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LEAN STARTUP

2018-04-02T07:24:00.005-07:00

Stop me if you’ve heard this one before. Brilliant college kids sitting in a dorm are inventing the future. Heedless of boundaries, possessed of new technology and youthful enthusiasm, they build a new company from scratch. Their early success allows them to raise money and bring an amazing new product to market. They hire their friends, assemble a superstar team, and dare the world to stop them.

Ten years and several startups ago, that was me, building my first company. I particularly remember a moment from back then: the moment I realized my company was going to fail. My cofounder and I were at our wits’ end. The dot-com bubble had burst, and we had spent all our money. We tried desperately to raise more capital, and we could not. It was like a breakup scene from a Hollywood movie: it was raining, and we were arguing in the street. We couldn’t even agree on where to walk next, and so we parted in anger, heading in opposite directions. As a metaphor for

our company’s failure, this image of the two of us, lost in the rain and drifting apart, is perfect.

It remains a painful memory. The company limped along for months afterward, but our situation was hopeless. At the time, it had seemed we were doing everything right: we had a great product, a brilliant team, amazing technology, and the right idea at the right time. And we really were on to something. We were building a way for college kids to create online pro􀀡les for the purpose of sharing … with employers. Oops. But despite a promising idea, we were nonetheless doomed from day one, because we did not know the process we would need to use to turn because we did not know the process we would need to use to turn our product insights into a great company.

If you’ve never experienced a failure like this, it is hard to describe the feeling. It’s as if the world were falling out from under you. You realize you’ve been duped. The stories in the magazines are lies: hard work and perseverance don’t lead to success. Even worse, the many, many, many promises you’ve made to employees, friends, and family are not going to come true. Everyone who thought you were foolish for stepping out on your own will be proven right.

It wasn’t supposed to turn out that way. In magazines and newspapers, in blockbuster movies, and on countless blogs, we hear the mantra of the successful entrepreneurs: through determination, brilliance, great timing, and—above all—a great product, you too can achieve fame and fortune.

There is a mythmaking industry hard at work to sell us that story, but I have come to believe that the story is false, the product of selection bias and after-the-fact rationalization. In fact, having worked with hundreds of entrepreneurs, I have seen 􀀡rsthand how often a promising start leads to failure. The grim reality is that most startups fail. Most new products are not successful. Most new ventures do not live up to their potential.

Yet the story of perseverance, creative genius, and hard work persists. Why is it so popular? I think there is something deeply appealing about this modern-day rags-to-riches story. It makes success seem inevitable if you just have the right stu􀀯. It means that the mundane details, the boring stu􀀯, the small individual choices don’t matter. If we build it, they will come. When we fail, as so many of us do, we have a ready-made excuse: we didn’t have the right stu􀀯. We weren’t visionary enough or weren’t in the right place at the right time.

After more than ten years as an entrepreneur, I came to reject that line of thinking. I have learned from both my own successes and failures and those of many others that it’s the boring stu􀀯 that matters the most. Startup success is not a consequence of good genes or being in the right place at the right time. Startup success can be engineered by following the right process, which means it can be engineered by following the right process, which means it can be learned, which means it can be taught.

Entrepreneurship is a kind of management. No, you didn’t read that wrong. We have wildly divergent associations with these two words, entrepreneurship and management. Lately, it seems that one is cool, innovative, and exciting and the other is dull, serious, and bland. It is time to look past these preconceptions.

Let me tell you a second startup story. It’s 2018, and a group of founders have just started a new company. Their previous company had failed very publicly. Their credibility is at an all-time low. They have a huge vision: to change the way people communicate by using a new technology called avatars (remember, this was before

James Cameron’s blockbuster movie). They are following a visionary named Will Harvey, who paints a compelling picture: people connecting with their friends, hanging out online, using avatars to give them a combination of intimate connection and safe anonymity. Even better, instead of having to build all the clothing, furniture, and accessories these avatars would need to accessorize their digital lives, the customers would be enlisted to build those things and sell them to one another.

The engineering challenge before them is immense: creating virtual worlds, user-generated content, an online commerce engine, micropayments, and—last but not least—the three-dimensional avatar technology that can run on anyone’s PC.

I’m in this second story, too. I’m a cofounder and chief technology officer of this company, which is called IMVU. At this point in our careers, my cofounders and I are determined to make new mistakes. We do everything wrong: instead of spending years perfecting our technology, we build a minimum viable product, an early product that is terrible, full of bugs and crash-your-computer-yes-really stability problems. Then we ship it to customers way before it’s ready. And we charge money for it. After securing initial customers, we change the product constantly—much too fast by traditional standards—shipping new versions of our product dozens of times every single day.

We really did have customers in those early days—true visionary early adopters—and we often talked to them and asked for their early adopters—and we often talked to them and asked for their feedback. But we emphatically did not do what they said. We viewed their input as only one source of information about our product and overall vision. In fact, we were much more likely to run experiments on our customers than we were to cater to their whims.

Traditional business thinking says that this approach shouldn’t work, but it does, and you don’t have to take my word for it. As you’ll see throughout this book, the approach we pioneered at IMVU has become the basis for a new movement of entrepreneurs around the world. It builds on many previous management and

product development ideas, including lean manufacturing, design thinking, customer development, and agile development. It represents a new approach to creating continuous innovation. It’s called the Lean Startup. Despite the volumes written on business strategy, the key attributes of business leaders, and ways to identify the next big thing, innovators still struggle to bring their ideas to life. This was the frustration that led us to try a radical new approach at IMVU, one characterized by an extremely fast cycle time, a focus on what customers want (without asking them), and a scientific approach to making decisions.

There Are So Many Things To Write

2018-04-02T03:44:00.005-07:00

That many of them go out of sight,

I lament for them,

But immediately I can not recall the same.

They may accuse me,

But I don't want to flee,

Nothing in this world is trivial,

Everything is somehow essential.

I appeal to them to forgive me

And encourage me with glee;

I must find out them patiently and cautiously

And depict them distinctly.

THE WORLD OF POETRY

2018-04-02T03:43:00.001-07:00

The World Of Poetry

The poets write poetry

And fill the world with vitality,

They may sleep in the cemetery,

But their existence for ever is a reality.

The poets depict their imagination independently

And the readers read it in an ecstasy,

The world of poetry moves confidently,

As the poets are superior to their fancy

No one can live without poetry,

As it will destroy his or her tranquility.

THE WILD ANIMALS IN THE CIRCUS

2018-04-02T03:40:00.000-07:00

In the big ground the circus is in full swing,

The people enjoy it greatly and spring,

The clowns and the wild animals are busy in their work,

The lions, the tigers, the elephants are sharp,

But with the drudgery of work

They have certainly lost their glory and spark.

The wild animals are wild in nature and stature,

But they can not be so in this sphere,

As they have been well trained to behave in this submissive way,

From the strict and rigorous hand they can never sway.

The clowns are obliged to play their role in the circus,

But we are the most significant clowns of the world,

As we enjoy here the wild animal's living carcass.

THERE IS NO WAY TO ESCAPE

2018-04-02T03:30:00.000-07:00

There is no way to escape,

Though the sages always think for this sake,

The fact is beyond control,

we have already begun to crawl.

Presently 'Progress' is not so in the true sense,

As it has lost the features of its essence,

In fact, we have developed our eccentricity

And the word 'dignity' is no more our identity.

Enmity and violence have destroyed our society,

We are now put in its captivity,

The divine blessings should fall on this land

To remove from here the filthy sand.

METHODS OF CASTING'S

2018-04-02T03:23:00.002-07:00

Methoding of castings is a complex science. It involves the basic selection of :

(i) Design and construction of pattern equipment

(ii) Processes and practices for moulding, core making and core setting

(iii) Risering and gating system

Apart from the above technical parameters, clue consideration

sl poi ld be given for economic factors while methoding the castings.

The following points should be considered :

1. Type of moulding and core making process

2. Position of the casting in the mould box

3. Suitable joint line

4. Suitable mould box size

5. Type of mould and core making materials

6. Material specification

7. External and internal chills if permissible

8. Chaplets if permissible

9. Mould and core checking and setting gauges

10. Sequence of core setting

11. Provision of vents and flow offs.

12. Number of pieces to be produced

13. Type of material for pattern and core boxes

14. Pattern and core box details

15. Placement of identification codes

16. Indication of surfaces for marking and machining

17. Estimated yield percentage of the castings

While deciding the suitable method of manufacturing the intricacies of the concerned job should be analysed from all the angles and the final acceptable casting concept decided, considering the resources available within the foundry.

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2018-03-06T09:34:00.001-08:00

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TYPES OF CORE COATING

2017-08-07T23:39:00.000-07:00

1. Brushing and Swabbing

Brushing and swabbing methods of applying coatings are used in many foundries. The effort imparted by brushing helps to force the refractory particles into the pores of the sand surface, which is a desirable feature. The swab is a most useful aid in coating interior of difficult pockets and re-entrant angles. Both methods give uneven thickness and strives from brush motion is visible on casting. They also depend on the skills of the operator. There is also the risk of sand-coating mixture due to frothing and this ini-tiates metal penetration .

2. Spraying

Spraying is a much faster means of application widely used in foundries of all types. It is important to pay greater attention to the coating composition because less me-chanical effort is available to force the particles into the pores between the sand grains. Selection of the solid constituents and the overall viscosity is more critical for sprayed coating than for brushing and swabbing. Spray methods use specially designed guns to atomize the coating into a fine spray. This method along with brushing suffers the disability of not being able to coat deep re-cesses thoroughly. One reason for this is the back pressure of air which prevents refractory deposition in the cavity. The system of airless spraying provides a means of overcoming this disadvantage. Airless Spray has higher transfer efficiency and lower chance of blowback. Again, it is more efficient when a flat surface is involved which is also placed vertically during spraying.

The above discussion refers to liquid coating mixture however, a group of researchers from Austria developed a new method of spraying dry coating on substrates over-coming the inherent disadvantages of the use of wet coating. The process is called electrostatic or tribostatic powder spraying method, also designated as EPS method. In this process, the surfaces of the substrate is first made conductive (if it is not a conducting material) by spraying electrically conducting polymer solutions on them. Then the powder coatings can be applied. According to the developers, this novel coating process has been tested on all popular binder systems—from cold box, through hot box and furan to inorganic types .

