BLOW MOULD

#1 PLASTIC HEAT INPUT

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Extrusion Blow Molding

> Inspect all machine ventilation systems to ensure adequate air flow.

> Check operating manual of the machine for other startup checks and requirements

that have to be met such as motor load (amperage) readings.

Startup

The following startup procedure provides a general review since each line has specific

requirements. When starting up a new extrusion setup, start the screw rotation at

about 5 rpm. Gradually look into the air gap between the feed throat and throat

housing and make sure the screw is turning. Screws have been installed without their

key in place, or the key has fallen out during installation. Also make sure that

antiseize material is applied to the drive hub, to help installation and removal. Also if

the key is left out and the drive quill is turning and the screw is not, the screw will not

gall to the drive quill.

Details for operating the machine are based on what the plastic being processed

requires, such as temperature settings, screw rpm, etc. available from

the material supplier and=or experience. Startup procedures involve certain precautions:

> Starting with the front and rear zones die end and feed section, one should set

heat controllers slightly above the plastic melting point and turn on the heaters.

Heatup should be gradual from the ends to the center of the barrel to prevent

pressure buildup from possible melt degradation.

> Increase all heaters gradually, checking for deviations that might indicate burnedout

or runaway heaters by slightly raising and lowering the controller set point to

check if power goes on and off.

> After the controllers show that all heaters are slightly above the melt point, adjust

to the desired operating temperature based on experience and=or lastic manufacturer’s

recommendation, checking to ensure that any heat increase is gradual,

particularly in the front=crosshead.

> The time required to reach temperature equilibrium may be 30 to 120 min,

depending on the size of the extruder. Overshooting is usually observed with

on=off controllers.

> Hot melts can behave many different ways, so no one should stand in front of the

extruder during startup, and one should never look into the feed hopper because of

the potential for blowback due to previous melt degrading, and so on.

> After set temperatures have been reached, one puts the plastic in the hopper and

starts the screw at a low speed such as 2 to 5 rpm; some plastics, such as nylon,

may require 10 to 20 rpm.

> The processor should observe the amperage required to turn the screw; stop the

screw if the amperage is too high, and wait a few minutes before restart.

> When working with a melt requiring high pressure, the extruder barrel pressure

should not exceed 7MPa (1,000 psi) during the startup period.

#1 TWIN SCREW EXTRUDER

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Although there are fewer twin screw than single screw extruders, they are widely

employed for manufacturing certain products, in particular specialty operations such

as compounding applications. The popular common twin screw extruders (in the

family of multiscrew extruders) include tapered screws with at least one feed port

through a hopper, a discharge port to which a die is attached, and process controls

such as temperature, pressure, screw rotation (rpm), melt output rate, and so forth.

For all types of extruders if the goal is to deliver a high quality melt at the end of the

screw, the plasticating or melting process should be completed prior to reaching the

end of the screws. Twin intermeshing counterrotating screws are principally used for

compounding. Different types have been designed with basically three available

commercially that includes corotating and counterrotating intermeshing twin screws;

nonintermeshing twin screws are offered only with counterrotation. There are fully

intermeshing and partially intermeshing systems and open- and closed-chamber

types. In the past major differences existed between corotating or counterrotating;

today they work equally well in about 70% of compounding applications, leaving

about 30% in which one machine may perform dramatically better than the other.

Figure 3.27 shows the different designs used with the twin screw extruders.

Similar to the single screw extruder, the twin screw extruder, including the multiscrew,

has advantages and disadvantages. The type of design to be used will depend

on performance requirements for a specific material to produce a specific product.

With the multiscrews, very exact metered feeding is necessary for certain materials;

otherwise output performance will vary. With overfeeding, there is a possibility of

overloading the drive or bearings of the machine, particularly with counterrotating

screw designs. For mixing and homogenizing plastics, the absence of pressure flow is

usually a disadvantage. Disadvantages also include their increased initial cost due to

their more complicated construction as well as their maintenance and potential

difficulty in heating

3D AND CONVENSIONAL PRODUCT DESIGN FUNDAMENTALS

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Different techniques are used for placing the monolayer or coextruded plastic parison

into 3D positions such as:

#articulate the extruder nozzle,

# articulate the mold platen,

# robotically orient the parison, and suction blow mould.

Sequential blow mould can be used to integrate hard and soft regions of different plastics on a

single tubular structure (parison). This diagram shows two

extruders controlling the sequence coextrusion of operation. It can use rigid–

soft–rigid, soft–rigid–soft, and so on plastic combinations via accumulators ‘‘1’’ and

‘‘2.’’

