. If you are to take maximum advantage of high-speed machining of aluminum it is important to have the right machine for the job. Your machining center ideally will have spindle capabilities up to 18,000 rpm and feedrates of 200 ipm.

Figure 2. The result of a poor end mill choice for an aluminum application. The tight flutes and low rake angles of this end mill do not allow good chip flow, and the aluminum chips quickly packed into the flutes of the mill. Not only is the tool destroyed, but the workpiece surface as well.

For peripheral rough milling, the following feeds and speeds will work well as a starting point. For aluminum alloy (2024, 7075, 6061, etc.) try the following: climb mill with a ½" diameter three-flute coated carbide end mill for aluminum. Take a width-of-cut (WOC) of 30 percent of cutter diameter or 0.150", axial depth-of-cut .750", sfm 2,000, rpm 15,280, ipt 0.004, ipm 200 (This value adjusted for radial chip thinning.). Machining at these parameters will result in a metal removal rate of 22.5 cubic inches/minute, impressive for a ½" diameter end mill.

For full width slotting a two-flute end mill is recommended. You can plunge in Z up to 1 x diameter before moving in X-Y or better yet try ramping into the desired depth. Run at sfm 1,000, rpm 7,640, ipt .003, ipm 46. The metal removal rate will be 11.5 cubic inches/minute, half of the peripheral milling example above. However, once the slot is in be sure to program feeds and speeds for peripheral milling again to open up the cavity.

Three Key Points
Choosing and applying the correct carbide end mill will result in substantial time savings for your shop. Three key things to remember are:

Use an end mill specifically designed for aluminum machining.
Use a machine with high speed and feed capabilities.
Be sure to evacuate chips from the cutting zone.

Chances are your competitors are using these techniques, you can too.

Solutions for Your Large Mold Machining Challenges

noreply@blogger.com (alit76) — Thu, 30 Aug 2007 13:13:00 +0000

The demand for large, highly cosmetic molds is growing rapidly. From flat-screen TVs to automobile dashboards, designers are pushing the size and complexity of molds. Given this fact, large mold manufacturing is an area where many shops are finding opportunity to compete globally.

So why isn’t everyone producing large molds? There are many barriers to entry, the most significant of which is the assumption that large molds are very difficult to machine. Old technology leads to long cycle times, slow feedrates, many setups and hours of hand polishing. However, high-performance machining technology can make large mold machining more like small mold machining.

Large Molds Have Issues
Dealing with the sheer size and weight of a large mold can be a big challenge. This often leads to excessive labor, the need for special equipment, multiple setups and potential inaccuracies.

If the proper machining center is chosen for the manufacture of large molds, many of these problems can be reduced or eliminated, easing setup, change-over and other potential accuracy issues.

The biggest expense often associated with the manufacture of large molds is machinery cost. Machines capable of producing big molds are expensive, so having multiple machines, one for roughing and another for finishing, for example, is a large barrier to entry for this market. When the proper machine is chosen, it is capable of roughing and finishing, even in the same setup and without losing accuracy.

Machine Designs for Large Molds
To counter common accuracy and setup concerns in large machines, we must look at some of the necessary design characteristics of a large mold machining center.

Cast Iron Construction and Spindle Capable of Dealing with Heat
The first thing any machine designed to mill large parts needs is a massive, cast iron construction and a spindle capable of dealing with heat. Cast iron is still the most stable material for machine construction, adding rigidity and heat-sink characteristics to the machine.

As far as the spindle is concerned, it must have internal technology built to cool the spindle from the bearings out, ensuring that the spindle is not going to burn itself out or lose accuracy with thermal expansion.

These items are important because large molds spend much longer in the cut than smaller ones, adding to the concerns of stress on the mold and heat. Without a well-built foundation, no machine tool will produce quality large molds due to these two factors. Vibration must be limited and heat must be dealt with.

To achieve the highest possible surface quality in large molds you will need a machine and tooling up to the task, allowing you to dramatically reduce secondary EDM work and manual finishing time. Images courtesy of Makino.

Most large molds will be machined for days, meaning outside conditions will change as the part is machined, and those changes must be taken into account to achieve the necessary accuracies. In a machine not designed for the cutting conditions of a large mold, a 10oC environment temperature change results in a six-degree machine column temperature change, causing a spindle-angle plate parallelism change of 0.070mm.