3. Dip Coating

Dip coating techniques can be described as a process where the substrate to be coated is immersed in the liquid or coating and then withdrawn with a controlled speed under controlled temperature and atmospheric conditions. Coating thickness increases with a faster withdrawal speed. The deposited thickness is determined by the bal-ance of forces at the stagnation point on the coating sus-pension surface. The faster the withdrawal speed the more coating suspension is pulled up onto the substrate surface because there is no time for the suspension to flow back down to the coating pool. During sol-gel dip coating, the coating suspension is rapidly concentrated on the surface of the substrate by gravitational draining with associated evaporation and condensation reactions. Dip coating is usually used for cores and is well suited for automatic applications. Dip coating enhances a high production rate and high transfer efficiency (almost 100%) and relatively little labour is required. The effectiveness of dip coating depends greatly on the viscosity of the coating, which thickens with ex-posure to air unless it is carefully managed. The viscosity of the coating must remain practically constant if the deposited film quality is to remain high and the same. To maintain viscosity, solvent must be routinely added as makeup. This results in high volatile organic compounds (VOC). Dip coating is not suitable for objects with hol-lows or cavities . Other factors that determine the effectiveness of dip coating include coating density and surface tension. Better surface penetration is obtained than with spraying because of the head pressure of the coating in the dip tank. Even thickness of surface is necessary so as to maintain dimensional accuracy and true reproduction of contour. Uneven coating is at its worst when it runs down as tears. This defect can be encouraged by the nature of the surface to be coated but is mainly due to the kind of the suspension agent used in the coating. Tears and similar coating faults are sources of high gas evolution and cast-ing defects may result. The coating can be cured by a number of methods such as conventional thermal, UV, or IR techniques depending on the coating formulation

4. Flow Coating

Flow coating is a method of applying a refractory coating that can be described as wetting the moulds or heavy cores with a garden hose at low pressure. With flow coating the mould or core is maneuvered so it is at an angle (20 to 40° to the vertical) in front of the operator and coating applied through a hose, starting at the top and in lateral movements progressively working down to the bottom. Flow coating is usually used for large or oddly shaped parts that are difficult or impossible to dip coat. Coatings applied by flow coating have only a poor to fair appearance unless the parts are rotated during drip-page. Flow coating is fast and easy, requires little space, involves relatively low installation cost, requires low maintenance, and has a low labour requirement. Required operator skill is also low. Flow coating achieves a high coating transfer efficiency, often 90% and higher. Prin-cipal control of dry-film thickness depends on the coating viscosity. Flow coating can eliminate all the various problems associated with the other coating techniques such as spraying, dipping or brushing. For flow coating to be effective, it must create a surface and sub-surface coating. Surface coating provides a barrier to the metal and improves surface finish. The sub-surface coating penetrates the surface of a mould or core to fill the voids between the sand grains. This reduces the possibility of metal penetration and veining

Flow coating method, it is seen that the mould is inclined at an angle.

5. Drying of Coating

After coating application, each coating must be ‘dried’, which means that the suspension agent (water, alcohol or volatile agents) must be completely removed. These sub-stances do penetrate the mould or core material and do not have any protective effect for the mould or core. On the contrary, it can cause severe problems of gas forma-tion, blows, slag entrapment, porosity, blistering, and penetration and drastically reduce the strength of the mould or core. The methods of removal are different depending on the type of coating.

5.1. Drying Organic Solvent-Based Coatings

In the past, foundries typically used solvent-based carri-ers because they dry quickly without external heating (air drying). They are also referred to as self-drying coatings. This takes a lot of time. Consequently, flame torching became the accepted means of drying coated cores and moulds. However, workplace environmental, health and safety concerns, as well as economic consid-erations emanating from the rapidly increasing cost of petrochemicals based solvent, continue to enhance the development and use of water-based coating technolo-gies .

5.2. Drying Water-Based Coatings

The trend today is towards water-based coatings. But they require longer drying times using air drying and conventional ovens compared to organic solvent-based coatings. The drying temperature must exceed 100°C, but lower than the temperature at which the binder system is destroyed (mostly 250°C).Different drying tech-niques such as high intensity lights, microwave, drying tunnels and infrared ovens can be applied to water-based coatings. It was reported in [40] that the high intensity lights and drying tunnels did not dry fast enough as ex-pected to prevent coatings from dripping and losing thickness uniformity. Microwave drying used non-selec- tive heat that penetrated the sand cores and caused them to disintegrate. Infrared ovens, however, dry the coated cores or moulds quickly without damaging the sand bod-ies. Application of infrared heating for mould and core coating can reduce drying time by 85%. The energy sav-ing comes from the controllability of the infrared unit, which brings the mould surface to the desired tempera-ture and then cycles off in a predetermined time sequence. Less heat is dissipated to the surroundings. The infrared elements direct the heat more effectively at the mould and can dry deep cavities and mould pockets – thus con-tributing to better casting quality. The sub-surface of the mould is not affected. An additional advantage of using infrared heating is that only 25% of the floor space occu-pied by the resistance oven was required. A signifi-cant development in water-based coatings is the feature in which there is a distinctive colour change as the coat-ing dries and transitions from the wet to the dry state as shown in Figure. This change in colour offers visual confirmation that the coating is dry. Not only that this shows when drying is complete, it can also serve as a quality control tool. When drying takes longer time than necessary it will mean that the moisture content is high and can be adjusted. This feature saves energy used in drying thereby saving cost.

CHARACTERIZATION OF COATINGS

2017-08-07T23:35:00.001-07:00

Characterization of Coatings

In order to understand the behaviour of coatings contain-ing refractory materials, there is need for characterization of the coatings. The parameters that characterize foundry coatings are discussed below.

6.1. Specific Gravity

Specific gravity is the unit weight per unit volume. Spe-cific gravity is a quick test that allows inferences to be drawn about the total solids and refractory components present in the coating . The knowledge of the spe-cific gravity of the suspension agent and that of the re-fractory material is critical. There would be no difficulty in keeping the refractory material in permanent suspen-sion in the suspension agent if they have similar specific gravity . The specific gravity also gives a fair idea of the refractory material content of the coating. Water has a lower specific gravity of 1. When it used to dilute a coating with relatively higher specific gravity component; the specific gravity of the coating is reduced.

2. Viscosity

Viscosity, a measurement of material flow properties, is the best test for evaluating coatings because of its high correlation with the dried deposit on the core. There are several different methods of measuring viscosity. The most commonly applied in foundries is the flow cup method as shown. The flow cup measure of viscosity requires the use of a cup with a specific size of hole in the bottom to match the material being used. A stopwatch is used as the cup is lowered into the coating and then taken from the surface of the coating after it has filled. The time it takes the coating to drain through the hole is the viscosity in number of second

3. Baume´ Parameter

The Baume´ test is the most common test used in foun-dries to control coating because it is quick and easy. The test is performed with a hydrometer. It usually consists of a thin glass tube closed at both ends, with one end enlarged into a bulb that contains fine lead shot or mer-cury. The glass tubular end contains a calibrated scale in degrees Baume. The Baume scale of numbers relates to the specific gravity and body of a coating. After mixing the coating sample thoroughly, the hydrometer is imme-diately floated in the coating slurry. When it stops sink-ing, the degrees Baume is read directly from the hy-drometer scale. Baume is a simple test to help measure dilution consistency. However, there is a poten-tial for operator variability, and test parameters must be carefully controlled. Operator consistency in placing the hydrometer into the coating and length of test time are critical. When Baume test is used in combination with the specific Gravity measured by Gravimetric method, the combined results can be a more useful diagnostic tool. Many metal casting facilities also include viscosity test in their refractory coating control test procedures . L.

Winardi et al., reported that coating viscosity is typically reported in degree Baume. Higher Baume´ number indicates higher viscosity.

It was also reported in that Baume when per-formed in a controlled laboratory environment tracks well certain coating properties.

6.4. Solid content

The solids in the coating must be measured because they are the refractory materials that provide protection to the core or mould. The higher the percent solids, the more protection the coating offers. The solid content of a coat-ing determines some other important parameters of the coating such as the density, viscosity, thickness, cover-age etc. Therefore, the knowledge of the amount of solid in the coating is very important for reproducibility of these properties. The percent solid content can be de-termined by dividing the weight of the dried coating by the original weight and multiplying by 100.

6.5. Colloidal Stability

Colloidal stability is describing the formation of uniform suspension of the particles in the coating matrix. The stability of particles is determined by their resistance to aggregation.

The formation of uniform suspensions of particles can be understood by calculation of the sedimentation rates assuming that the particles are spherical so that Stokes’s Law may be applied. Equating gravitational and fric-tional forces:

The stability of small particles is surprising, since sur-face tension leads to very high pressure differences across surfaces with small radii of curvature. For a parti-cle of radius r, density ρ, and relative molar mass M, with surface tension γ, the pressure difference across the curved surface, pr, compared to that across a flat surface, po, is given by the Kelvin equation.

Thus small particles should tend to dissolve while lar-ger particles should grow as observed in Oswald ripening of precipitates.

6.6. Coating Thickness

Coating thickness is usually measured using a destructive test. To date no reliable non-destructive test is being ap-plied by the foundry industry to measure the consistency of the coating layer thickness applied on the cores or moulds. In some tests, the cores are sectioned and the measurements were taken using a microscope.

In some other methods, the coating is removed from a flat surface on a core and the difference in the cored sur-face and the coated surface is measured.

The amount of surface deposit can be used as a refer-ence for future comparisons and making decisions about coating allowance in casting design. There is a strong correlation between the viscosity of the coating and the coating thickness. However, coating dry thick-ness has proved difficult to measure, so what is generally done is to measure the wet coating layer thickness using the elcometer wet film “comb” as shown in Figure 10. The elcometer wet film combs can be used in accordance with following standards; ISO 2808-7B, ASTM D 4414-A, BS 3900-C5-7B and NF T30-125. The film combs have various lengths on their sides. These stan-dards specify that wet film comb be perpendicular to the substrate and the thickness of the coating lies between the biggest value wet tooth and the smallest value dry tooth values . The wet coating layer thickness will be correlated to the dry coating thickness, if the volume to solids ratio of the coating is known . As a rule of thumb dry coating thickness is 50% of the wet coating thickness.

In dip coating, the coating thickness is mainly defined by the withdrawal speed, the solid content (density), the surface tension and the viscosity of the liquid. The coat-ing thickness can be calculated from landau-Levich equation. This equation gives the wet coating layer thickness on a vertically withdrawn flat plate.

where hw = Wet coating thickness

υ = withdrawal speed

ρ = density

γLV = Liquid-vapour surface tension

g = acceleration due to gravity

To calculate the dry film thickness these equations need to be modified. It was reported in [51], that Yan et al. derived Eq. (4) for dry film thickness, hd

6.7. Coating Penetration Depth

The distance the coating penetrates the core is an impor-tant feature to a coating’s success. A coating that lies entirely on the surface of the cores is not anchored well and will most likely spall away. A coating that penetrates too much will over degrade the core. Coating penetration is also a function of core density. A core that is blown too tightly resists coating penetration, while one blown softly acts like a sponge and absorbs much water. There-fore, any evaluation of coating penetration should be done on a core that is of normal production quality. It is also note worthy that core release agents may waterproof the core and affect coating penetration. Coating penetra-tion is evaluated by cutting a coated dried core and ob-serving how far the coating penetrates the core. The usual reference is sand grain penetration. A normal level of penetration is 2 – 4 sand grains . It was reported in, that this is not the most precise methodology be-cause sand grain sizes differ from one foundry to the other. Moreover, a batch of foundry sand has a known distribution of a variety of grain sizes within it, which also makes using sand grain count as a measuring system inadequate. Lower surface tension increases the depth of coating penetration. As coating penetration increases, the thickness of the proud layer decreases while the reverse is the case if the proud layer increases. Thermal ex- pansion increases with the thickness of the proud coating layer (the layer on the surface of the substrate). Therefore, an optimum proud layer thickness is needed to reduce the expansion defects on the casting made with these cores. This requires that the coating penetration depth is controlled.

