 Welcome friends, in our previous lecture we have learnt about the history and the developments of the investment casting process. Now, let us continue this topic in this lecture also, before that let us review what we have learnt in our previous lecture. So, here these are the special features of investment casting process. What are the special features of investment casting process? It can produce very thin and most complex features. Second feature is it offers excellent surface finish. Most of the times no machining is required or very negligible machining is required. Next special feature it offers excellent dimensional accuracy. Finally, it can be used to cast all metals and alloys. Now these are the alloys covered in investment casting process, but before that if we see different manufacturing process or the casting process, what are the alloys that can be covered in these manufacturing process or the casting process? If we see the consider the die casting process, yes aluminum magnesium alloys can be cast using the die casting process or copper bronze brass can be cast using die casting process. What about the other alloys, ductile iron, stool steel, steel, titanium alloys, super alloys cannot be cast using die casting process. Next one if we consider the forging, yes tool steels, steels, stainless steel, aluminum magnesium alloys, copper bronze brass, titanium alloys, super alloys can be used for the forging, but ductile iron cannot be used for forging. If we consider the powder metallurgy process, tool steels, steels, stainless steel and titanium alloys can be manufactured using powder metallurgy process, but ductile iron, copper bronze brass and the super alloys cannot be manufactured using powder metallurgy process. Similarly, if we consider the sand casting process, ductile iron, tool steels, steels, stainless steel, aluminum magnesium alloys, copper bronze brass and super alloys can be manufactured using sand casting process, but titanium alloys cannot be manufactured using sand casting process. And finally, if we consider the weldments, steels, stainless steel, aluminum magnesium alloys, copper bronze brass, titanium alloys and super alloys can be welded, but ductile iron, tool steels cannot be welded. Now, let us come to the investment casting process, ductile iron can be manufactured using investment casting, tool steels, steels, stainless steel, aluminum magnesium alloys, copper bronze brass, titanium alloys and super alloys can be manufactured. If we see here, all the alloys can be manufactured using investment casting process. Virtually, there is no alloy which cannot be manufactured using investment casting process. So, that is the unique and greatest feature of the investment casting process. Now, in the previous lecture, we have seen the developments of the investment casting process during the 20th century. Now, these are the developments, initially the solid mould or the block mould investment casting was used, where the entire what say mould was filled with the ceramic material. Of course, wax was used as the pattern material and they used to pour the molten metal after draining of the wax. However, the ceramic material was replaced by the plaster mould. So, this used to give the better surface finish in the investment casting process. Later, mercast process was developed, where mercury was used as the pattern material, but there are certain problems associated with this mercast process. So, this is no more in use. Finally, ceramic shell investment casting was developed recently and this has gained what say importance all over the world. So, in the ceramic shell investment casting process, initially we make the pattern. Most of the times, it is made up of wax. Now, this wax pattern will be dipped in a ceramic slurry. A ceramic slurry will be prepared. Then after dipping this what say wax pattern inside the ceramic slurry, it will be taken out and a stucco coating will be given around the wax pattern. After this stucco coating is dried out, again it will be dipped inside the ceramic slurry. Likewise, this cycle will be repeated about say 5 to 7 times. Finally, a shell is created around the wax pattern. Now, let us concentrate on this ceramic shell investment casting process. So, we are already learning this. So, these are the major steps involved in the ceramic shell investment casting process. The first step is the wax injection. Wax will be injected into the pattern dye and it will be removed. Next one, several such patterns are assembled together here. So, that is the second step. Next one, as I told before, this wax assembly or the wax pattern will be dipped inside the ceramic slurry. It will be taken out. Then stucco will be what say sprinkled around the pattern. Then it will be dried out. Again, it will be dipped inside the ceramic slurry. Again, it will be taken out and stucco will be sprinkled around the pattern and it will be dried. So, this process, this cycle is repeated 5 to 7 times. Finally, a shell is created. Next one, after the shell is created, it will be dried. Then, de-vexing will be done. So, next one casting, next one knockout, next one cutoff, next one finishing and secondary operations. So, in the previous lecture, we have completed the wax injection. Now, let us see the pattern assembly. Hundreds of such patterns are produced in a single section and several such patterns are joined through a central tree to achieve economy. When we join several such patterns and make a single what say dipping, then there will be economy cost will be reduced. So, this is known as the pattern assembly. So, let us take an example case study pattern making for a gulf head. So, this is the gulf head looks like this, how it is manufactured? It is manufactured by investment casting process. Now, this is the typical wax injector. Now, hundreds or thousands of wax patterns are produced in a single section. So, these are all the wax patterns for the gulf head. Now, the wax patterns are assembled onto a tree. So, this is the common tree and here we can see 1, 2, 3, 4, 5, 6, 7. 