Thermal Stabilization Technology
On the other hand, with a machine utilizing thermal stabilization technology, the same environment change results in a three-degree column temperature change, or a 0.030mm spindle-angle plate parallelism change. Therefore, machine design must also be conscious of environmental thermal effects, shielding outside air influences from affecting the part. If the machine you choose is thermally stable, it will also reduce blend-line problems; and, therefore reduce the need to hand polish the part.

Speed
A second machine feature to consider is speed. The spindle should run at least 20,000 rpm and metal removal rates should be at least 30 ipm. For example, there is a large mold machining center with rapid traverse and cutting feedrates of 787 ipm.

Accuracy
Accuracy is important in large molds if you plan to finish and rough on the same machine. The machining center you choose should be capable of similar positioning accuracies and repeatability of smaller machines.

Use a large mold machining center with a positioning accuracy of ±0.000060 inches (±0.0015 mm) and repeatability of ± 0.000040 inches (±0.001 mm). Also keep in mind that pitch accuracy is important, and should be kept within about 5 microns.

Feedback Resolution
To measure just how accurate you are machining, you must be aware of the machine’s feedback resolution. With a standard one micron feedback resolution, imperfections are common. When you get down to a 0.050 micron feedback resolution, the finish is nearly flawless. Control resolution, scale feedback and fine pitch ball screws all allow for this improved surface finish.

Spindle
Another machine design consideration is the spindle. The spindle on a large mold machine should be capable of predictable roughing, semi-finishing and high-quality finishing. As a benchmark, surface finishes should be able to get to around 2 microns. Tight finishing characteristics are especially important in shut-off and parting lines, where many moldmakers are forced to hand polish to make up for the inaccuracies of their tools. Also, because large machines are much more expensive, buying multiple machines for these three tasks is impractical.

A variable geometry horizontal machine designed for 2+3 machining of large, complex molds. It has superb accuracy and the ability to achieve bench-free surface finishes.

In addition, the spindle must be designed to maximize tool life over extended machining periods by providing minimal vibration and growth. For example, when running a large fascia mold on a large mold machining center, you are able to obtain more than 30 hours of life with a 16mm CBN insert finish tool running at 314 ipm and achieving a surface finish of 0.336 micron Ra, 3.02 micron Rmax. Tooling costs add up quickly when machining a large mold, and having a machine designed to maximize tool life can save thousands of dollars per mold in tooling costs.

Movable, Multi-Axis Head
A desirable feature for the machining of especially complex large molds is a movable, multi-axis head. A variable geometry head design allows for simultaneous three-axis machining, capable of milling deep mold cavities and cooling holes, as well as many other cut combinations in the same setup. Because the size and weight of the workpiece translates into long setup times, reducing setups with three-axis capabilities without losing accuracy can go a long way to improving the ability for a shop to machine large molds. In addition, a multi-axis head will allow for slanted-hole machining, accomplished by tilting the spindle at an optimum angle for improved access to the milling point.

A multi-axis head also allows for the use of shorter tools. A shorter tool is always a more rigid, accurate tool, and prevents the spindle and the tool from colliding with the table. Finally, a multi-axis head allows for improved surface finish by using the radius edge instead of the tip of the tool.

Chip Management
Chip management becomes a serious issue of concern with large molds. On some large mold machining centers eighteen outlet holes are provided below the table of the machine to reliably catch chips, regardless of the table position. Four built-in hinge-type chip conveyors evacuate chips at high speed toward the front of the machine. The bed and column are protected by covers to prevent any freshly cut hot chips and coolant from direct contact with the machine’s cast-iron surfaces. The areas around the column and the bed as well as underneath the bed are insulated to eliminate thermal changes in the cast-iron machine structure caused by variation in the shop temperature.

Without an effective chip management system, no large mold machine will be able to operate without break-downs or thermal issues.

High Pressure Coolant Capabilities
A final feature that is important when choosing a large mold machine is high pressure coolant capabilities. For example, when drilling angled holes with a 2+3 machining approach, 1000psi coolant will allow for effective chip evacuation and more accurate cuts. Without the high pressure coolant, the tool will often block the chips from leaving the hole, causing chips to be re-cut. Having the ability to effectively machine angled holes will eliminate setup time and additional machinery needed for gun drilling, as is typically done for these types of cuts.

Large Mold Examples

Circle, Diamond and Square

Purpose of the detail is to the show the machine cutting simplified geometry in multiple locations. The parts are then measured to highlight the machine construction which allows accuracy to be performed in many locations.