In the meantime a certain number of different systems became

established in the market: suction blow mould, 3D blow mould with parison manipulation, and a split

mold, horizontal machine with vertically opening mold and a six-axis-robot laying the

parison into the cavity or a machine without using a closing unit. All these systems

can be combined with six- or seven-layer coextrusion or with sequential coextrusion

running hard–soft–hard plastics one after the other.

If strongly bent, 3D curved products, such as filler pipes for automobiles, are

produced with traditional technology. Flash areas near the mold parting line

cannot be avoided and result in high flash percentages and surrounding pinch lines. In

extreme cases the amount of flash can reach several times the actual article weight.

The very long pinch lines lead to extremely high clamping forces.

With 3D, substantial savings are possible that may be achieved by using BM

machines specifically designed for the production without (or at least with significantly

reduced) pinch line. In these processes the extruded parison (with a diameter

smaller than the article diameter) is deformed and manipulated and then moved

directly into the mold cavity so that the remaining pinch line length is reduced

to a minimum. The 3D manipulation of the parison with programmable manipulators

or six-axis-robots and special devices allows the pinchless production of complex

articles. These advantages require a higher effort as to the machine technology,

depending on the article quality required and therefore also to type of process applied.

General Temperature Processing Guide

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Suggested starting points only

Zone 1 Zone 2 Zone 3 Zone 4 Head (A) Melt Mold

Material temp _F temp _F temp _F temp _F temp _F temp _F temp _F

ABS 380–440 390–440 400–440 400–440 400–440 400–440 110–170

Acrylic 370–460 380–460 390–460 400–460 400–460 400–460 130–200

LDPE 320–340 320–350 330–360 340–370 330–380 340–380 40–100

HDPE 350–390 360–400 370–410 370–420 370–420 370–420 40–100

Nylon 6 440–480 450–480 460–480 470–490 440–510 450–510 140–200

Nylon 6=6 470–550 480–540 480–540 490–530 520–540 510–540 140–200

PC 440–480 450–480 460–480 470–490 460–510 460–510 140–220

PC=ABS 420–445 430–455 440–465 450–475 440–490 450–490 120–220

PP General purpose 340–430 350–440 360–450 370–450 390–460 390–450 40–120

PS General purpose 340–360 360–390 390–420 400–440 360–450 360–440 40–120

PS High impact 370–390 390–420 420–450 430–470 420–460 420–460 40–120

PVC Flexible 250–290 260–300 270–310 280–320 310–375 310–375 50–100

PVC Rigid 280–300 300–320 320–350 340–370 330–390 340–390 50–100

TPE (Hytrel) 300–400 310–410 330–430 350–450 370–460 370–450 60–140

TPU 360–450 360–460 360–460 360–470 370–475 340–465 60–140

TPU=PVC (Vythene) 300–320 310–330 320–340 330–360 340–365 350–365 60–120

Temperature profiles of different plastics going through an extruder having six

temperature zones.

MULTIPLE 3D PARTING LINES PARISON

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Multiple Parting Lines

conventionally pinch welding the flashed plastic on all sides of the bar. The part is

blow molded. Part ejection is achieved by pulling the separator off the third member

or by retracting the third member out of the part undercut prior to mold opening.

Reciprocating the third member is an option which would be desirable to form

deep undercut parts. This was evaluated and found unnecessary for this particular

part.

Production rates are the same as with any other part that is prepinched and preblown.

Rates depend on wall thickness, part geometry, surface appearance, flatness, etc.—all

the same factors that control cycle times for any large blow molded part.

Because of the greater amount of pinch welding in this technology, greater press

clamping force than usual would be helpful. The amount of flash trimming is

proportionally increased by the amount of pinch blade length. Good pinch blade

quality is important to this methodology.