7 patterns are assembled here with a single tree. The heads are joined to the tree via the gates. So, this is the assembled pattern. These trees are then transported to the slurry room. There the ceramic slurry will be there. This pattern assembly will be dipped inside the ceramic slurry. Next one shell building, how to do the shell building? How to make the ceramic shell? Before that, we need to learn the ingredients of the ceramic slurry. What is this ceramic slurry made up of? So, these are the three ingredients are there. One is the refractory powder or it is also known as the refractory floor. So, it comprises 60 to 80 percent. Next one, second ingredient is the liquid binder. So, it comprises 50 into 30 percent. Next one solid binder will be there, it will be 5 to 10 percent. Now, what are these refractory powders? The most commonly used refractory powders are first one is the zirconium silicate. It is also known as zircon floor. Second floor is refractory powder is fused silica. It is also known as silica floor. Third one is the fused aluminum oxide. It is also known as fused alumina. So, these are the ingredients of the refractory powder. Second ingredient is the liquid binder. Again, there are broadly mainly there are two types. One is the ethyl silicate, second type is the colloidal silica. So, anyone can be chosen and finally, a solid binder also will be used so, from 5 to 10 percent. So, these are the ingredients of the ceramic slurry in the investment casting process. Now, these there are various stages of slurry. First tip slurry is a fine texture that can easily get on to the details of the grooves and engraving graphics. So, generally 2, 3 ceramic slurries will be used not a single ceramic slurry. The first ceramic slurry is a very fine one means the ingredients are very fine one. So, that when the pattern is dipped inside this fine ceramic slurry it will be occupying and it will be flowing all around the what is the details of the pattern. Next one there will be another ceramic slurry will be there. So, the ingredients of the second ceramic slurry will be coarser than the first one. Next slurry coating is coarser than the first tips as the right it builds a thick ceramic shell around the wax tree. So, this is the second what is a ceramic slurry after the what is a pattern is dipped in the first ceramic slurry or the fine ceramic slurry now it is brought to the second one. So, this is coarser again it will be dipped and it will be taken out now a stucco will be sprinkled around the pattern then it will be dried out after it is dried out again it will be dipped inside the ceramic slurry. Now, the slurry has to dry between successive dipings that is very important temperature and humidity are carefully controlled. So, this is all about the shell building. Next one is the de-waxing prior to the pouring of the molten metal into the ceramic shell wax inside the shell has to be drained out completely and this process is known as de-waxing. Generally an autoclave is autoclave woven is used for the de-waxing process. So, inside this automatic what say autoclave woven high steam pressure at about 8 kg per square centimeters is injected into the sealed woven then what will happen the wax pattern will be melted the wax will be melted and it will be removed from the ceramic shell. Now let us see the what say operation or the construction details of a autoclave woven. Now, this is the schematic diagram of an autoclave woven. So, here we can see a steam is produced in the steam boiler now you see here there is a control now it goes to the accumulator here it will be accumulated and here it comes out and here there are again controls. So, from the accumulator steam comes to the autoclave chamber. So, here there is a chamber and here we can place the patterns here like this. So, this what say steam at a very high pressure comes and what say it will be injected into the autoclave. Now, because of this high temperature and because of the high pressure the wax pattern will be melting the wax that is inside the ceramic shell will be melting and it will be removed. Now, here there is wax and condensate recovery. So, it comes out the again there is a control valve you see when we open this control valve the water steam and the melted wax will be coming out that to wax again it will be what say refined it will be purified and again it will be used for making the pattern. So, this is the what say working principle of the autoclave woven. This one is the casting. Casting means pouring the molten metal into the ceramic shell. The ceramic moulds must be heated up before molten steel can be poured into them. So, before we pour the molten metal these shells must be heated steel is being poured from the crucible into the iron what say mould into the iron head mould. You see here after the shell is filled with the liquid steel it must be set aside to cool down. It must be kept aside. So, it takes time for cooling freshly poured ceramic shells generate a lot of ambient heat. Now, we have poured the molten metal into the ceramic shell it after some time the metal will be cooling and it will be solidifying. Now, the next process is the knockout knockout means breaking that shell and removing the casting outside. A motorized chisel is used to break the ceramic shell away from the cast part. Sometimes it is broken manually, but most of the times a motorized chisel is used to break the ceramic shell to take the what say casting outside. Now, here we can see here the metal tray is sandblasted to remove any