• Toolpathing was kept to a simplified circle routine (G02 and G03) common in all machine controls. This allows the machine to perform to its core of accuracy without any influences from programming software.

This also showcases the machine ability to cut accurately using multiple feedrates.

• Typically machines were limited to one feedrate that would cut to accuracy.

• Backlash and compensation were all set to maximize one feedrate, typically the feedrate that would be used the most. As one can imagine if another feedrate was utilized inaccuracy would quickly appear.

Angled Drilling Holes Sample

Purpose of this detail is to the showcase the 2+3 stiffness as it relates to drilling large holes.

• A standard, off the shelf high speed steel drill was used to produce the hole in the material. Typically customers will not want to spend the difference in dollars when it comes to buying large carbide drills. Carbide drills in this size are expensive.

• High-speed drills don’t perform to the level of carbide but are common in many shops. This head was able to produce a hole using standard approaches with large drills.

IP/Fascia Sample

This detail was provided as a test of the machining ability of a large mold machining center. The purpose of the test is to machine a large IP/fascia in one setup using all the capabilities of the head to tilt and tip while still being able to rough the block from solid. One setup, one machine.

• Typically a part of this size would be roughed, semi-finished and finished as much as possible in a three-axis machine. A multi-axis machine would be used to do areas that tooling length could be reduced by tipping the tool. The reason for not doing all the work in the multi-axis machine is because of rigidity of construction and the inability of this machine to rough. Simply, some multi-axis machines are capable of finishing only.

• The determining factors for removing the detail and placing it on a multi axis machine will vary from part to part. However one reason seems to be constant in all cases. The geometry gets to smaller diameters where the combination of higher spindle speeds and shorter tooling need to be used.

The detail would be removed from one machine and placed onto a multi-axis machine to finish difficult areas.
This would account for only about 5 to 10 percent of the total machining time.
Part processing time goes up significantly once this part is removed from a three-axis machine to a multi-axis machine.

Conclusion
The technology exists to successfully tackle the large molds of today and tomorrow, as long as you keep in mind the problems associated with large mold machining and the machine design features that counter those issues, large molds can be machined much like small molds.

Plastic: Is it the new black gold?

noreply@blogger.com (alit76) — Thu, 23 Aug 2007 05:22:00 +0000

According to the report from the Ministry of environment, Mauritius produces some 120 tons of plastic wastes daily amounting to a total of 43,800 tons of waste every year of which only 4%, representing some 164 tons, are recycled. In 2006, the population’s consumption of non-biodegradable plastic products amounted to some 70 million Polyethylene Terephthalate (PET) bottles, 7 million PVC bottles, and 113 million plastic bags.

Now just imagine a process able to clear our environment of plastic wastes, creating jobs in waste management and collection and at the same time bringing useful resources such as petrol and gas, which can be beneficial to our economy. The Liquid Hydrocarbons pilot project proposed by the Green Hydrocarbons (Mtius) Ltd has the ambitious desire of turning our plastic wastes into hydrocarbon petrol.

The environment friendly project, realized with the collaboration of the initiators of the project in India, Unique Waste Plastic Management & Research CO. Pvt. Ltd., will enable Mauritius to get rid of its plastic wastes while at the same time providing resources such as petrol. The initiator of the project will bring all the technology and equipment necessary for the setting of the pilot plant while the government, in collaboration with Green Hydrocarbons Ltd., will provide the necessary location and licenses.

The ratio of the conversion of the plastic waste into petrol is one kilogram of plastic into the volume of 1000 cc of petrol. The pilot project will hence be converting some 2.5 tons of plastic wastes daily into some 25,000 liters of petrol and other by-products. This project is a green alternative to the palliative solutions that have been found so far to deal with plastic wastes. Land filling, incineration, recycling, gasification and blast furnace have shown their limits in the treatment of plastic wastes.

Recycling is unfortunately not a practical solution in that the cost of collection is quite high; there is a limited market for it, with an absence of marketing. Moreover, plastic can only be recycled three to four times, after that it loses its strength and can’t be recycled. The project realized with the collaboration of Indian partners is due to start in the course of the year 2007, once the EIA obtained.