6.8. Coating Permeability

Coating permeability is the amount of gas that can pass through the coating. The level of permeability is detected by both the type and amount refractory materials that are used in the coating formulation and the dry film thick-ness deposit on the core. The permeability of the coating on the core is measured using a laboratory permmeter. A coating with low permeability is desirable when directing evolved gases to vent through specific areas of the core. A high permeability coating is best when the goal is the evacuation of core gases through the coating. The per-meability of the coating at the coating-metal interface may be different than that measured on the core. Some constituents of the coating may quickly thermally de-compose leaving voids that result in higher permeability. Some may soften and flux resulting in lower permeabil-ity. High permeability coating will reduce the time required for removing the degradation products and will increase the metal fill velocity, often leading to blister and fold defects. Low permeability coating will slow down the metal velocity, which causes the molten metal to lose the adequate thermal energy required for com-plete pyrolysis, traps the degradation products and leads to misrun or partial fill. It has been reported in that mould filling times decreased with permeability of the coatings. A standard approach to characterize the per-meability of porous materials is to use Darcy’s law (Eq. 8), which relates volumetric flow and pressure gradients with the properties of the fluid and porous materials

small Reynolds number (Re). The upper limit is at a value of Re between 1 and 10. At a high Reynolds num-ber, the deviation from Darcy’s law will be observed. The Darcian permeability coefficient K indicates the ca-pability of the porous medium to transmit fluids. Theo-retically, the permeability coefficient only depends on the porous medium’s properties. At high pressures, the turbulent and inertia flow become more dominant so that Darcy’s law is no longer valid. The transition from the linear (Darcy’s law) to the nonlinear regime°Ccurs gradually as the Reynolds number increases. Therefore, the classical approach to macroscopically characterize the effect of inertia and turbulence on flow through real porous media is to use Forchheimer’s equation (Eq. 9), which includes parabolic parts in the equation consider-ing the influence of inertia and turbulence

where V = fluid velocity averaged over the total cross-section of the porous specimen (Q/A)

β = inertial parameter

ρ = density of the fluid

This equation macroscopically quantifies the non-linear effect. Research has shown that the deviation from Darcy’s law (which occurs at Re = 1 – 10) cannot be attributed to turbulence, and inertia forces are more appropriate to explain the deviation. The role of inertial effects over such a transition at high Re from linear to nonlinear flow in the pore space was success-fully simulated in the laminar regime without including turbulence effects However, the random aspect of the pore distribution induces a highly heterogeneous lo-cal flow which becomes turbulent at high Reynolds’ re-gimes

Core Degradation

Core degradation varies from coating to coating. The longer a core stays wet, the more core degradation will take place. So, it is the best practice to put cores into an oven heat zone as quickly as possible after the core is coated. Most coatings use surfactants as wetting agents to allow the coating to penetrate the proper depth. These surfactants change the surface tension of the water, mak-ing it worse for core degradation. To evaluate the effect refractory coating on core strength, dip one set of cores and leave the other set undipped. Place both sets in the drying oven until dry and allow them to cool to ambient temperature approximately one hour. Then, when cool, evaluate both sets of cores for strength. The comparative loss in strength of coated cores will most likely be sub-stantial. It was reported in that the strength of core and mould material will decrease about 30% with This is in agreement with the authors’ findings in the investigation of the strength of core materials. The pub-lication of these results is on the way.

6.10. Wettability and Surface Tension

The deposition of a coating on a solid substrate generates new interface between dissimilar materials and involves considerations of wettability, spreading, interface evolu-tion and adhesion. The wettability of a solid by a liquid is characterized in terms of the angle of contact that the liquid makes on the solid. The basic law governing the equilibrium of a liquid drop on a surface was formu-lated by Thomas Young σ.

The drop is shaped by the resultant forces pulling at the three-phase contact line of the drop, where the solid/liquid, liquid/gas and solid/gas interfaces meet, in the plane of the solid as shown in Figure 11. The forces (per unit length) acting at this line are the surface ten-sions and their balance yields the famous Young’s equa-tion.

where σSG , σSL and σLG are solid/gas, solid/liquid and liquid/gas surface tensions, respectively

According to Taylor’s depiction of liquid droplet shape on solid surface, the droplet height, h = 2asin (θ*/2), where a is the capillary length (a = (σ/ρg)1/2, σ, the liquid surface tension and ρ, its density, a = 2.7 mm for water). It shows that gravity g can affect drop shape be-sides the three phase forces. Only if the drop is small enough that the effect of gravity is negligible, which typically is the case for drops of millimetre size down to micrometres, the drop will have the shape of a spherical cap and the liquid/gas interface meets the solid surface at an angle θc, which is called the contact angle of a flat surface . The condition θ < 90° indicates that the solid is wetted by the liquid, such a surface is referred to as a hydrophilic surface and θ > 90° indicates nonwetting, and the surface is called a hydrophobic surface. Wet-tability of a solid surface is governed by the chemical properties and the microstructure of the surface. Wet-tability is mainly determined by its interfacial free energy (σSG). The greater, the free surface energy, the easier, the liquid can spread upon and vice versa.

Young’s equation applies to ideal surfaces that are perfectly smooth and devoid of all chemical and struc-tural inhomogeneities. The contact angle measured on a rough surface (called the Wenzel angle, θw) does not obey Young’s equation; it is related to the equilibrium (Young’s) angle θy , by Equation (11)

where r is the ratio of true wetted area to the apparent area. Equation (11) is called the Wenzel equation.

Wenzel’s equation applies to equilibrium angles on rough surfaces and not to advancing and receding angles of a droplet on a rough solid surface that give rise to contact-angle hysteresis. Hysteresis, H, is defined as the difference of the advancing and receding angles (i.e., H = θa - θr) and arises because the liquid-vapour interface does not retrace its original path when it recedes on the solid, so that spreading is thermodynamically irreversible. Because roughness hinders the contact line motion by creating energy barriers, the system can reside in any of the po-tential wells accessible to it that are commensurate with the vibrational (or thermal) energy of the droplet. In many industrial processes like that found in foun-dries, the substrate (core in foundries) is immersed in a liquid coating material, and then withdrawn to leave a liquid film on the substrate. The film (coating) thickness depends upon the surface tension, withdrawal speed, substrate geometry, roughness, and viscosity. The dis-persion of fine, granular solids in a liquid vehicle is a basic step in preparing paints and other coating materials and involves particle transfer across a gas-liquid interface. The transfer of non-wettable solids into liquids requires the solid to overcome a surface energy barrier at the liq-uid-gas interface, and energy must be expended to assist the transfer of non-wettable solids. Once the solid enters the liquid, the capillary (attractive) forces and gas bridges between solids control such phenomena as agglomeration, dispersion, and air entrapment. The inter-particle forces between dispersed solids are due to liquid surface tension and pressure difference across the curved liquid-vapour boundary between contacting solids. The maximum in-ter-particle force, F, due to capillary forces between two touching spheres where R is the radius of the sphere. The force increases with increasing liquid surface tension and decreasing contact angle and particle radius. These forces affect the viscosity, density, and sedimentation behaviour of the suspension and the properties.

METANOIA—A SHIFT OF MIND

2017-08-05T12:04:00.002-07:00

When you ask people about what it is like being part of a great team, what is most striking is the meaningfulness of the experience. People talk about being part of something larger than themselves, of being connected, of being generative. It becomes quite clear that, for many, their experiences as part of truly great teams stand out as singular periods of life lived to the fullest. Some spend the rest of their lives looking for

ways to recapture that spirit.

The most accurate word in Western culture to describe what happens in a learning

organization is one that hasn't had much currency for the past several hundred years. It

is a word we have used in our work with organizations for some ten years, but we always

caution them, and ourselves, to use it sparingly in public. The word is "metanoia" and it means a shift of mind. The word has a rich history. For the Greeks, it meant a fundamental shift or change, or more literally transcendence ("meta"—above or beyond, as in "metaphysics") of mind ("noia," from the root "nous," of mind). In the early (Gnostic) Christian tradition, it took on aspecial meaning of awakening shared intuition and direct knowing of the highest, of God.

"Metanoia" was probably the key term of such early Christians as John the Baptist. In the

Catholic corpus the word metanoia was eventually translated as "repent."

To grasp the meaning of "metanoia" is to grasp the deeper meaning of "learning," for learning also involves a fundamental shift or movement of mind. The problem with talking about "learning organizations" is that the "learning" has lost its central meaning in contemporary usage.

Most people's eyes glaze over if you talk to them about "learning" or "learning organizations."

Little wonder—for, in everyday use, learning has come to be synonymous with "taking in

information." "Yes, I learned all about that at the course yesterday." Yet, taking in information is only distantly related to real learning. It would be nonsensical to say, "I just read a great book about bicycle riding—I've now learned that." Real learning gets to the heart of what it means to be human. Through learning we re-create ourselves. Through learning we become able to do something we never were able to do. Through learning we reperceive the world and our relationship to it.Through learning we extend our capacity to create, to be part of the generative process of life. There is within each of us a deep hunger for this type of learning. It is, as Bill O'Brien of Hanover Insurance says, "as fundamental to human beings as the sex drive." This, then, is the basic meaning of a "learning organization"—an organization that is continually expanding its capacity to create its future. For such an organization, it is not enough merely to survive. "Survival learning" or what is more often termed "adaptive learning" is important—indeed it is necessary. But for a learning organization, "adaptive learning" must be joined by "generative learning," learning that enhances our capacity to create.

A few brave organizational pioneers are pointing the way, but the territory of

building learning organizations is still largely unexplored. It is my fondest hope that this

book can accelerate that exploration.

THE PRICE MUST BE PAID BY EVERYONE

2017-08-05T04:24:00.000-07:00

In Straight Talk for Monday Morning, Allan Cox observed, "You have to give up something to be a member of a team. It may be a phony role you've assigned to yourself, such as the guy who talks too much, the woman who remains silent, the know-it-all, the know nothing, the hoarder of talented subordinates, the non-sharer of some resource such as management information systems (MIS), or whatever. You give up something, to be sure, such as some petty corner of privilege, but you gain authenticity in return. The team, moreover, doesn't quash individual accomplishment; rather it empowers personal contributions." People who've never had the experience of being on a winning team often fail to realize that every team member must pay a price. I think some of them think that if others work hard, they can coast to their potential. But that is never true. If everyone doesn't pay the price to win, then everyone will pay the price by losing.