remaining ceramic shell. After we break the ceramic shell of course, we take the casting outside, but still small traces of ceramic shell will be adhering to the casting. So, these traces of ceramic shell are to be removed from the casting that is why we are using a sandblasting system. So, here is you can see there is a sandblasting what say chamber is there sandblasting chamber the castings will be kept inside then sand will be blasted on the casting. So, if there are any traces of the what say ceramic shell they will be removed because of the sandblasting. Next one is the cut off what is this cut off the castings are cut at the gates which leaves the excess material on the gate areas it needs to be polished previously we have seen that when we make the wax patterns several such wax patterns are assembled together. Now, after we get the casting we have to separate the individual castings so that is the cut off. So, for that most of the times a grinding wheel is used for separating the castings from the assembled tree. Next one is the finishing and secondary operations the castings are heat treated to normalize the metal. So, that is one of the finishing operations. Next one heat treatment ovens can vary in size appropriate surface finish is polished on the parts mirror and satin finishes are the most common these days we have to obtain the appropriate surface finish on the castings. So, that also is a part of the secondary operations finishing and secondary operations you can see here again here the heads are cleaned for final cosmetic preparations they are cleaned so that there will be a very good and pleasant appearance. The final production step involves adding cosmetic paint also that also is a part of the secondary operations. Now, the final product will be free from flaws and visually appealing so this is the final part of the casting golf head. Now, let us see the alloys covered in the investment casting process now in fact this is the special feature of the investment casting process most of the alloys can be cast in fact virtually all the alloys can be cast using investment casting process. The range of alloys covers virtually the complete spectrum of alloys in engineering use it includes the non ferrous alloys steels nickel and cobalt base alloys ductile or spheroidal graphite irons titanium alloys and a number of special purpose materials there is no material which cannot be cast using investment casting process. So, these are the common investment cast alloys one is the ductile iron carbon steels tool steels stainless steels aluminum magnesium alloys copper bronze and braces titanium alloys and super alloys. So, these are the common cast alloys in fact any alloy can be cast using investment casting process. Now, let us see the common applications of these what say investment cast alloys first we will see the investment casting of ductile iron. Ductile iron is manufactured by an alloying process in which the graphite flakes of grey iron are converted into spheroidal or spherical nodules generally what say in the cast iron the graphite is appearing in the form of the flakes this is known as the grey cast iron. But this will be modified in the coming to the ductile iron these graphite flakes are modified and a treatment is given such that these graphite flakes are converted into spheroidal or spheroidal nodules that is why ductile iron is known as the spheroidal cast iron or it is also known as the nodular cast iron. Now, ductile cast iron is widely used in the investment casting process ductile iron when used in investment casting process offers the potential to manufacture complex parts with high dimensional accuracy applications of ductile cast iron in investment casting process defense components can be produced automotive components can be produced pulp pump and valve components can be produced and several general engineering components can be produced using investment casting process. Now, let us see an example this is the inlet plate used in a gas compressor made up of ductile iron and it is made by investment casting process. Now, now you can see here some more components pump and valve components made up of ductile cast iron and it is made these are made by the investment casting process. We will cast it part made up of ostempered ductile iron by investment casting process. Next one let us see the investment casting of carbon steels carbon steel investment castings are commonly used in a broad spectrum of industries. Investment applications locks and internal lock mechanisms lock bodies and keys door handles and door closure units mining applications military and firearms and finally transportation what say parts the all these are manufactured using investment casting process. Now, here we can see these are the hard what say hardware and lock components made up of what say carbon steel and these are produced by investment casting process. So, these components require very good surface finish and excellent dimensional accuracy and further these components possess what say complex features. So, these carbon steels and these carbon steel components are produced by the investment casting process and we can see here military and firearm castings these are made up of carbon steel and these are produced by investment casting process very fine surface finish. Next one let us see the investment casting of tool steels tool steels are referred to a variety of alloy steels that are particularly used for making different tools. We use the cutting tools the lathe tool the milling cutter the planning cutter all these tools are produced by the investment casting process. And here for example, we can see tool steel parts produced by investment casting process. So, these are the what say tool steels produced by investment casting process. Next one