Beginnings

The concepts of plastic conversion into hydrocarbons was elaborated by Professor Alka Zadgaonkar of the Raisoni College of Engineering, Nagpur in Indian, in the year 1995. While giving a lecture on Applied Chemistry, she came up with the idea of turning plastic back into hydrocarbons. She worked with a team on the formula and in 2004; they succeeded in turning 300mg of plastic into hydrocarbon liquids.

Unique Waste Plastic Management & Research Co. Pvt. Ltd of India later launched a pilot project where some 5,000 tons of plastic wastes were converted everyday. The process was later extended to treat 25,000 tons daily in 2006 and the objective of the project is to treat some 450,000 tons. She asked for analysis by Indian Oil and made a number of recommendations for the use of the final products.

After about one year of operation, the project was realized with the help of loans. Representatives of the State Bank of India acknowledged that the project is already running on profit, thus proving the efficiency of the method. The world produces no less than 60% more plastic wastes than it did some ten years back with a production of 100 million tons every year. India produces 10,000 tons of plastic wastes everyday which 40% are recycled.

This project has enabled India to better manage the country’s plastic wastes while at the same time creating jobs. Actually India sells its hydrocarbon at 40% to 50% less than normal diesel. The technology is presently being exported to other regions such as Rajasthan and even to America; for instance, some hospitals are being operated using their own wastes.

The investments for the pilot project in Mauritius are estimated to around 100 to 300 millions Rupees. Land filling, incineration and recycling 4% are presently being used but they do not resolve the problem of environmental damage caused by plastic. The Waste to Compost project, will however give a new dimension to the processing of plastic in that hydrocarbon and the other by-products used as compost.

Sheet Metal Fabrication Processes Overview

noreply@blogger.com (alit76) — Thu, 23 Aug 2007 05:19:00 +0000

Sheet metal fabrication involves many different processes and methods. Each method works in a different way to produce different end results. Sometimes two process will create the same result through different methods. Sheet metal fabrication methods all work to do the same basic thing - shape and design sheet metal into a final, useable product. The following list explains some different methods of sheet metal fabrication:

- Annealing is a process of sheet metal fabrication that softens the metal through heat and cold.

- Bending is the process that uses strain to either cut of bend the sheet metal.

- Cold forming is the term used to describe any sheet metal process that occurs at room temperature. These processes are done to increase the hardness and strength of the sheet metal.

- Cold rolling is a process where the sheet metal is rolled through rollers and compressed to establish hardness.

- Drawing is the process where metal is punched to form cylindrical shapes. It stretched the metal and forms a permanent shape.

- Forging is shaping sheet metal by hammering or pressing.

- Hot forming involves all processes that use heat. These process melt the metal and allow it to be easily shaped or stretched.

- Piercing is the process of punching holes into the sheet metal.

- Press forming is any process that uses a hydraulic press to shape the metal.

- Roll forming is the process of shaping sheet metal into long parts by running it through rollers.

- Welding is when a tool is use to heat up the metal and bond two or more pieces together.

About the author: Courtesy Manufacturing Company is a precision metal component manufacturing facility that specializes in precision metal stamping, metal fabrication, and assembly.

Understanding Sheet Metal Fabrication and How It Works

noreply@blogger.com (alit76) — Thu, 23 Aug 2007 05:18:00 +0000

Sheet metal fabrication is the manipulation of metal to create any type of component that will be used in an end product. It can be used in almost any manufacturing field including medical, computer, electronics, or appliances.

Any product that contains metal components will go through some form of sheet metal fabrication.

In sheet metal fabrication, several processes are used to reach an end product. These include cutting, forming, and finishing.

Aluminum, stainless steel, and others forms of metal are utilized to create a component for a larger piece, something that can be used to create an end product, or the end product itself.

The Cutting Process
Sheet metal cutting involves a number of ways to cut a piece of metal into smaller pieces. These small pieces of metal can then be molded or formed into a final piece. One form of cutting is called shearing, which is used to cut larger pieces into smaller ones using the process of shear stress on a cutting machine.

Another process is called Electrical Discharge Machining, or EDM, in which conductive materials are melted with an electrode spark from a thin, charged electrode that is surrounded by iodized water.

In abrasive cutting, grinders or saws are used to cut through sheet metal.

Sometimes water jets are used. These generate no heat while cutting, but instead use high pressure water from 20,000 to 60,000 psi. There is also laser cutting where lasers are used for complex, or precise, cutting.