2. The Price Must Be Paid All the Time

Many people have what I call "destination disease." Some people mistakenly believe that if they can accomplish a particular goal, they no longer have to grow. It can happen with almost anything: earning a degree, reaching a desired position, receiving a particular award, or achieving a financial goal. But effective leaders cannot afford to think that way. The day they stop growing is the day they forfeit their potential—and the potential of their organization. Remember the words of Ray Kroc: "As long as you're green, you're growing. As soon as you're ripe, you start to rot."Destination disease is as dangerous for a team as it is for any individual. It makes us believe that we can stop working, stop striving, stop paying the price—yet still reach our potential. But as Earl Blaik, former football coach at the United States Military Academy, observed, "There is no substitute

for work. It is the price of success." That truth never goes away. That's why President Dwight D. Eisenhower remarked, "There are no victories at bargain prices." If you want to reach your potential, you can never let up.

3.The Price Increases If the Team Wants to Improve, Change, or Keep Whining

Have you ever noticed how few back-to-back champions there are in sports? Or how few companies stay at the top of Forbes magazine's lists for a decade? Becoming a champion has a high price. But remaining on top costs even more. And improving upon your best is even more costly. The higher you are, the more you have to pay to make even small improvements. World-champion sprinters improve their times not by seconds, but by hundredths of a second. No one can move closer to his or her potential without paying in some way to get there. If you want to change professions, you have to get more education, additional work experience, or both. If you want to run a race at a faster pace, you must pay by training harder and smarter. If you want to increase earnings from your investments, you either put in more money or take greater risks. The same principle applies to teams. To improve, change, or keep winning, as a group the team must pay a price, and so must the individuals on it.

4. The Price Never Decreases

the price that must be paid. But every person ought to know what to expect to pay in order for a team to succeed. For that reason, I offer the following observations about the cost of being part of a winning team. To become team players, you and your teammates will have at least the following required of you .

• Sacrifice: There can be no success without sacrifice. James Allen observed, "He who would accomplish little must sacrifice little; he who would achieve much must sacrifice much." When you become part of a team, you may be aware of some of the things you will have to give up. But you can be sure that no matter how much you expect to give for the team, at some point you will be required to give more. That's the nature of teamwork. The team gets to the top only through the sweat, blood, and sacrifice of its team members Time Commitment: Teamwork does not come cheaply. It costs you time—that means you pay for it with your life. It takes time to get to know people, to build relationships with them, to learn how you and they work together.

• Personal Development: The only way your team will reach its potential is if you reach your potential. That means today's ability is not enough. Or, to put it the way leadership expert Max DePree did: "We cannot become what we need to be by remaining what we are." That desire to keep striving, to keep getting better, is a key to your own ability, but it is also crucial for the betterment of the team. That is why UCLA's John Wooden, a great team leader and the greatest college basketball coach of all time, said, "It's what you learn after you know it all that counts."

• Unselfishness: People naturally look out for themselves. The question "What's in it for me?" is never far from their thoughts. But if a team is to reach its potential, its players must put the team's agenda ahead of their own. And if you give your best to the team, it will return more to you than you give, and together you will achieve more than you can on your own. Certainly there are other prices individuals must pay to be part of a team. You can probably list several specific ones you've paid to be on a team. The point is that people can choose to stand on the sidelines of life and try to do everything solo. Or they can get into the game by being part of a team. It's a trade-off between independence and interdependence. The rewards of teamwork can be great, but there is always a cost. You always have to give up to go up

FOUDNRY COATIN TECHNOLOGY

2017-08-05T04:10:00.000-07:00

Research in coatings for various applications such as aesthetics, corrosion protection, wear resistance, thermal barrier, self-cleaning, antifouling etc. have been very wide spread but not much is going on in the area of foundry coatings in recent times. The use of foundry coatings for moulds and cores during casting is very necessary as a means of achieving high quality surface finish of castings more especially in complex internal channels created by use of cores. This is despite the con-siderable advances that have taken place over the recent years in binder and sand technology giving the foundries greater opportunity to choose and control these basic foundry raw materials. Since casting surface finish de-pends largely on sand particle grading, it might be sup-posed that a proper selection of a particular grade of sand would be the only requirement to achieve the desired casting surface quality. However, there are other factors to be considered, such as the ability to vent off the gases produced during casting, economic use of a binder, non availability of sand with required grading, etc., these make the use of coatings the more practicable approach .

In filling a mould with liquid metal its surface is sub-jected to thermal, mechanical and physicochemical ac-tions. The oxidation products of the metal, reacting with the mould material, form low-melting materials such as silicates, which lubricate the grains of the quartz sand well. This promotes penetration of the metal into the in-ter-granular spaces and the formation of mechanical pick-up which is difficult to remove from the casting surface. Considering that the sand moulds and cores are highly porous, the production of castings in these materi-als without pick-up and other surface defects is possible only with protection of the surfaces of moulds and cores with refractory coatings. The fundamental requirements for the refractory coatings are minimum porosity, high refractoriness and reduction of the physicochemical reac-tion at the metal-coating interface (lubrication, solution, penetration). These refractory coatings are used to make better castings and to reduce costs. Castings sur-face quality is improved because the coating produces smoother metal surfaces, either by filling the spaces be-tween the sand grains or by providing, to the metal, a surface smoother than the mould surface itself. Further improvement from the coatings is due to the cleaner and better peel of sand at shakeout and elimination of certain defects such as metal penetration, veining, erosion, sand burn-in etc [3,4].

Controlling casting quality and increasing productivity are top priorities for foundries to become more competi-tive in a global casting market and coatings can help to provide the required remedy. Addressing the issue of mould/core moisture can lead to improvements in pro-ductivity and help keep foundries competitive. Identify-ing problems like poor mould/core density and moisture in the both core and mould is challenging, but advance- ment in coating technology enhances the engineering of refractory coatings as a quality-control tool to help iden-tify these issues. The presence of moisture can lead to a scrapped casting, but coatings that indicate when drying is complete can address this issue. Coating technologies that change colour offer visual confirmation that the coating is dry. This confirmation may also indicate poor sand compaction in a core or mould, as these areas will absorb more moisture from the coating and take longer time to dry. Therefore, a visually obvious colour change based on moisture content permits these new refractory coatings to act not only as a barrier between the metal and the mould or core but also as a quality diagnostic .

The objective of this paper is to collate as much as possible the significant works and results on foundry coatings in the past and to give insight to a novel tech-nology for the production of foundry coatings with greater potential towards improving the surface quality of castings from readily available raw materials at a cheaper cost. This paper provides a detailed understanding of the constitution of foundry coatings while providing alterna-tives to the foundry coating components depending on the metal to be cast and their properties and compatibility with sand properties such as grain size and grain size distribution and binder properties.

Groups of Foundry Coatings

Foundry coatings may be divided into two groups, those applied dry and those applied wet.

2.1. Coatings for Dry Application

For dry application, the most widely used is Plumbago. Other dry coatings used to a lesser extent include mica, white talc and wheat flour. These materials are either shaken or blown onto mould or core surfaces from open-mesh cloth bags. Plumbago is a finely ground blend of graphite containing 80% to 90% of particles that will pass through a 200-mesh (75 micron). The graphite may be amorphous (no definite crystal structure) or crystalline (having definite particle shape or flaky). Graphite will not melt at the highest foundry temperatures but its car-bon is driven off by oxidation at these temperatures de-pending on the air (containing oxygen) available at the metal-mould interface. Amorphous graphite oxidizes easier than does crystalline graphite. Plumbago is applied dry only on green sand moulds .

2.2. Coatings for Wet Application

Mould and core coatings for wet application are of two types, carbon-base and carbon-free coatings. Both types are sold in either powder or paste form. The adherence of the coating on the mould or core surface depends on the moisture in the sand. Carbon-based coatings may contain several types of graphite, coke, anthracite or any of the numerous combinations that can be made from these materials. Carbon-free coatings may contain silica, mica, zircon flour, magnesite, olivine, clays, talc or a combina-tion of these materials. Many coatings formulations con-tain both carbonaceous and non-carbonaceous raw mate-rials to take the advantage of the synergistic characteris-tics of both types. Foundry coatings for wet applica-tion are also classified into two, based on their carrier systems. Those employing an aqueous carrier and those in which organic solvent carriers are used. The former must be dried after application while the later are self-drying or can be ignited and dried by their own combustion. Both classes of coating make use of the re-fractory materials .

3. Components of a Coating (Coating

Materials)

A refractory coating on the mould or core should have the following characteristics:

Sufficient refractory properties to cope with the metal being poured

Good adhesion to the substrate to prevent spalling

Be permeable to minimize air entrapment

Be fast in drying

No tendency to blistering, cracking or scaling on dry-ing

Good suspension and remixing properties

Minimize core strength degradation

Provide adequate protection against metal penetration

Good stability in storage

Good covering power

Good application properties by the method chosen

Leveling well and minimizing runs and tear drops

For a coating to achieve these characteristics, the coating will consists of

Refractory filler

Liquid carrier

Suspension agents (Rheology control system)

Binder agents

Additives as shown in Figure 1

3.1. Refractory Filler (Filler Materials)

Refractory materials are substances or minerals that have high melting points and are difficult to fuse except at very high temperatures. They are processed at high tem-perature and/or intended for high temperature applica-tions. Refractoriness has been defined by Commit-tee C-8 of the American Society for Testing and Materi-als (ASTM) as “...the capability of maintaining the desired degree of chemical and physical identity at high temperatures and in the environment and conditions of use.” The melting temperature of refractory materials is an important characteristic showing the maximum tem-perature of use and represents fundamental point in phase diagrams used in high temperature chemistry, metallurgy, ceramics etc.

In coatings, refractory materials are dispersed in the binder and constitute the skeleton of the coating film. They increase the density, viscosity and hardness of the coating film and reduce the permeability.

There are characteristics other than resistance to high temperatures that refractory materials should exhibit. These include:

Suitable particle shape, particle size (PS) and particle size distribution (PSD),

Chemically inert with molten metal,

Not be readily wetted by molten metal,

Not contain volatile elements that produce gas on heating,

Have consistent cleanliness and pH

Be compatible with new chemical binders as they are developed The significance of particle shape, PS and PSD are elaborated below in the following paragraphs. The other factors are readily understood.

At a given refractory material loading, particle shape determines the mechanical properties of the coating ma-trix. The particle shape is usually described by a dimen-sionless parameter, the aspect ratio–this is the ratio be-tween the average diameter and average thickness of the particle. The higher the aspect ratio of the particle of re-fractory material, the higher the reinforcing effect on the coating matrix will be.The particle size distribution (PSD) of a refractory material is usually given as a cumulative curve, indicat-ing the amount per volume or weight of particles (%), which are smaller than a given size. PSD can be adjusted by grinding and classification. The coarsest particles act as points of highest stress concentration, where crack or fractures occur under loading. Impact strength is signifi-cantly improved by using finer particles .It is generally assumed that a sieve analysis sharply defines between the different sizes of particles compris-ing aggregate materials. According to [3], such is not the case. On any particular sieve one finds particles ranging from those just able to pass through the preceding sieve to those just unable to pass through to the following sieve. As a result of this lack of sharp differentiation between the particle sizes on adjacent sieves, it is difficult to sim-ply screen aggregate material and secure particles of uniform size on each of two successive sieves (Figure 2).