this is a standard milling cutter produced by the investment casting process. Next one let us see the investment casting of stainless steels stainless steel investments castings can be produced to a mirror finish for the ultimate in a corrosion resistance even in what say salty marine conditions. Among the stainless steels austenitic blades are commonly in use for most of the investment casting applications. Here we can see this is the pelton wheel blades made up of austenite stainless steel and produced by investment casting process. This is a revolver frame made up of martensitic stainless steel produced by investment casting process. Now, this is a duplex stainless steel corrosion resistant wall produced by investment casting process. Now, let us see the investment casting of aluminum and magnesium alloys. Here we can see the aerospace component. So, these are produced by the investment casting process and here we can see in this component there are several thin fins. You can see extremely what say very good surface finish is required and the fins are very what say thin and complex features are there and these what say parts are produced by the investment casting process. Next one aluminum automotive component here we can see again this is produced by the investment casting process again you can see here this is another component again produced by the investment casting process. Investment casting of copper, bronze and brass and here we can see this is a copper casting thin blades are there. So, these are produced by the investment casting process. So, this is the locomotive accessory again it is produced by the investment casting process. Now, let us say the investment casting of titanium alloys jet engine diffuser made up of titanium. Here you can see a component with what say complex features and thin sections and which requires very good surface finish and it is produced by the this titanium alloy component is produced by the investment casting process. A titanium Formula 1 race car suspension path again it has got thin sections and complex sections again it is produced by the investment casting process. Next one finally, let us see the investment casting of super alloys this is the turbine impeller you can see the what say a complexity of these blades very thin blades and they have got the complex what say features and this titanium impeller is manufactured by investment casting process. Now, let us see the rapid prototyping in investment casting process recently this rapid prototyping has emerged as a what say means for producing the patterns. The most what say tough what say phase of the investment casting is the producing the pattern. Once we produce the pattern yes we can dip it inside the cement shell and yes we can build this what say cement shell and we can produce the casting, but producing the pattern is very difficult. So, that is why rapid prototyping has emerged to produce the patterns. Now, let us see the important rapid prototyping process one is the stereolithography it is also known as SLA. Next one selective laser sintering SLS, next one 3D printing, next one used deposition modeling FDM finally bio plotter. So, these are only a few important rapid prototyping process in fact there are more process. Now let us see these what say process and their principles briefly first one let us see the stereolithography. Now, here there is a liquid resin and here is the laser system and yes here there is a scanner this laser will be falling on the liquid resin. So, this is a photopolymer wherever this laser forms there it will be the liquid resin will be cured and it will become solid likewise wherever we want to what say have a what say solid body there the laser will be scanned. So, finally, we get the what say required component. So, this is the basic principle. So, this is the what exactly happens. So, this is a vat means like a tank and inside there is photopolymer will be there. So, what is the speciality of the photopolymer when what is a light at the laser falls on this photopolymer it will be cured it will become a solid particle. Now, here we can see this is the support this is this is the stand and here we can see laser it is connected to the laser and laser beam will be falling here initially the first layer it is the what say jet stage will be moved up. Now, this is the stand this is the stand stage the stage will be at the top here somewhere here. Now, it will be what say cured layer by layer the laser scanning system will be curing the first layer then it comes down means the solidified layer will be going inside the photopolymer. Now, again photopolymer will be covering the solidified layer again the laser will be curing the second layer then it comes down again the polymer fills that what say cured layer again the laser will be curing the third one. So, gradually the what say stage will be coming down and the laser system will be curing one layer after another layer likewise the entire solid is what say cured like this of course, these are the supports. So, this is the principle of the stereolithography next one is the selective laser sintering. So, this is similar to the previous one stereolithography, but here in the case of the selective lasering sintering in the previous case the liquid what say polymer is used and here powder is used that is the primary difference and here also laser scanning system will be there. So, what is the principle here yes there are two stages here right one stage for the powder and another stage for the pattern. Now, initially yes the it moves little up the powder what stage and there will be a roller this roller will be rolling and it spreads this powder evenly in this what say stage. Now, the scanning system will come and it will be curing the first layer once it cures the first