The Forming Process

Once the sheet metal has been cut, it will be formed into its required shape to create a component before finishing. There are several forming techniques. Rolling is used to shape flat pieces of metal over and over by the use of roll stands. In bending and forming, the sheet metal is manipulated basically by hand to form a desired shape.

Stamping involves tools and dies that are used to stamp designs into the metal. The designs might also be 3-D designs. A method called punching is used to punch holes in the metal. Welding is used to join pieces of sheet metal together by forming a bond between the metals. To add latches or handles to the sheet metal, hardware and fastener creation methods are used.

The Finishing Process

After cutting the sheet metal and then forming it into the shapes needed, it must go through a finishing process. In finishing, the sheet metal is sharpened to eliminate or polish rough spots and edges using an abrasive.

After the finishing process, the sheet metal goes on to fulfill its next purpose. It is either shipped out as an end product, or if it is a smaller piece, it might be used on a larger component or product.

Saving Money on Sheet Metal Fabrication

There are companies today that specialize in the sheet metal fabrication business. Their customers are usually companies that sell or use an end product that is made of sheet metal, or a part of it is made of metal.

Instead of opening a factory to create their own metal products, a company might hire a sheet metal fabrication specialist to do the work for them.

This gives the company more time to focus on marketing and promotion and can also save money.

About the Author: Courtesy Manufacturing Company is a precision metal component manufacturing facility that specializes in precision metal stamping, fabrication, and sheet metal assembly.

Graphite and It's Effects on the Human Body and Toolroom Equipment

noreply@blogger.com (alit76) — Thu, 23 Aug 2007 05:16:00 +0000

The health and welfare of toolmakers that use graphite to make electrodes for use in the EDM department should be a high priority for management. In addition to the health issues for the workers, the very expensive machinery, such as the EDM machines and milling machines, must be protected from the damaging effects of graphite dust.

Anyone who has worked with graphite in the manufacturing of EDM electrodes is keenly aware of the need for proper dust removal during the machining process. Many ill-equipped shops have very little equipment to handle the dust generated during milling and grinding operations.

Safety

The MSDS (material safety data sheet) for the synthetic graphite used in EDM show that there are no carcinogenic properties associated with graphite. It is a chemically inert material and contains no volatile components. It is also used for medical purposes, such as implants and heart valves in the human body.

This is not to say that graphite is totally harmless though. It can be very irritating to the skin, eyes, and nasal passages. It can cause stinging, redness and watering of the eyes, and itching of the skin. This can be a very annoying experience when a toolmaker is expected to produce a close-tolerance electrode with a fine finish.

Controlling the Dust

The simple but very ineffective solution is to wear particle masks. Experience shows that this stop-gap measure is a failure. The mask soon is clogged with the fine dust and the operator is left breathing a disgusting blend of bad-breath and graphite dust!

Portable vacuums are the next best solution, but this also has many drawbacks. Often the filter in the portable shop vacuum is not fine enough to trap the microscopic sized particles, and they are simply blown back into the air. Also, because the vacuum hose is often cumbersome to manipulate, operators fail to properly align the hose to capture the most dust.

Many shops use a centralized vacuum system designed for the removal of fine dust particles, such as graphite. It is important to have enough air velocity in the vacuum system to be effective. It is recommended to have an air velocity of 500 ft. per minute and the air in the lines should travel at a rate of 2,000 ft. per minute in order to prevent the dust from settling inside the duct work.

With a centralized system it is much easier to efficiently manage the dust from the various machine tools because the system is more efficient and the hoses can be strategically placed. Special wheel guards are available for surface grinders that act as a turbo to remove the dust into the vacuum system.

Newer milling machines which are more or less dedicated to electrode machining are equipped with extremely effective dust removal systems. The sealed chamber around the work area enables the vacuum to capture a high percentage of the dust. This development has dramatically reduced the amount of graphite dust in the shop environment.

An additional method of dust removal is the use of a curtain of coolant surrounding the milling cutter. This prevents the dust from ever escaping and is very efficient. This feature is available on some milling machines as well as an accessory that is easily installed.

A Clean Shop Environment

Graphite dust is highly conductive and has been responsible for the damage of many expensive tools and machines. Glass scales can give false measurements due to the settling of dust. Electronic equipment can be short-circuited by the dust as well. The grimy nature of graphite makes it especially annoying if it accumulates on work-benches and desks.