From a practical aspect, the refractory material should be available in large quantities at reasonable prices [8]. In foundry coatings, refractory materials determine the efficiency of the coating. The refractory filler may be either a single material or a blend of materials selected for specific applications. They make up 50% to 70% of the coating. Fillers are chosen for their particle size and shape, density, sintering point, melting point, thermal conductivity, thermal expansion and reactivity towards the metal being cast and the mould or core material on which it is applied These refractory materials in-clude Plumbago, silica, graphite, coke, anthracite, zircon flour, magnesite, Chalmette, olivine, clays, talc, chromite, alumina, mica.The material of which sand moulds and cores are made generally exert influence upon the surface quality of the castings formed from these moulds and cores. This is because they have a high degree of porosity to the extent that the pores tend to be filled with molten metal causing high surface roughness on the castings.

Therefore, with the application of refractory coatings on the surface of the moulds and cores that will be in contact with the molten metal, the refractory particles tend to fill these pores on drying, thereby creating a smooth inert surface on the moulds and cores. These re-fractory materials have different properties and are se-lected depending on the metal to be cast. The more common refractory materials are discussed below.

Silica flour is a commonly used refractory filler, par-ticularly in steel foundries. The silica flour should con-tain minimum 98% silica and not more than 1% moisture. The fusion point of silica flour is 1734°. At ap-proximately 650°C (1100°F), silica refractory filler has an expansion of 1.6%. Silica fillers are well known for use as pigments, reinforcing agents and the like.

Commercially available silica and other metals oxides are often derived from burning volatile metal halides with various fuels and oxidants. Silica filler has been produced by direct combustion of silicon powder as re-ported in [14]. Silica flour does not excessively increase viscosity [15]. However, it is reported in [16] that as the content of silica filler increased the coefficient of thermal expansion of the composite decreased while the viscosity increased.

Zircon flour is a highly refractory material and is primarily used for coatings in steel foundries. Good qual-ity zircon flour suitable for foundry work should contain minimum 64% zircon oxide (ZrO2), 30 to 35.5% silica and maximum of 0.5% TiO2 + Fe2O3. Refractory uses of zircon require low interstitial water content. This trans-lates into low loss on ignition. Excessive internal radia-tion damage to zircon crystals (metamict zircon) can cause an increase in the loss on ignition of a zircon product. The desire of the refractory market for a low loss on ignition implies that a low picocurie/gram re-quirement is placed on zircon products.

It has a specific gravity of about 4.5 and a pH value of the water-based coating of not more than 9.The melting temperature is 2727 ± 10°C . The high heat conductivity, about double that of silica, promotes quick formation of a solidified metal layer and helps in pro-ducing castings with a fine grained structure. Its higher density than that of silica prevents metal penetration .

Graphite refractory materials are most commonly used for coatings in iron foundries and for non-ferrous castings. Molten metal does not wet graphite and sand grains coated with graphite coatings resist metal penetra-tion. This is the reason why graphite, Plumbago and car-bon are usually used in mould and core coatings except those for steel.Mould and core coatings containing carbonaceous ingredients are not used for steel, particu-larly low-carbon steels. The reason for this is because steel is sensitive to the carbon content and if there is carbon pick-up, the properties of the steel will change. The graphite used is naturally flaky type, silvery white in appearance, of a fine powder form and free from gritty particles. Good quality graphite for foundry use should have ash content of about 12 to 15% maximum; volatile matter 3% maximum; and moisture content 1% maxi-mum. Graphite inclusion in mould and core coatings also improves stripping during shakeout. A highly useful, desirable, substantially non-porous, smooth, non-spalling mould surface can be produced on porous moulds by subjecting them to a treatment with a controlled amount of colloidal graphite suspended in a volatile carrier or vehicle followed by a drying after the treatment and fi-nally baking at a relatively high temperature. The mould surfaces prepared in this manner possess substantially no pores, at least those of a size which can be penetrated by molten metal. With the presence of pores which cannot be penetrated by molten metal it is considered to be sub-stantially non-porous. The treatment, it is believed, in-troduces colloidal graphite particles into the mould pores and the subsequent baking fixes or anchors them in such a way as to prevent removal unless the mould surface itself is worn or cut away

Olivine is orthosilicate of magnesium and iron (MgFe)O·SiO2 and it occurs as forsterite and fayalite. Its density, conductivity and refractoriness are higher than those of silica. Its fusion point is high—about 1800°C- and as such it is favoured for heavy sections of alloy steel casting. Its resistance to slag reaction makes it suitable for the casting of high manganese steels. Olivine refrac-tory material can also be used for the casting of non fer-rous castings of intricate nature Olivine is used in preference to silica sand to overcome the silicosis hazard (Silicosis is a form of respiratory disease caused by inhalation of silica dust, and is marked by inflammation in the upper lobes of the lungs).

Talc is a hydrous magnesium silicate mineral with the chemical formula (Mg3Si4O10·(OH)2) and the softest mineral on Mohr’s scale of hardness. Talc is widely used as a filler material .Talc Mohr’s hardness is 1 and density of 2.6 - 2.8 g/cm3. It is used in many industries because of its characteristics—low hardness, adhesion capability (surface coating), high melting temperature, chemical inertness, hydrophobic, organophilic, platy, low electrical and high thermal conductivity . The inert and lamellar platy natures of talc improve its cracking resistance, adhesion and barrier properties.

Talc is practically insoluble in water and weak acids and alkalis. Above 900°C, talc progressively loses its hydroxyl groups and above 1050°C, it recrystallizes into different forms of enstatite (anhydrous magnesium silicate). Talc’s melting point is at 1500°C

Mica is a plate-like crystalline aluminosilicate and has been widely used as reinforcing filler in polymer matrix due to its excellent mechanical, electrical and thermal properties as well as lower cost than carbon or glass fibres .Chemically they contain complex silicate of aluminium and alkalis with hydroxyl. They crystallize in monoclinic system. Some varieties may contain iron, magnesium, lithium. There are seven important mica minerals: Muscovite or potassium mica, H2KAl3(SiO4)3; Paragonite or sodium mica, H2NaAl3(SiO4)3; Lepidolite or lithium mica, K·Li·Al(OH, F)2Al(SiO4)3; Phlogopite or magnesium mica, H2KMg3Al(SiO4)3; Biotite or magne-sium iron mica, (H2K)(Mg, Fe)3Al(SiO4)3; Zinnwaldite or lithium iron mica, Li2K2Fe2Al4Si7O24; and Lepidome-lane or iron mica, (H, K)2(Fe, Al)4(SiO4)5. Muscovite is the commonest of all and whenever the word mica is used it is understood to mean muscovite. No other natu-ral substance has been found to possess the properties equal to those of mica. Of all the known varieties of mica only muscovite and phlogopite are of commercial im-portance. Muscovite finds the largest use while phlo- gopite has a limited application. On the other hand phlo- gopite is superior to muscovite in heat resistance. Mus-covite can withstand temperatures up to 700°C, and phlogopite up to about 1000°C. Phlogopite is, therefore, preferred where a high temperature is required .Mica can be used as refractory filler in foundry core and mould coatings to eliminate or reduce finning defect in castings because of its lamellar plate-like nature

Clays used for the manufacture of refractory fillers are the kaolinites. In the kaolinites there are equal numbers of silica and alumina sheets and equal numbers of silicon and aluminium atoms. The basic composition is Al2O3- 2SiO2·2H2O Kaolinite crystals are normally hex-agonal disks which are built up by laying double sheets of alumina octahedral and silica tetrahedral on top of one another Kaolin clay is the most extensively used particulate mineral in the filling of coating of paper .Since kaolin clay is fine and refractory and has found application in coating for papers, it also has poten-tial application in foundry coating technology.

Other filler materials and their properties are provided

Different filler materials and their functions in the ma-trix depending on their various particles sizes are pre-sented in Figure 3.

3.2. Liquid Carrier

The liquid career is the medium containing the coating constituents and also serves as the vehicle to transport the filler materials onto the sand substrate Therefore, the coatings are typically suspensions of high melting point refractories in a liquid carrier. Liquid carrier con-stitutes about 20 to 40% of the coating. After application, it is necessary to dry the coating to prevent gas formation when the hot metal is poured into the mould. The forma-tion of gases may cause casting defects. After the liquid carrier is removed by evaporation or combustion, a pro-tective refractory layer is deposited on the surface of the mould or core .This layer prevents or minimizes the penetration of molten metal into the sand, reduces or prevents "burn-on" and erosion of the sand, and generally improves the quality of a casting surface. However, there are many factors to consider with carrier selection, in-cluding: compatibility of carrier with sand binder and/or refractory, method of drying, flammability and “burning” characteristics; toxicity and odour; application; labour and floor space. The most commonly used carrier are water-based (aqueous) and spirit-based (organic solvent)

3.2.1. Aqueous-Based Carrier

In this class, water is used as the carrier. Water is cheap and readily available but drying in an oven is usually necessary to remove it before casting

Table 1. Other filler materials and their respective proper-ties [17]. Data	Chamotte	Chromite	Magnesite	Chrome- Magnesite
Availability	abundant	Good	Good	Good
Refractoriness℃ (approx.)	1780	1850	1850	1850
Thermal expansion (×1000 mm/m)	0.0052	0.007	0.014	0.012
Thermal conductivity (WK-1m-1)	6-9.5	9-15	20-30	13-20
Wettability with molten metal	No wetting	No wetting	No wetting	No wetting

Water is non flammable and non toxic. It has no flash point. Water is the safest of the carriers. From environmental view point, the use of water-based coatings is highly recommended. However, apart from requiring heat to dry water-coatings, complete drying of deep pockets in a reasonable time can be difficult. It has greater tendency for tears or runs compared to organic-based coatings. It reduces the tensile strength of urethane no-bakes, cold box and silicate sands. It increases the potential for core breakage. There is also possible degradation during core storage. Moreover, aqueous-based coatings can freeze

3.2.2. Organic Solvent-Based Carrier

Organic solvent-based or spirit-based coating usually contains isopropanol (isopropyl alcohol) as liquid carrier for coating constituents, and the coating is dried by ig-niting and burning off the isopropanol This is typi-cal of organic solvent-based carriers which also include methanol, ethanol, hydrocarbons and chlorinated hydro-carbons. They dry very fast. Isopropanol is recommended for use on large moulds and cores Isopropanol has good combustion characteristics with slow burning front and a moderate hot flame. This reduces the chance of over-heating the sand surface and subsequent problems of sand friability. Isopropanol is also technically accept-able because it is compatible with a wide range of sus-pension agents and resin binders also used in the formu-lation of these coatings. Most of the organic sol-vent-based carriers are referred to as air-drying carrier. These include carbon tetrachloride, methylenechloride, chloroethene and chloroform. They rely for efficiency on a rapid rate of evaporation which places them in a more hazardous category than isopropanol. They are also not versatile as isopropanol in the formation of foundry coatings. In many cases, they call for specialized forms of gelling media and resin binders The use of organic solvent-based coatings is threatened by environmental issues because they are toxic and flammable

3.3. Suspension Agents (The Rheology Control

System)

There is no difficulty in keeping solid particles in per-manent suspension in a liquid if both have the same spe-cific gravity. This is not the case with foundry sand coatings. The maintenance of solid particles in suspen-sion is achieved by addition of suspension agents. These agents provide the suspension system that prevents the filler particles from agglomerating and separating out during storage of the coating over extended periods. It ensures that the coating is homogeneous and ready for application with the minimum of agitation. It also con-trols the flow properties of the coating and is designed to suit the application method that is used The sus- pension agent makes up 1 to 5% of the coating.