Preblowing parisons between split mold sections results in parts that inherently have

more trimmed offal to be granulated. There is an added cost for the extra regrinding;

however, this is not a high cost if normal blow molding temperatures are used, the

trimmed offal is kept clean and handled efficiently.

Orienting 3D Parison

Blow mould and nonaxisymmetric blow mould. In conventional, the parison

enters the mold vertically rather in a straight tube. In 3D blow mould, the parison is oriented

in the open or closed mold. It is manipulated in the tool cavity, providing complex

geometric products that can have uniform or nonuniform wall thicknesses, corrugated

and noncorrugated sections, and so on. It provides a means to significantly reduce

scrap=flash (etc.) waste and quality.

Plastic materials used for Blow Moulding Process

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1. Polyethylene

- Low Density Polyethylene

- Linear Low Density Polyethylene

- High Density Polyethylene

- High Molecular Weight, High Density

2. Polyethylene

3. Polypropylene

- Homopolymer

- Random Copolymer - Impact Copolymer

4. Polyvinyl Chloride

5. Polyethylene Terephthalate

6. Polycarbonate

Material for Blow Moulding

Melting the material with the following properties suitable for blow molding applications:

> Hot enough stability for the processing temperature range and, if necessary, to the processing of repeated

> Enough in terms of homogeneous, plasticated melt.

> Stretchability enough tube even at high speed stretch.

> Good repeatability and long-weight ratio

> Surface smooth comparison.

> Compatibility with additives such as masterbatches, pigments, etc.

> Various processes are sufficiently broad to complete the required properties section.

> Excellent much consistency much.

Based on the Material Requirements Compliance.

Extrusion Blow Moulding

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Extrusion blow molding is used to treat a variety of different polymers including polyethylene, polyvinyl chloride, polypropylene and much more. This process begins with under conventional extrusion tube. When the tube reaches the desired length of the mold is closed to catch and hold the open end of the neck and pinched the bottom closed. Then puffs pin inserted into the neck end of the heat tube to form a threaded opening and expanding the tube in the mold cavity. When the mold is completely cooled opened to remove the excess plastic bottles and trimmed from the neck and bottom areas.

Stretching gust Moulding

The main stretch blow molding applications including bottles, packaging and the like, produce visual quality goods and excellent dimensional compared to extrusion blow molding. The first process requires plastic to be injection molded into a 'preform' with a threaded neck finish of the bottle at one end.

Puffs to enlarge

The preform is then heated and blown, using high-pressure air, into the bottle using a mold. At the same time the preform is drawn with a core rod to fill the mold. Strain hardening occurs as part of the process of stretching several polymers, Polyethylene Terepthalate which allows the bottle to resist deformation under pressure resulting from carbonated beverages, usually around 60 psi.

General Processes

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BLOW MOLD - general sense

Blowing process is mainly used for making thin-walled container. A cylindrical plastic material called porison extruded as soon as possible and clamped at the end of the mold. At the time the mold is closed porison closed porison cut and due to air pressure, the material pressed into the mold surface. mold must have adequate airway smooth the surface of the product. As soon as the product is cool enough, the mold is opened and the product diketuarkan.

Blow molding process similar to the process of making the Framework bottle glass industry. A pipe made of extruded thermoplastic material induction into the open mold. Both ends of the plastic pinched and closed when the mold is closed and pressed air flowed into the empty pipe metatui pipe in the center of the head mold. Compressed air is developing plastics that are attached to the walls of the mold. Setetah in chill for a while, as long as the plastic is still under pressure, the air pressure is lowered and the mold is opened. Bottles are removed from the mold and machine prepared for the next cycle. For some types of plastic, bottles must be cooled to room temperature. The top and bottom of the bottle and then cut to dispose of plastic that is outside of the product but is still in the mold area.

Packaging for cosmetics, bottles, petampung, heating ducts in motor vehicles, botot botot liquid detergent and hot water are examples of blow molding products. Raw materials such as polietiten, polypropylene and can be used under the Framework selutosa asetan pross this blow-molded.