It is in the best interest of everyone to make every effort of maintain a clean and pleasant atmosphere in a moldmaking or EDM shop. The toolmakers will be happier, the work will be better and the machinery will perform as it should. It is also very impressive to visitors to see a clean, dust-free shop.

The Life of a Sterling Silver Chain: From Mine Find to Accessory Neccessity

noreply@blogger.com (alit76) — Thu, 23 Aug 2007 05:11:00 +0000

Have you ever thought about the wonderfully shiny sterling silver piece that adorns your neck, ears, or wrists? What it is, where it’s from, and how it got here? Silver is ubiquitous in the jewelry industry, and widely used in many others, but there is a certain disconnection between the mines where metallic ore containing silver is excavated, and the world of high fashion where silver has reigned for millennia. If you love metal accessories as much as we do, you might enjoy a brief walk through all the hard work that goes into turning raw silver into a beautiful chain, and an understanding of why silver and gold chains are as expensive as they are. You just might come out of it with an even greater love and respect for your favourite silver jewelry!

Mining

Before anything, a site is chosen that has indicated high levels of natural metal deposits in the Earth. Once a candidate has been decided upon, the site is scrutinized by environmental specialists and mining engineers in a series of studies, tests, and calculations. Since there are rigorous government controls on mining, the very confirmation of a piece of land as the future site of a mine can be a 2-5 year process. The mining company is also obligated to ensure, before any construction begins, that after the site has been depleted of valuable minerals there will be an environmental rehabilitation process to restore the land. Huge amounts of expertise and critical thinking go into making mining projects safe, environmentally sound, and effective- before they’ve even started construction! There are generally two types of mines: surface level mines, which surround their site like an enormous football stadium, and underground mines, which can be located deeper than a mile underground, where they carve out a virtual subterranean society. Either way, the scale is huge and the technical coordination is astounding.

Silver, like all metals, is found as a mineral encrusted below the earth’s surface. What many may not realize is that silver, copper, lead, and gold are most frequently mined in the same place and found in the same ores, and separated afterward. Only about a quarter of all silver produced is mined from ores that are specifically harvested for silver. Even from those rare ores predominantly made of crude silver, trace amounts of copper, lead, and gold will be recovered and saved, just as trace amounts of silver are recovered from lead, zinc, and copper ores.

Refinement

Once the ores are recovered from the earth through painstaking physical labour and specialized mechanical machinery, they are shipped from the mine to a reduction plant to be milled. Reduction plants (also called ‘mills’) are usually located adjacent to or nearby the mine itself, established alongside the realization that the site will be profitable for years to come.

At the mill, the ores are ground into powder into giant drums to increase surface area, quickening the effect of metallurgical chemicals. Various metallurgical extraction processes are employed to isolate the desirable elements, ridding the original ore of unwanted impurities like antimony, arsenic, and tin, and separating usable metals like copper, lead, zinc. After all chemical treatments, intense heating, and physical separation, silver can emerge as pure as 95%.

At that point, it is shipped to a precious metals refinery. There the silver is soaked in nitric acid, dissolving into the mixture. Silver precipitant crystals are added to the solution, and the acid is drained and neutralized. The result is pure silver in the 99th percentile!

Alloys and Wire

Pure silver that will be used in the jewelry industry then typically gets shipped to a wire factory. There it can be alloyed with other metal to produce sterling silver, also known as standard silver, which is 92.5% silver (the remainder typically composed of copper). Sometimes sterling silver is also referred to as 0.925 silver. The alloy is heated yet again to become soft, and drawn through specially cut dies to be formed into wire. Depending on the width of the die, different gauges of wire are created.

Chains

Spools of sterling silver are shipped to chain makers, which range from small studios to fairly sizeable factories. This is perhaps where the silver industry ends and the jewelry industry begins. Automated machines are used to produce chains of almost countless different styles. Cable chains, snake chains, satellite chains, ball chains, figure eight chains, rolo chains, square chains… the list goes on. For each different style of chain link, a different specialized machine is required. Generally, the wire is fed into one side of the machine, where, depending on the style, it is bent, flattened, curved, soldered, and moved along. The following link receives the same treatment, and is joined to the first one. For simple chains this process continues until a long sequence of identical links emerges at the other side of the chain machine. Some chains are not so simple, and may involve 2 or more different kinds of links. Because most machines can only produce one size of one style of link, they must either be recalibrated to produce new effects and sizes, or, more likely, multiple machines must be used in combination.