When water is used as the carrier liquid, bentonite clay is used as a suspension agent. Bentonite swells and forms a gel when mixed with water. Time must be allowed for gelling to proceed to completion. Two kinds of bentonite are in common use, one linked with calcium and the other with sodium ions. As a suspension agent bentonites ini-tially of the sodium type are preferred. Calcium bentonite is converted to sodium bentonite by treatment with so-dium carbonate. This treatment affects the swelling power of the clay and makes control of the viscosity of the coat-ing unpredictable. Apart from the difficulties with quality control of the bentonite, it has the disadvantage of tending to induce shrinkage cracks in the coating when dried. In view of the drawbacks associated with bentonite, substi-tutes are found in polysaccharide and certain forms of carboxymethyl cellulose. Polysaccharides require special mixers, which few foundries possess, to obtain optimum suspension The cellulose type does not require this special mixers and do not induce shrinkage cracks as does dried bentonite as shown in Figure 4 below.

With organic solvent-based carrier systems, different suspension agents are used. Modified bentonite known also as organic bentonite or bentone will gel and increase the viscosity of organic liquids such as alcohols and sol- vents. Bentones result from a base exchange of the inor-ganic Ca and Na cation for an organic one which is qua-ternary ammonium. Examples of suitable suspension agent for organic solvent-based carrier are hydrogenated castor oil and quaternary alkyl ammonium montmorillo-nite gels

3.4. Binding Agents

Binding agents are various materials which act to hold the particles of refractories together and attach them to the sand surface. The quantity of binder required for this purpose increases a little as the particle size of the re-fractory decreases, thereby increasing the surface area for a given ratio in the coating. However, it makes up to 1 to 5% of the coating. It is important to determine the mini-mum quantity of the binding agent, because too little results in poor adhesion but, excess produces brittle coating which may crack on drying and spall off during casting. Furthermore, resins and similar organic binders evolve gas on heating. Thus, any undispersed binder col-lected in partially dried areas of moulds or cores will cause local concentration of gas generation. In this way, defects such as porosity and lapping can result. It is also worthy to note that most organic binders and many sus-pension agents used in water suspensions are subject to biological degradation. For longer storage of the coating, precautions must be taken to suppress these reactions. Such reactions do not occur with spirit-based coatings. Binders used for water suspensions include sulphite lye, various clays (bentonite and kaolin), dextrin, molas-ses, sugars, silica ester and resins (furan and phenol) soluble or miscible with water. For spirit-based suspen-sions, natural or synthetic resins are required. These in-clude furan, phenol, urea formaldehyde, phenol formal-dehyde, novolac and natural wood resins.

4. Coating Application Methods

Several variables dictate the choice of application method. Part geometry and size, appearance of the coating finish, and production rate, allinfluence the type of application method. Facility constraints will also determine the choice of application method. The configuration of the applica-tion equipment is dependent on space or climate. Systems can be manually or automatically controlled. Other sys-tems may require extra equipment, such as holding tanks or outside air supply to operate properly.

Similar application systems may operate at widely varying parameters. The viscosity of the coating material, the desired thickness of the final coating, and the com-plexity of the part will determine the best operating-parameters for the application method. Thus, part tem-peratures, dip times or number of coats are put into con-sideration.

One factor that is important to all application methods is the transfer efficiency of coating material onto the part. Transfer efficiency is the percentage of solid coating material used that actually deposited on the surface of the part. The amount of solvent in the coating material is irrelevant. The higher the transfer efficiency, the better, as more coating material adheres to the part and less is wasted. Transfer efficiency ranges from 25% to 40% for conventional spray systems to almost 100% for dip and powder coating methods. Much of the pollution and waste created from organic finishing operations can be mini-mized or eliminated by improving the transfer efficiency of the application system. If the transfer efficiency cannot be improved, pollution control technology and waste handling measures must be employed . The following are different methods of applying foundry coating on cores or moulds.

1) Brushing and swabbing

2) Spraying

3) Dip coating

4) Flow coating

THE PRICE MUST BE PAID BY EVERYONE

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2. The Price Must Be Paid All the Time

The Price Increases If the Team Wants to Improve, Change, or Keep Whining. Have you ever noticed how few back-to-back champions there are in sports? Or how few companies stay at the top of Forbes magazine's lists for a decade? Becoming a champion has a high price. But remaining on top costs even more. And improving upon your best is even more costly. The higher you are, the more you have to pay to make even small improvements. World-champion sprinters improve their times not by seconds, but by hundredths of a second. No one can move closer to his or her potential without paying in some way to get there. If you want to change professions, you have to get more education, additional work experience, or both. If you want to run a race at a faster pace, you must pay by training harder and smarter. If you want to increase earnings from your investments, you either put in more money or take greater risks. The same principle applies to teams. To improve, change, or keep winning, as a group the team must pay a price, and so must the individuals on it.

4. The Price Never Decreases

Most people who quit don't give up at the bottom of the mountain, they stop halfway up it. Nobody sets out with the purpose of losing. The problem is often a mistaken belief that a time will come when success will suddenly get cheaper. But life rarely works that way. When it comes to the Law of the Price Tag, I believe there are really only two kinds of teams who violate it: those who don't realize the price of success, and those who know the price but are not willing to pay it. No one can force a team member to have the will to succeed. Each member must decide in his or her own heart whether the goal is worth the price that must be paid. But every person ought to know what to expect to pay in order for a team to succeed. For that reason, I offer the following observations about the cost of being part of a winning team. To become team players, you and your teammates will have at least the following required of you .. .

THE SCOREBOARD

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Every "game" has its own rules

and its own definition of what it means to win. Some teams measure their success in points scored, others in profits. Still others may look at the number of people they serve. But no matter what the game is, there is always a scoreboard. And if a team is to accomplish its goals, it has to know where it stands. It has to look at itself in light of the scoreboard. Why is that so important? Because teams that succeed make adjustments in order to continually improve themselves and their situations.

For example, look at how a football team approaches a game. Before the competition starts, the team spends a tremendous amount of time planning. Players study hours of game film. They spend days figuring out what their opponent is likely to do, and decide the best way to win. They come up with a detailed game plan. As the game begins, the game plan is very important and the scoreboard means nothing. But as the game goes on, the game plan means less and less, and the scoreboard becomes more and more important. Why? Because the game is constantly changing. You see, the game plan tells you what you want to happen. But the scoreboard tells what is happening. No team can ignore the reality of its situation and win.

For any kind of team, the scoreboard is essential in the following ways:

1. The Scoreboard Is Essential to Understanding In sports, players, coaches, and fans understand the importance of the scoreboard. That's why it is so visible at every stadium, arena, and ball field. The scoreboard provides a snapshot of the game at any given time. Even if you arrive at a game halfway into it, you can look at the scoreboard and assess the situation. I' m often surprised by how many people outside sports try to succeed without a scoreboard. Some families operate their households without budgets, yet wonder why they are in debt. Some small business owners go year after year without tracking sales or creating a balance sheet, and wonder why they can't grow the business. Some pastors busy themselves with worthy activities, but never stop to measure whether they are reaching people or performing according to biblical standards.

2. The Scoreboard Is Essential to Evaluating

I believe that personal growth is one of the keys to success. That's why I've taught lessons on growth at conferences and in books for more than twenty years. One of the key principles I teach is this: Growth = Change. I know this sounds overly simple, but people sometimes lose sight of the fact that they cannot grow and remain the same at the same time. Most people are in a position that can be described by something coach Lou Holtz once said: "We aren't where we want to be; we aren't where we ought to be; but thank goodness we aren't where we used to be." But when it comes to growth, change alone is not enough. If you want to become better, you have to change in the right direction. You can do that only if you are able to evaluate yourself and your teammates. That is another reason for the scoreboard. It gives you continual feedback. Competing without a scoreboard is like bowling without pins. You may be working hard, but you don't really know how you're doing.

3. The Scoreboard Is Essential to Decision Making

Once you've evaluated your situation, you're ready to make decisions. In football, the quarterback uses information from the score board to decide which play to call. In baseball, the scoreboard helps the manager know when to bring in a relief pitcher. In basketball, it can be used to determine whether to call a time-out. That was the case at Disney. First, Eisner looked at the company to understand its overall position. Then he evaluated individual areas for their effectiveness. Only then was he able to make good decisions concerning how to get Disney back into the game.

4. The Scoreboard Is Essential to Adjusting

The higher the level you and your team are competing on, the smaller the adjustments required to achieve your best. But making key adjustments is the secret to winning, and the scoreboard helps you to see where those adjustments need to be made.

5. The Scoreboard Is Essential to Winning . In the end, nobody can win without the scoreboard. How do you know when the game is on the line without a scoreboard? How do you know when time is running out unless you check the scoreboard? How will you know if it's cruise time or crunch time unless you have the scoreboard as a measuring device? If your desire is to take a leisurely drive with some friends, then you don't need to worry about a thing. But if you're trying to win the Indy 500, then you and your team must know how you're doing! Some organizations see the scoreboard as a necessary evil. Others try to ignore it—something they cannot do for long and still do well in their profession. And some organizations make checking the scoreboard such an important part of their culture that they are continually able to recognize and seize opportunities that lead to huge successes.

THE LAW OF THE BENCH

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You may have heard the expression, "It's not over until the fat lady sings," or Yogi Berra's famous comment, "It ain't over 'til it's over." Would you believe that sometimes it is over before it's over? You can learn to identify such times if you know the Law of the Bench. Let me give you an example. One Saturday in September of 2000, I went to a football game with some friends: Kevin Small, the president of INJOY; Chris Goede, who used to play professional ball; and Steve Miller, my wonderful son-in-law. We were looking forward to an exciting game between the Georgia Tech Yellow Jackets and the Florida State Seminoles, even though FSU was a very strong favorite. There's a pretty good rivalry between all Georgia and Florida college teams, so the teams can get pretty pumped up. And on that day, we weren't disappointed. The teams were battling, and the score was close. Tech was playing its heart out. The Law of the Bench is true in any field, not just sports. You may be able to do some wonderful things with just a handful of top people, but if you want your team to do well over the long haul, you've got to build your bench. A great team with no bench eventually collapses. In sports, it's easy to identify which people are the starters and which make up the bench. But how do you identify them in other fields? I want to suggest the following definitions: Starters are frontline people who directly add value to the organization or who directly influence its course. The Bench is made up of the people who add value to the organization indirectly or who support the starters who do.