This species is also a continuous process in nature and are very often used to mold with a product that has a thin thickness and also with a thin neck such as bottles, cisterns, etc. Sort of dough plastic pipe with a predetermined length and then extruded. One side of the pipe is then laid on inflatable pin. Then the two parts of the blow mold sealed. Then betekanan air is then blown into the pipe before the pipe which then expands to follow the shape of the mold. Setetah cooling down, then the two parts of the blow mold is opened, and the product is issued. Most thermoplastics such as LDPE, HDPE, PP, PVC, PET, Polycarbonate can be processed using this technique.

PROCESS OF PLASTIC BOTTLE

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Plastic packaging currently dominate the food industry in Indonesia, shifting the use of metal and glass packaging. This is due to the excess of plastic packaging that is lightweight, flexible, multipurpose, strong, does not react, do not rust and are thermoplastic (heat seal), can be colored and the price is cheap. The weakness of the plastic due to the substance of the monomers and small molecules of plastic that may migrate into foodstuffs. Plastic objects we find in almost all areas, ranging from food wrappers, electronic equipment, automobiles, motorcycles, household appliances and so on.

Plastics are often distinguished by the resin, as between the plastic and resin unclear

difference. Naturally, the resin can be derived from plants such as balsam, resin, turpentine. But now resin synthesis can be produced for example cellophane, celluloid acrylic, formica, nylon, phenol formaldehyde resin, and so on.

Material Plastic makers in the beginning was the oil and natural gas as a source, but in the development of these materials are replaced with synthetic material so as to obtain the properties desired plastic by means copolymerization, and extrusion lamination.

Each type of plastic material and affect the manufacturing process and technology used in the manufacture of plastics. For example to make the parts electronics like mobile phone casing, gear on the printer, plastic cups, and the like objects used injection molding machine, to form a used press rubber shoe soles, while to make use bottle blow molding mold type. This time we will be in a familiar process of making plastic through injection technology and components that exist in the injection machine.

Discovery and manufacturing of plastics, was first reported by Dr.Montgomerie in 1843, namely the Malayan population by heating the rubber latex is then formed by hand and used as a handle of a knife. In 1845 J.Peluoze successfully synthesize nitric sululosa. The first mold plastic material, patented by JLBaldwin on 11 February 1862 which called the molds for making daguerreotype cases. The mold is then used widely for forming plastic materials that consist of a mixture of latex with various fillers, humectants and pemplastik.

Plastics manufacturing technology was developed in the 1800s. Then in 1868 John Wesley Hyatt making celluloid billiard ball by injecting into the mold. John and Isaiah Hyatt patented injection molding machine for the first time in 1872. Celluloid is used also for children's toys, clothes, paint and

varnish, as well as films for photos.

Injection molding is a thermoplastic material processing method which molten material for heating injected by the plunger into a mold which is cooled by water and then the material will be cool and harden so it can be removed from the mold.

Broadly speaking, the injection machine is divided into 3 parts:

1. Clamping Unit

Clamping unit serves to hold and organize the movement of the mold unit and ejector movement when removing objects from the molding unit. In the clamping unit is we can set how long the molding movement when opened and how long the ejector should move. There are two kinds of clamping units used in general, namely hydraulic toggle clamp and clamp.

2. Molding Unit

Molding unit is actually another piece of plastic injection machine. Molding unit is part of the shaping of objects made, Broadly speaking molding unit has two main parts: the cavity and core. Section is part of the mold cavity associated with a nozzle on the machine, while the core is the part relating to the ejector.

3. Injection Unit

Parts of the injection unit are:

a. Motor and transmission gear unit

This section serves to generate power used to rotate

screw on the barrel, while the transmission function to remove power from the motor to the screw. Besides transmission unit also serves to regulate power supplied to the load is not too large.

b. Cylinder screw ram

This section serves to facilitate the movement of the screw by using enersia moment while keeping the screw remains constant velocity so obtained generated a constant speed and pressure during the process of plastic injection is done.

c. Hopper

Hopper is a place to put the plastic material before entering the barrel. Usually to keep moisture plastic material used special storage area that can regulate humidity because if the water content is too big in the air, can cause injection results are not good.

d. Barrel

Barrel is a screw and a sheath that keeps the plastic flow when heated by the heater. In this section there is also a heater for heating the plastic before entering into the nozzle.

e. Screw

Reciprocating screw serves to drain the plastic from the hopper to the nozzle. When the screw rotates the material from the hopper would be interested in filling screw which further heated and then pushed toward the nozzle.

f. Non-return valve

This valve serves to maintain the flow of melted plastic so as not to come back when the screw stops rotating.