layer this jet stage will be coming down one step it comes down again it moves by this powder stage will be moving one step upwards again the roller will be moving and it moves the what say powder even it distributes evenly here again the scanning system will come and it will be curing the second layer again then the this stage will come down that the jet stage will come down one step again this goes up again roller will go and it will distribute the powder evenly above this stage again the scanning system will cure the third layer likewise it is similar to the stereolithography, but here it is the powder is used for making the pattern finally, the whole what say pattern is created like this. So, this is the required pattern next process is the 3D printing this is also similar to the previous one the selective laser is sintering, but in the in this case of the selective laser is sintering for curing purpose we were using what say laser system, but here laser system is replaced by the liquid adhesive same principle yes there are two stages are there this is the powder what say stage. So, every time this powder stage will be moving up one step upwards and here there is a roller this roller will be rolling and the powder will be distributed above this jet stage evenly. Now, this liquid adhesive will be released and wherever again it is connected to the computer in which there is a model is created now wherever we want to cure right here the liquid adhesive will be distributed now it will be hardened now it comes down by one step and the powder stage will be moving up by one step again the roller will be there roller will be rolling and it takes the powder and it distributes the powder above the jet stage evenly again with the help of the what say scanning system the liquid adhesive will be distributed over the second layer and it will be hardened again it comes down and the powder stage will be moving one step above likewise the principle is similar to the selective lasering system sintering. Next one is the POZ deposition modeling and here we can see this is the support materials pool and this is the build materials pool two spools will be there. So, this will be moving like this and here we can see this is the extrusion nozzle will be there now this building build materials pool will be passing through the extrusion nozzle yes then it will be spreading and here it will be spread. So, again it will be connected to the computer now the liquefier head moves in x and y direction you see here it will be moving in the x and y direction means it will be making a a thin sheet at a time then it will be coming down the stage will be coming down again it will be making a thin sheet because it is moving in the x y direction in the next stage it will be making another sheet it will be curing another sheet likewise finally, these are the ice patterns ice patterns are found to be what is a very effective in the investment casting process and here we can see these are all the ice patterns. Now, what are the advantages of ice patterns first advantage is the better surface finish very good surface finishes obtained using the ice patterns. Next one elimination of cracks in the shell during the pattern removal most of the times when we use the wax pattern yes what we do yes we put it inside the de-waxing chamber or the autoclave woven what will happen when we try to heat the what say ceramic shell in which there is wax first wax will be expanding because of that the ceramic shell will be cracking. So, these are the drawbacks of using the wax as the pattern material, but here the cracking of the ceramic shell does not arise why yes if we heat the ceramic shell inside the woven ice will be there. So, ice will be when we raise the what say temperature because of the abnormal expansion of the water what will happen the volume will be coming down till what say 4 degree centigrade because the volume is coming down the shell would not be cracking. So, that is the greatest advantage of using the ice patterns. Next one pattern material water or ice is not expensive if it is the wax pattern means we need to purchase the wax not only wax we need to find what say make a blend of the wax. So, these are expensive, but ice pattern what is the raw material water it is not expensive again this is a what say a good advantage of using ice patterns. Friends in this lecture in these two lectures we have seen the developments of this process during the 20th century and we have seen solid mould or the block mould investment casting process. Next one we have learnt the plaster moulding investment casting process next we have seen the mercast process in which the pattern material is the mercury finally, the last one is the ceramic shell investment casting process. So, these are the four developments of the investment casting process we have studied and in the ceramic shell investment casting process. So, these are the different steps we have seen wax injection pattern assembly shell building de waxing casting knockout cut off finishing and secondary operations are the steps involved in the ceramic shell investment casting process and we have completed this and we have seen that it can produce the very thin and most complex features and it offers the excellent surface finish it offers the excellent dimensional accuracy and it can be used to cast all the metals and alloys. And we have also seen that among several manufacturing and casting process investment casting has the unique what say specialty of covering all the alloys virtually all the alloys most of all the alloys can be cast using investment casting process. So, with this we are completing the investment casting process and in the next lecture we will be learning about the continuous casting process until then goodbye and thank you.