Everyone recognizes the importance of a team's starters. They are the ones who are most often in the spotlight. As a result, they get most of the credit. And while both groups are important, if one group is liable to be neglected or overlooked, it's usually the people on the bench. In fact, the people most likely to discount or discredit the contribution of the

bench may be the starters. Some key players enjoy reminding the substitutes that they are "riding the pine." But any starter who minimizes the contribution of the bench is self-centered, underestimates what it takes for a team to be a success, and doesn't understand that great teams have great depth.

Every human being has value, and every player on a team adds value to the team in some way. Those truths alone should be enough to make team members care about the bench players. But there are also more specific reasons to honor and develop the players who may not be considered "starters." Here are several:

1. Today's Bench Players May Be Tomorrow's Stars

Rare are the people who begin their careers as stars. And those who do sometimes find that their success is like that of some child actors: After a brief flash in the pan, they are never able to recapture the attention they got early on. Most successful people go through an apprenticeship or period of seasoning. Look at quarterback Joe Montana, who was inducted into the NFL Hall of Fame in 2000. He spent two years on the bench as a backup before being named the San Francisco Forty-niners' starter. And as he was breaking records and leading his team to numerous Super Bowls, the person who sat on the bench as a backup to him was Steve Young, another great quarterback. Some talented team members are recognized early for their great potential and are groomed to succeed. Others labor in obscurity for years, learning, growing, and gaining experience. Then after a decade of hard work, they become "overnight successes." With the way people like to move from job to job today—and even from career to career—good leaders should always keep their eyes open for emerging talent. Never be in a hurry to pigeonhole someone on your team as a nonstarter. Given the right encouragement, training, and opportunities, nearly anyone who has the desire has the potential to emerge someday as an impact player.

2. The Success of a Supporting Player Can Multiply the Success of a Starter

When every team member fulfills the role that best suits his or her talents, gifts, and experience and excels in that role, then the team really hums. It's the achievement of the whole team that makes the starters flourish, and it's the achievement of the starters that makes the team flourish. The whole team really is greater than the sum of its parts. Or, as John Wooden put it, "The main ingredient of stardom is the rest of the team."

3. There Are More Bench Players Than Starters

If you look at the roster of any successful team, you will see that the starters are always outnumbered by the other players on the team. In professional basketball, twelve people are on the team but only five start. Major-league baseball teams start nine, but carry forty players. In pro football, twenty-two people start on offense and defense, but teams

are allowed to have fifty-three players. (College teams often have more than one hundred!) You find similar situations in every field. In the entertainment industry, the actors are often known, but the hundreds of crew members it takes to make a movie aren't. In ministry, everyone recognizes the people up front during a worship service, but it takes scores of people working behind the scenes to bring that service together. For any politician or corporate executive or big-name fashion designer that you know about, there are hundreds of people working quietly in the background to make their work possible. Nobody can neglect the majority of the team and hope to be successful.

4. A Bench Player Correctly Placed Will at Times Be More Valuable than a Starter

I think if you asked most people how they would classify administrative assistants as team members, they would tell you that they consider them to be bench players, since their primary role is support. I would agree with that—although in some cases administrative people do have direct influence on an organization. Take for example my assistant, Linda Eggers. Over the years, Linda has done just about everything at INJOY. She has been the company's bookkeeper. She used to run our conferences. She did marketing and product development. She is a very talented person. I think Linda is capable of doing just about anything. But she has chosen to take a supporting role as my assistant. And in that position, she makes a huge impact. Today my company has more than two hundred employees. I respect and value all of them. But if I lost everything tomorrow and could keep only five or six persons with whom to start over from scratch, Linda would be one of the persons I would fight to keep. Her value as a support person makes her a starter.

5. A Strong Bench Gives the Leader More Options

When a team has no bench, the only option its leader has is moving the starters around to maximize their effectiveness. If a starter can't perform, the team is out of luck. When a team has a weak bench, then the leader has a few options, but they are often not very good. But when a team has a great bench, the options are almost endless. That's why someone like Bobby Bowden, the coach at FSU, was able to wear down Georgia Tech. If one of his players got hurt, he had someone to replace him. If his opponent changed defenses, he had offensive players in reserve to overcome the challenge. No matter what kind of situation he faced, with a strong bench he had options that would give the team a chance to win.

6. The Bench Is Usually Called upon at Critical Times for the Team When an army is in trouble, what does it do? It calls up the reserves. That's the way it is in every area of life. The time you need the bench isn't when things are going well. It's when things aren't. When the starter gets hurt and the game is in jeopardy, a substitute steps in. That person's effectiveness often determines the team's success. If your team is experiencing a tough time, then you know the importance of having a good bench. But if you are experiencing a smooth period, then now is time to develop your backup players. Build the bench today for the crisis you will face tomorrow.

GIVE ME A LEVER LONG ENOUGH.. . AND SINGLE-HANDED I CAN MOVE THE WORLD

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From a very early age, we are taught to break apart problems, to fragment the world. This apparently makes complex tasks and subjects more manageable, but we pay a hidden, enormous price. We can no longer see the consequences of our actions; we lose our intrinsic sense of connection to a larger whole. When we then try to "see the big picture," we try to reassemble the fragments in our minds, to list and organize all the pieces. But, as physicist David Bohm says, the task is futile—similar to trying to reassemble the fragments of a broken mirror to see a true reflection. Thus, after a while we give up trying to see the whole altogether.

The tools and ideas presented in this book are for destroying the illusion that the world is created of separate, unrelated forces. When we give up this illusion—we can then build "learning organizations," organizations where people continually expand their capacity to create the results they truly desire, where new and expansive patterns of thinking are nurtured, where collective aspiration is set free, and where people are continually learning how to learn together.

As Fortune magazine recently said, "Forget your tired old ideas about leadership. The most successful corporation of the 1990s will be something called a learning organization." "The ability to learn faster than your competitors," said Arie De Geus, head of planning for Royal Dutch/Shell, "may be the only sustainable competitive advantage." As the world becomes more interconnected and business becomes more complex and dynamic, work must become more "learningful." It is no longer sufficient to have one person learning for the organization, a Ford or a Sloan or a Watson. It's just not possible any longer to "figure it out" from the top, and have everyone else following the orders of the "grand strategist." The organizations that will truly excel in the future will be the organizations that discover how to tap people's commitment and capacity to learn at all levels in an organization.

Learning organizations are possible because, deep down, we are all learners. No one has to teach an infant to learn. In fact, no one has to teach infants anything. They are intrinsically inquisitive, masterful learners who learn to walk, speak, and pretty much run their households all on their own. Learning organizations are possible because not only is it our nature to learn but we love to learn. Most of us at one time or another have been part of a great "team," a group of people who functioned together in an extraordinary way— who trusted one another, who complemented each others' strengths and compensated for each others' limitations, who had common goals that were larger than individual goals, and who produced extraordinary results. I have met many people who have experienced this sort of profound teamwork—in sports, or in the performing arts, or in business. Many say that they have spent much of their life looking for that experience again. What they experienced was a learning organization The team that became great didn't start off great—it learned how to produce extraordinary results.

One could argue that the entire global business community is learning to learn together, becoming a learning community. Whereas once many industries were dominated by a single, undisputed leader —one IBM, one Kodak, one Procter & Gamble, one Xerox—today industries, especially in manufacturing, have dozens of excellent companies. American and European corporations are pulled forward by the example of the Japanese; the Japanese, in turn, are pulled by the Koreans and Europeans. Dramatic improvements take place in corporations in Italy, Australia, Singapore—and quickly become influential around the world.

There is also another, in some ways deeper, movement toward learning organizations, part of the evolution of industrial society. Material affluence for the majority has gradually shifted people's orientation toward work—from what Daniel Yankelovich called an "instrumental" view of work, where work was a means to an end, to a more "sacred" view, where people seek the "intrinsic" benefits of work.1 "Our grandfathers worked six days a week to earn what most of us now earn by Tuesday afternoon," says Bill O'Brien, CEO of Hanover Insurance. "The ferment in management will continue until we build organizations that are more consistent with man's higher aspirations beyond food, shelter and belonging." Moreover, many who share these values are now in leadership positions. I find a growing number of organizational leaders who, while still a minority, feel they are part of a profound evolution in the nature of work as a social institution. "Why can't we do good works at work?" asked Edward Simon, president of Herman Miller, recently.

"Business is the only institution that has a chance, as far as I can see, to fundamentally improve the injustice that exists in the world. But first, we will have to move through the barriers that are keeping us from being truly vision-led and capable of learning." Perhaps the most salient reason for building learning organizations is that we are only now starting to understand the capabilities such organizations must possess. For a long time, efforts to build learning organizations were like groping in the dark until the skills, areas of knowledge, and paths for development of such organizations became known. What fundamentally will distinguish learning organizations from traditional authoritarian "controlling organizations" will be the mastery of certain basic disciplines.

That is why the "disciplines of the learning organization" are vital.

DISCIPLINES OF THE LEARNING ORGANIZATION

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On a cold, clear morning in December 1903, at Kitty Hawk, North Carolina, the fragile aircraft of Wilbur and Orville Wright proved that powered flight was possible. Thus was the airplane invented; but it would take more than thirty years before commercial aviation could serve the general public. Engineers say that a new idea has been "invented" when it is proven to work in the laboratory. The idea becomes an "innovation" only when it can be replicated reliably on a meaningful scale at practical costs. If the idea is sufficiently important, such as the telephone, the digital computer, or commercial aircraft, it is called a "basic innovation," and it creates a new industry or transforms an existing industry. In these terms, learning organizations have been invented, but they have not yet been innovated.

In engineering, when an idea moves from an invention to an innovation, diverse "component technologies" come together. Emerging from isolated developments in separate fields of research, these components gradually form an "ensemble of technologies that are critical to each others' success. Until this ensemble forms, the idea, though possible in the laboratory, does not achieve its potential in practice.2 The Wright Brothers proved that powered flight was possible, but the McDonnell Douglas DC-3, introduced in 1935, ushered in the era of commercial air travel. The DC-3 was the first plane that supported itself economically as well as aerodynamically.

During those intervening thirty years (a typical time period for incubating basic innovations), myriad experiments with commercial flight had failed. Like early experiments with learning organizations, the early planes were not reliable and cost effective on an appropriate scale.

The DC-3, for the first time, brought together five critical component technologies that formed a successful ensemble. They were: the variable-pitch propeller, retractable landing gear, a type of lightweight molded body construction called "monocque," radial air-cooled engine, and wing flaps. To succeed, the DC-3 needed all five; four were not enough. One year earlier, the Boeing 247 was introduced with all of them except wing flaps. Lacking wing flaps, Boeing's engineers found that the plane was unstable on takeoff and landing and had to downsize the engine.