PROCESS OF BOTTLE (Blow Mold Technology)

The manufacturing process begins with the formation of a plastic material by way of blowing a fluid (air) into a mold to form a shape that is desired. Generally used for the formation of a hollow with a wall thickness difference.

Blow Mold method can be divided into three ways, namely:

1. Injection Blow Mold

The process of formation of plastic products by means of injected plastic prior to going to be on the blow. Consists of components Injection and Blow. Generally used for containers with a relatively small size and that there is absolutely no handle. Often also used for containers which are formed by a screw on the bottle neck.

Process Stages:

a. In a state of melting plastic is injected into kaviti in the form going.

b. Plastic moved to mold blowing.

c. The air breathed so that the plastic expands and attaches appropriate mold shape.

d. Mold opening for product release.

2. Extrusion Blow Mold

The process of formation of a plastic material by way dripped from the extruder. The simplest method of blow mold consists of extruder and blow. Can be used for containers of varying shape, size, opening the bottle neck, as well as the formation of the handle. The type of plastic used is HDPE, PVC, PC, PP, and PETG.

Process Stages:

a. Plastic removed from the extruder into the blow mold with directional holes.

b. Closed mold.

c. Steering fluid drain holes (air) into the melting plastic in a state so pressing to mold.

d. Open mold for product release.

3. Stretch Blow Mold

Plastic forming process in this way stretch (stretch) until the desired size is achieved by considering the thickness of the plastic feeder. Very good for the type of PET plastic. Consists of components Injection, Stretcher and Blow.

Process Stages:

a. In a state of melting plastic is injected into kaviti in the form going.

b. Plastics in stretching (stretched) suitable dimensions required.

c. The air breathed so that the plastic expands and attaches appropriate mold shape.

d. Mold opening for product release.

Simply put bottles are generally made of materials such as plastic and glass. The process of making a bottle of the two materials is almost the same. The molten material then blown into a mold according to the desired shape. The following details the manufacturing process of the glass bottle:

1. The materials to make the bottle, such as calcium carbonate, sodium carbonate, silica sand, and other chemicals in the input into the furnace (furnace).

2. In the furnace burning these materials in melting temperature of up to 1400 degrees Celsius.

3. The results of this fused (gob) in feed into the mold.

4. In this mold is fused in blow with the wind pressure so that the liquid glass sticks to the mold to form the desired bottle (see picture).

5. Once the bottle off of the mold and then in doing reheating (heat treatment) to eliminate stress and strain when forming the bottle. This treatment is given so that the maximum strength of the bottle.

This is the basic way of making the bottle. In the factory all the system runs automatically and can produce thousands of bottles in every hour.

BLOW MOLD CLASSIFICATION

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Blow molding is the collective term for the production of hollow article in thermoplastics material by various methods whose common characteristic is the inflation of preform,or parison,inside a shape-giving blow mold .it has forerunner in the glass industry.

ONE DIFFERENTIES BETWEEN:
#Blow molding in a flowable state within the thermoplastic temperature stage.

#Streth blow molding in the thermoplastic temperature range.

In principle one can expert a greater blow up ratio as well as greater fredom in design of the blow molded article an blow mold with material in the termoplastic temperature range,whereas one obtains considerably more strength in the thermoplastic range.
The processing base classification of blow molding techniques resuts in two essentially different metode:
#Production of preform (parison) and subsequent transfer in molddable condition into the blow mold(singgle-stage process).
#Heating of the separately produced parison an sub sequent transfer in molddable condition into the blow mold(two-stage process).

*Extrusion Blow Molding.

*Injection Blow Molding.

*Dip Blow Molding.

The extrusion blow molding process has attained the greatest importance by far.The pressent state of the technology spans an extrusion blow molding range from 1 ml to 10 m3.The injection blow molding and dip blow molding processes are limited to producing articles of 10 ml to 101 or 11 content respectively and to the production of holowware of relatively simple shape.