Since there are so many different styles of chains, and a dedicated machine for each, there is indeed a smorgasbord of different chain making machines. Larger operations have upwards of 600! Other chains may feature indents, hammering, brushing and other personal flourishes that are achieved by hand, adding a human touch at the cost of skilled and time-consuming labour.

Chains that have completed the shaping process often undergo an additional electroplating process. This is where a very thin layer of an even more precious metal like gold or rhodium are plated onto the sterling silver through an electrochemical process that achieves a nearly flawless coating all over the chain. Plating is done with a number of benefits in mind, and is frequently used to change the colour, reduce the possibility of tarnishing, or increase the hardness.

And voila! The chain is born! A quick recap: silver-containing ores are mined from sites that are cultivated with the utmost of technical skill and environmental care, shipped to the reduction plant and broken down into constituent parts, shipped again to refineries that produce pure silver, shipped yet again to wire factories, and then shipped again as pure or alloyed wire to chain makers, where the chains are crafted and electroplating occurs. After that, the finished chain is, you guessed it, shipped all over the world, where jewelry enthusiasts incorporate them into original designs. The whole multi-stage process requires technical planning, environmental care, chemical engineering, huge machines, hard work, creativity, and a lot of transportation.

Silver in the World Today

The world’s most prolific silver-producing nations are Peru, Mexico, and Australia, but the most skilled and effective chain producer is Italy, where artisans have long cultivated silver working techniques and slowly amassed a virtually incomparable variety of machines. Furthermore, chain links are patented by the companies that build the chain making machines, so classic Italian designs are not commonly available outside the country. All of this means that if topnotch chains are sought after, intercontinental transit is involved, and Canadians have to buy most of their jewelry silver at a disadvantageous exchange rate. While the Canadian dollar has been remarkably successful lately, especially against the American dollar, the Euro has been quite strong. As the price of raw silver has doubled in the past 5 years, and the whole process of transforming it from an unrefined mineral to a finished jewelry chain is so extensive, there is also a great deal of economic strategy in keeping the costs as low as possible at every stage.

A quick note on silver economics: as of May 1st, 2007, the price of pure silver was $0.47 CAD/gram. After being shipped, made into wire, shipped again, made into chain, shipped internationally to the supplier (with duties applied), and marked up every step of the way, it will end up costing the consumer upwards of a dollar per gram. Not bad, really, considering all of the shipping and markups. If you find silver chains for $0.60/gram, there are generally two possibilities: either the supplier bought it when it was worth much less, or it’s not pure silver. It could be a lower grade alloy or silver plated.

Treasure the beautiful silver chains that flow into your country and around your limbs, and do not take them for granted! They are the result of skill, creativity, time, and hard work. Given everything that went into them, it is no wonder that sterling silver necklace you own is so valuable! And with recent stock market increases, your favourite silver bracelet that you bought 5 years ago is now worth twice as much. In financial terms, that’s a pretty good return on investment indeed.

Anatomy Of Free Machining Steel

noreply@blogger.com (alit76) — Mon, 20 Aug 2007 10:13:00 +0000

In The Cut

There’s a lot of action in the cutting zone. Plastic deformation of the parent material allows a chip to shear in the primary shear zone. Friction created in the three main shear zones contributes to premature tool failure. Lubrication from machinability additives in the steel and external application of cutting fluids help reduce the effects of high temperatures.

The intersection of a cutting tool and workpiece material is a violent and very hot place. A cutting tool is designed to attack a material in a way that lifts a chip. The energy that is put into the cutter, feed and speed is output in the form of heat. The more energy that is put into the cut, the more heat is produced.

Chips are actually cut from the material slightly ahead of the tool. This area is referred to as the primary shear zone. It's where the pressure and forces are sufficient to create plastic deformation, which allows the material to yield to the cutter.

Also in the cut, a secondary shear zone forms along the face of the cutting tool. This is where the chip actually slides up the face of the cutter. The friction in this area of the cut can raise temperatures to 1,2000 C.

Finally, there is a third shear zone that is located under and slightly behind the leading edge of the cutter. This zone is formed by springback material at the bottom of the cut that was depressed as the primary shear zone yielded.

Because steel is produced as a liquid and because there are numerous elements suspended in that fluid, how they are distributed in the solid material you're cutting affects how smoothly and consistently this chip formation process occurs. Think, for example, if the cutter is merrily traversing a workpiece and hits an inclusion of very hard carbide, the yield of the material will change dramatically. It could possibly break the edge off the tool. For steelmakers, achieving heat-to-heat consistency, which reduces "surprises" in the cut, is the ongoing technological challenge.