Today, I believe, five new "component technologies" are gradually converging to innovate learning organizations. Though developed separately, each will, I believe, prove critical to the others' success, just as occurs with any ensemble. Each provides a vital dimension in building organizations that can truly "learn," that can continually enhance their capacity to realize their highest aspirations:

Systems Thinking. A cloud masses, the sky darkens, leaves twist upward, and we know that it will rain. We also know that after the storm, the runoff will feed into groundwater miles away, and the sky will grow clear by tomorrow. All these events are distant in time and space, and yet they are all connected within the same pattern. Each has an influence on the rest, an influence that is usually hidden from view. You can only understand the system of a rainstorm by contemplating the whole, not any individual part of the pattern.

Business and other human endeavors are also systems. They, too, are bound by invisible fabrics of interrelated actions, which often take years to fully play out their effects on each other. Since we are part of that lacework ourselves, it's doubly hard to see the whole pattern of change. Instead, we tend to focus on snapshots of isolated parts of the system, and wonder why our deepest problems never seem to get solved. Systems thinking is a conceptual framework, a body of knowledge and tools that has been developed over the past fifty years, to make the full patterns clearer, and to help us see how to change them effectively. Though the tools are new, the underlying worldview is extremely intuitive; experiments with young children show that they learn systems thinking very quickly.

Personal Mastery. Mastery might suggest gaining dominance over people or things. But mastery can also mean a special level of proficiency. A master craftsman doesn't dominate pottery or weaving. People with a high level of personal mastery are able to consistently realize the results that matter most deeply to them— in effect, they approach their life as an artist would approach a work of art. They do that by becoming

committed to their own lifelong learning. Personal mastery is the discipline of continually clarifying and deepening our personal vision, of focusing our energies, of developing patience, and of seeing reality objectively. As such, it is an essential cornerstone of the learning organization—the learning organization's spiritual foundation. An organization's commitment to and capacity for learning can be no greater than that of its members. The roots of this discipline lie in both Eastern and Western spiritual traditions, and in secular traditions as well. But surprisingly few organizations encourage the growth of their people in this manner. This results in vast untapped resources: "People enter business as bright, well educated, high-energy people, full of energy and desire to make a difference," says Hanover's O'Brien. "By the time they are 30, a few are on the "fast track" and the rest 'put in their time' to do what matters to them on the weekend. They lose the commitment, the sense of mission, and the excitement with which they started their careers. We get damn little of their energy and almost none of their spirit." And surprisingly few adults work to rigorously develop their own personal mastery. When you ask most adults what they want from their lives, they often talk first about what they'd like to get rid of: "I'd like my mother-in-law to move out," they say, or "I'd like my back problems to clear up." The discipline of personal mastery, by contrast, starts with clarifying the things that really matter to us, of living our lives in the service of our highest aspirations. Here, I am most interested in the connections between personal learning and organizational learning, in the reciprocal commitments between individual and organization, and in the special spirit of an enterprise made up of learners.

Mental Models. "Mental models" are deeply ingrained assumptions, generalizations, or even pictures or images that influence how we understand the world and how we take action. Very often, we are not consciously aware of our mental models or the effects they have on our behavior. For example, we may notice that a co-worker dresses elegantly, and say to ourselves, "She's a country club person." About someone who dresses shabbily, we may feel, "He doesn't care about what others think." Mental models of what can or cannot be done in different management settings are no less deeply entrenched. Many insights into new markets or outmoded organizational practices fail to get put into practice because they conflict with powerful, tacit mental models.

Royal Dutch/Shell, one of the first large organizations to understand the advantages of accelerating organizational learning came to this realization when they discovered how pervasive was the influence of hidden mental models, especially those that become widely shared. Shell's extraordinary success in managing through the dramatic changes and unpredictability of the world oil business in the 1970s and 1980s came in large measure from learning how to surface and challenge manager's mental models. (In the

early 1970s Shell was the weakest of the big seven oil companies; by the late 1980s it was the strongest.) Arie de Geus, Shell's recently retired Coordinator of Group Planning, says that continuous adaptation and growth in a changing business environment depends on "institutional learning, which is the process whereby management teams change their shared mental models of the company, their markets, and their competitors. For this reason, we think of planning as learning and of corporate planning as institutional learning."

The discipline of working with mental models starts with turning the mirror inward; learning to unearth our internal pictures of the world, to bring them to the surface and hold them rigorously to scrutiny. It also includes the ability to carry on "learningful" conversations that balance inquiry and advocacy, where people expose their own thinking effectively and make that thinking open to the influence of others.

Culture oF Discipline

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*Bureaucracy

George Rathmann, cofounder of biotech company Amgen, help grow the struggling company into an entrepreneurial enterprise worth $3.2 billion and 6,400 employees. An investment of $7,000 in 1983 would have been worth over $1 million. George understood that the purpose of bureaucracy is to compensate for incompetence and lack of discipline ‐ a problem that largely goes away if you have the right people on the bus in the first place. Most companies build in their bureaucratic rules to manage the small percentage of wrong people, which in turn drives away the right people, which then increases the wrong people on the bus, which then increases the need for more bureaucracy. Rathmann understood an alternative existed: avoid bureaucracy and hierarchy and instead create a culture of discipline.

Set your objectives for the year in concrete, you can change your plans but never change what you measure yourself against.

*Discipline Action within the Three Circles

1. Build a culture around the idea of freedom and responsibility, within a framework.

The good‐to‐great companies built a consistent system with clear constraints, but they also gave people freedom and responsibility within the framework of that system. They hired self‐disciplined people who didn’t need managed, and then managed the system, not the people.

2. Fill that culture with self‐disciplined people who are willing to go to extreme lengths to fulfill their responsibility.

People in good‐to‐great companies became somewhat extreme in the fulfillment of their responsibilities, bordering in some cases on fanaticism. They will do whatever it takes to turn potential into reality – “Raising Your Cottage Cheese”

3. Don’t confuse a culture of discipline with a tyrannical disciplinarian.

The good‐to‐great companies had level 5 leaders who built an enduring culture of discipline, the unstained comparisons had level 4 leaders who personally disciplined the organization through sheer force.

4. Adhere with great consistency to the Hedgehog Concept, exercising an almost religious focus on the intersection of the three circles. Equally important, create a ‘stop doing list’ and systematically unplug anything extraneous.

The good‐to‐great companies followed a simple mantra: “Anything that does not fit with our Hedgehog Concept, we will not do. We will not launch unrelated business. We will not make unrelated acquisitions. We will not do unrelated joint ventures. If it doesn’t fit, we don’t do it. Period.”

*Start a ‘Stop Doing’ List – it is more important than a ‘To Do’ List

CONFRONT THE BRUTAL FACTS

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*Facts are better than dreams

When it came to making tough decisions the good‐to‐great companies infused the entire process with the brutal facts of reality. When your honest about your situation the solutions are generally self evident.

*Create a culture where people have an opportunity to be heard

Don’t focus on motivating people through the vision, get the right people on the bus and share with them the finding of the company. The best way to de‐motivate people is to hold out false hope.

*4 Basic principles in creating the culture

1. Lead with questions not answers

Use questions for one and one reason, to gain understanding. Don’t question to manipulate or place blame

2. Engage in dialog and debate, not coercion

Create intense dialog, don’t use discussions as a sham process to people buy in to a predetermined decision.

3. Conduct autopsies, without blame

When you conduct autopsies without blame, you go a long way toward creating a climate where the truth is heard

4. Build red flag mechanisms

Turn information into information that can’t be ignored

*Unwavering Faith amid the Brutal Facts

Darwin Smith of Kimberly‐Clark stated on taking on Proctor & Gamble, “We will never give up. We will never capitulate. It might take a long time, but we will find a way to prevail.”

*The Stockdale Paradox

“You must never lose faith that you will prevail in the end‐which you can never afford to lose‐with the disciple to confront the most brutal facts of your current reality, whatever they me be.” Admiral Jim Stockdale, prisoner of war 1965 – 1973, tortured over 20 times.

Retain faith that you will prevail in the end, regardless of the difficulties. And at the same time, confront the most brutal facts of your current reality, whatever they might be.

THE HEDGEHOG CONCEPT

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The Hedgehog Concept

The good to great companies are more like hedgehogs – simple, dowdy creatures that know “one big thing” and stick to it. Consistency

*The Hedgehog concept

Is a simple, crystalline concept that flows from deep understanding about the intersection of the following three circles:

1. What you can be the best at in the world, and what you can’t?

“They stick with what they understand and let their abilities, not their egos, determine what they attempt.” Warren Buffet about his $290 million investment in Wells Fargo

The hedgehog concept is not a goal, strategy, or intention; it is an understanding.

2. What drives your economic engine?

How to most effectively generate sustained and robust cash flow and profitability

3. What are you deeply passionate about?

Not to stimulate passion but to discover what makes you passionate

You want to find the intersection of what you can be best at, what drives your economic engine, and what you are passionate about. Don’t just settle for what you are good at; focusing solely on what you can potentially do better than any other organization is the only path to greatness.

Economic Insight – “If you could pick one and only one ratio –profit per x (or, in the social sector, cash flow per x) – to systematically increase over time, what x would have the greatest and most sustainable impact on your economic engine?”

Understanding Passion – Don’t try to inspire passion about what you are doing, do things that we can get passionate about.

*Circuit City’s Hedgehog Concept

To become the best at implementing the “4‐S” model (service, selection, savings, satisfaction) applied to big ticket consumer sales. Its distinction lay not in the “4‐S” model per se – but in the consistent, superior execution of the model. The cumulative value of $1 invested in Circuit City in 1972 would have been worth $311.64 in 1992!

THE FLYWHEEL AND THE DOOM LOOP

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*Flywheel Image

Imagine that your task is to rotate a massive 30 foot, 5000 pound disk. You push with great effort, you get the flywheel to inch forward and after a few hours you get the flywheel to complete one turn. You keep pushing, and the flywheel begins to move a bit faster, with continued great effort, you move it around a second time. You keep pushing in a consistent direction. Then three turns…four….five… the flywheel builds up speed…six turns…seven….eight…it builds momentum… 20…30…50…a hundred. Then at some point – breakthrough! The momentum of the whole thing works in your favor.

*Buildup and Breakthrough

The good‐to‐great companies came about by a cumulative process – step by step, similar to spinning the flywheel above. There was no single defining action, no one killer innovation, and no solitary lucky break. One Fannie Mae representative on the ‘magic moment’:

“There was no one magical event, no one turning point. It was a combination of things. More of an evolution, though the end results were dramatic.” The cumulative value of a $1 invested in Fannie Mae in 1984 would be worth $64.17 in 2000.

*The Flywheel Effect

Think of a circular model that continues to wrap around highlighted by four themes:

1. Accumulation of visible results

2. People line up, energized by results

3. Flywheel builds momentum

4. Steps forward, consistent with Hedgehog Concept

*The Doom Loop

Rather than accumulating momentum – turn by turn of the flywheel – the comparison companies tried to skip buildup and jump immediately to breakthrough. Then, with disappointing results, they’d lurch back and forth, failing to maintain a consistent direction.

Doom Loop Model:

1. No buildup; no accumulated momentum

2. Disappointing results

3. Reaction, without understanding

4. New direction, program leader, event, fad, or acquisition