EXTRUSION BLOW MOLDINGBasic Design Guidelines

The essential design charateristcs of the blow mold relate to the shape of the hollow article to be produced and the most faroable method of introducing the blowing medium.
Etrusion with parison lenght variation or timer controlled variation of the die gap accommodate longitudinal differences in wall thickness of the blow molded article and the sectionwise of the die gap to provide crosswise wall thickness variations are part of today's tecnhology.
The blowing pressure is usually in the region of 2 to 20 bar (30-300psi ),preferably 5 to 10 bar ( 75-150 psi ).This requires a clamping force of at least 100kN ( approximately 10 tons ) per unit pressure and square meter of the projected area on the mold mounting platens.
These data are of particular importance for the design of design of blow molds when the weight of the mold is of prime consideration.

MOLD MATERIAL

It is essential to classify the mold materials according to the size and the number of article required.
Here the following subdivisions are useful :

+ Blow mold for continous production and large batches
+ Blow mold for small batches and prototype production

Only metal molds can be considered for continous production and long runs,whereas for small batches and prototypes,casting resins in water permeable backed shell contruction are also suitable.
With metals it is necessary to further subdivide into tool steels,aluminium,beryllium and zinc alloys.Fastenings and guide components and,if possible also the areas of hight edge inserts should in addition be hardened.
Tool steels should be considered mainly for long production runs in the volume range of up to 10 liters.The blow mold is produced by machining.Any of the steel types generally used in plastic processing can be chosen.If blow molding plastic contain corrosivee volatiles,it is necessary to employ corrosion or acid resistant steels.Apart from the exeptions alreadymentioned,hardening is not necessary and crome plating is not customary.For large volume articles with a content of three cubic meters and up welded machined plate contruction can also be considered.Cast steel is of no value for mold base.

Given the right care,the life span of steel blow molds isgreater thanthe longest production run achieved up to now ( 10'7th parts per blow mold ).Inserts subject to wear and tear either have to be refurbished or exchanged at intervals of 10'5th or 10'6th cycles.

The advantages of blow molds produced in aluminum,berylium and zinc alloys include excellent thermal conductivity,low weight and economical manufacture by precision casting.These material should be considered mainly for blow molding in the range from 10 liter volume and up,but they can also be used for mass production of smaller hollow articles if they are equipped with steel inserts.Plating may be considered where processing of plastics materials containing corrosive volatiles is a problem,in which case even gold plating has been suggested.Due to the reduced strength and hardness,damage to edge and surfaces can easily be cause.With proper care,life spans of 10'5th to 10'6th cycles be expected.

MOLD PARTING LINE and INSERTs

The blow mold should be parted in technologically most suitable plane for the hollow article.As a rule one obtains two equal or mirror image halves,equally divided.With asymmetrical and awkwardly spaced angled blow molded articles the location of the parting line is the determined by the most farorable blowing position and the avoidance of ejection difficulties caused by undercuts.That type of blow mold tool may also require several parts or inserts e.g.bottom inserts that may rotaye or be able to slide against each other.These may be actuated by compressed air or hydraulic cyliders or by means of synchronous cams.Loase insert in dovetail guides that are ejected with the blown molded article for rause may also be considered.

Cylindrical articles are parted along the axis of rotation and elliptical shape along the large diameter.Cube shape articles can be parted along the diagonals or parallel to the side faces.Diagonal parting may permit a smaller,more favorable blow ratio,but it results in an excessive stretching in the corners opposite the parting plane with a corresponding thinning out in these places on the article.

Assembled mold halves and inserts should be designed so that the joints donot show on the molded part.It is well known that even perfectly flush assembly can cause visible lines on the molded part.The joins runs along the area of the standing rim and at the top along the portion of the neck covered by the closure.

Of the multitude of mold inserts,only the bottom and neck inserts, the edge and knife inserts for welding,cutting and trimming and the replaceable plate and punches containing engravings and other markings will be mentioned.All inserts subjected to high edge loading during the clamping of the parison should be hardened to 60-62 RC.

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