CAM Software Turns Operators Into Engineers

noreply@blogger.com (alit76) — Mon, 20 Aug 2007 09:49:00 +0000

Like many other United Kingdom subcontracting companies, Jetblades Engineering (Coventry, England) has had to change its operating methods to cope with the new manufacturing environment. Managing Director Mark Kirby relies more than ever on the company’s PowerMill CAM software from Delcam Inc. (Windsor, Ontario, Canada) as he moves the firm from production machining to short-run manufacturing. At the same time, he is increasing the skills of his staff, effectively turning his machine operators into more broadly skilled engineers.

“We have to face the reality that most long production runs are going to be moved to countries with lower labor costs,” Mr. Kirby explains. “However, there is still plenty of demand for short runs of prototypes and one-off components. The problem is that we used to be able to amortise the setup costs over the production run. We need to persuade our customers that these costs will be proportionately higher now because they are concentrated on a few parts or even on a single item.”

Jetblades produces between 100 and 200 different components each year. Many of these are complex parts, often needing more than 100 tool paths to manufacture them. Therefore, a broader set of skills is needed for this type of work.

One significant change for the company has been a move into five-axis machining with a Variaxis 630 machining center from Mazak Corp. (Florence, Kentucky). “The machine is especially useful for aerospace and other demanding applications, since most projects can be completed in one or two setups,” Mr. Kirby says. “The reduction in setups saves time, but most importantly, the accuracy is increased. It is virtually impossible to keep to tolerances of less than 10 microns, which we often need, over a long series of different setups,” Mr. Kirby says.

Jetblades Engineering’s machine operators have learned to use this CAM software and, as a result, have helped the company understand its customers’ needs more than ever before.

“Machining times have also been driven down by developments in cutting tool technology, which has moved foward tremendously in the last 5 years,” Mr. Kirby adds. “We are now able to use speeds and feeds that would have been suicidal in the past. Our PowerMill software has kept up with these developments and allows us to get the most out of our machines.”

Now the majority of the time for any given job goes into planning the most efficient sequence of operations and working out how to hold the part at each stage. “As far as training the machine operators to use the software so that they can develop their own programs, I have moved the CAD/CAM office next to the shop floor so they can still see and hear the machines working,” Mr. Kirby explains.

The move to making a smaller number of parts means that every piece is more critical. Getting the process right the first time used to be desirable, and now it is essential. Mr. Kirby says, “You cannot lose the cost of a few defects over a long production run anymore, so reliable software is more important than ever. The simulations we get from ViewMill are an essential aid to planning for successful machining.” ViewMill is an option in PowerMill that includes enhancements such as the shading of each tool path in a different color for easy identification.

“The advantages of PowerMill are the ways in which you can refine the programs to make the process more efficient and the quality you get in the finished components,” he continues.

Jetblades also uses the software to capture its manufacturing knowledge. For example, automotive aftermarket and limited production run projects often require a series of iterations on a single part. The shop can save time by recording a session file in PowerMill for the first example. The same tooling and strategies can then be applied to each revised design.

The shop produces between 100 and 200 different components each year, many of which are complex parts often needing more than 100 tool paths to manufacture them.

“The regular seminars and user meetings held by Delcam are an important part of our training process,” Mr. Kirby adds. “In addition, the support has always been excellent. We pay a significant amount in maintenance, and we certainly make sure we get value for our money.”

Despite the many challenges, Mr. Kirby is confident of success with his new approach. “Designers still don’t understand manufacturing well enough, and the situation is becoming worse as OEM companies subcontract more and more of their production,” he explains. “The local suppliers’ main advantage is the ability to talk to the designer and discuss things face to face.”

One common problem with designers is that they often add cost without adding value, according to Mr. Kirby. Designers regularly set a tolerance based on what they believe is possible rather than on the real requirements of the specific part. A good local subcontractor can often save his customer significant amounts of money simply by asking “Did you really mean that?” In contrast, an overseas supplier will usually make whatever is on the drawing, without considering any cost implications, he explains.

With its CAM software now being in-house, Jetblades has an advantage over its competition. Not only can the company work more closely with its customers to customize their needs, but it can also do jobs with even more precision at tight tolerances.