 Welcome friends, in the previous lecture we have learnt about different types of die casting process. We have seen that die casting process is broadly classified into two types. One is the gravity die casting and another one is the pressure die casting. In the gravity die casting there will be two metallic dies will be there and the molten metal enters into these dies by virtue of gravity. Whereas in the case of the pressure die casting again there will be two metallic dies will be there and the molten metal enters into the metallic dies because we apply some external pressure. So, that is the primary difference between the gravity die casting and the pressure die casting. Again the pressure die casting is classified into two types. One is the cold chamber pressure die casting and another one is the hot chamber pressure die casting. In the case of the cold chamber pressure die casting the furnace where we melt the metal is away from the die casting machine. It is not the part of the machine. Whereas in the case of the hot chamber pressure die casting machine the furnace where we melt the metal is a part of the machine. It is an integral part of the die casting machine. So, that is the difference between the cold chamber pressure die casting machine and also the hot chamber pressure die casting process. Now, in this lecture we will see the recent advancements in the die casting process. So, one of the recent advancements in the die casting process is the semi solid metal casting process. What is this semi solid metal casting process? Metal shaping processes at various temperature we will see first. If we see the liquid casting shaping is carried out above the liquidous temperature. No doubt if we are making a casting we melt the metal above the melting point or above the liquidous temperature then we pour the molten metal into the mould cavity. So, that is the liquid casting. Again so, there is another metal shaping process that is the forging rolling extrusion. So, all these constitute the forming process. So, here how we get the required shape? We get the required shape below the solid temperature. Now, here we can see the difference between the what is the semi solid metal casting and the other process. Here shaping is carried out between solidus and liquidus temperatures. We want heat the metal above the liquidus temperature. We want cool down the what is the metal below the solidus temperature. This shaping is carried out between the solidus and liquidus temperatures. So, that is the special about semi solid metal casting process or semi solid what is a forging and here we can see the liquid casting and here in this what say this is the phase diagram of aluminum and silicon and here we can see this is the liquidus temperature and this is the solidus temperature and here we can see this is the mixture of liquid and solid. Now, if it is the liquid casting, the casting is carried out above the liquidus temperature. So, this is the liquidus temperature. Now, let us see the forging rolling and extrusion this forming process. Now, I have already told. So, this is the liquidus temperature. Now, this is the solidus temperature. Now, here the forging and these and other forming process are carried out below the solidus temperature. So, that is about the forging and other forming process. Now, let us see the semi solid casting. Now, the most interesting feature of the semi solid casting is that the shaping is carried out between liquidus temperature and the solidus temperature. This is the liquidus temperature and this is the solidus temperature. Now, what are the features of semi solid metal casting? Semi solid metal casting is a near net shape variant of the die casting process. Semi solid metal casting is done at a temperature that puts the metal between its liquidus and solidus temperatures. Ideally, the metal should be 30 to 65 percent solid means it is not totally solid, it is not totally liquid. The process combines the advantage of casting and forging. The advantage of casting is that we get the required shape very easily because we melt the metal and we pour it into what is a mould. So, getting the required shape is very easy in the case of the casting, but the mechanical properties may not be very good. Besides this, there will be other problems like shrinkage cavities and so on. Now, in the case of the forging, applying the pressure or what is a causing deformation to the raw component is very difficult because extensive pressure is required, but we get very good properties. Now, we are mixing these two. We are taking the advantage of casting and we are also taking the advantage of forging. So, the process combines the advantages of casting and forging. The process is used with nonferrous metals such as aluminum, copper and magnesium. So, this is all about the semi solid metal casting. So, what is a deformation is carried out between the liquidus temperature and the solidus temperature and we get the advantages of casting and also the forging. We get better mechanical properties and this kind of shrinkage what is a defects are not likely to arise in the case of the semi solid metal casting process. Now, what are the types of semi solid metal casting process? One is the thixo casting, another one is the ryo casting, another one is the thixo molding and finally, the sima process. Now, we will see all these one by one. First we will see the thixo casting process. What is this thixo casting? Thixo casting utilizes a precast billet. We have to buy this billet in the market and it is precast under certain what is a controlled conditions under certain controlled environment. The billet has a non dendritic microstructure. You see this, this is very important. It has a non dendritic microstructure that is normally produced by vigorously stirring the melt as the bar is being cast. As we are getting this bar, it is it is rigorously stirred. Now, we buy this billet and we bring it and we have to cut it into pieces or to the required what is a quantity we have to cut. Then induction heating is normally used to reheat the billets to the semi solid temperature range. Now, after cutting these billets, we have to heat it to the semi solid temperature range means above the solid temperature but below the liquidous temperature. To a such an extent, we have to reheat this billet. Now, we have to put these billets into the cold chamber machine's die. There will be two, what say dies will be there set of dies. We have to put these what say reheated billets between these two dies. Now, cold chamber die casting machine applies external pressure on these dies and this it will be what say formed, it will be deformed. Cold chamber die casting machines are used to inject the semi solid material into the hardened hardened steel dies. Now, once we apply pressure on the dies, so it will be squeezed between these two dies and it what say preheated and reheated billet will be taking the shape of the cavity between the two dies. Now, this is what we can see diagrammatically. So, these are the what say special billets, precast billets. So, these are available in the market which are manufactured without under certain what say special conditions. It has got the non dendritic microstructure. Now, we will be cutting this saw to the required length and also to the required quantity we will cut them. Next one, we will put these what say cut pieces into a furnace. That means we are reheating them. We will reheat them above the solidest temperature, but below the liquidest temperature. Now, these what say reheated slugs are being transferred into the cold chamber die casting machine. We can see here. So, these are the dies. So, these will be kept inside these two dies. Now, pressure will be applied between these two dies and this what say slug which is reheated will be squeezed between the two dies and the slug will be taking the shape of the cavity which is available between the two dies. Now, sometimes some scrap will be there. This scrap cannot be reused. We have to sell out that scrap. Now, these are the advantages of thick saw casting. Thick saw casting has the ability to produce extremely high quality components due to the product consistency. So, this is the advantage of thick saw casting. Now, it has got the disadvantages and the drawbacks as well. What are they? This process is expensive due to the special billets that must be used. So, these billets are what say manufactured under special environment and so that some special what say properties are induced. So, these we have to buy from the market that is how the process becomes expensive. Only a limited number of alloys can be cast using this method. Now, as I have already told scrap sometimes we get the scrap. This scrap cannot be used directly. Again we have to sell. Again those people will make the what say precast billet under special conditions. Again they will sell it. So, that way scrap cannot be directly used. So, we have completed the thick saw casting. Next we will see the reocasting. What is this reocasting? Reocasting involves preparation of a semi-solid what say manufacturing slurry directly from the liquid alloy. The alloy is cold into a semi-solid state with the desired solid fraction and then is introduced into a dye with no any intermediate solidification steps. Semi-solid slurry with non-dendritic solid particles is produced from a fully liquid regular alloy. So, here we are not buying a what say precast billet from outside. Here we are making a slurry so that the component will have the required properties. The semi-solid slurry with non-dendritic solid particles. Again here we are getting the non-dendritic what say solid particles. So, when once this casting has the non-dendritic what say structure the properties will be good. So, such a what say component is produced from a fully liquid regular alloy and here we can see this diagrammatically. First we have to buy the ingot. So, this ingot is not a expensive as expensive as the billet which we buy in the previous process. Now, this we put it inside the what say furnace you can see here. Now you see here and in this what say we are what say stirring finally, it will be transferred to the die casting machine cold chamber die casting machine. There external pressure will be applied between these two dies and the slurry will be injected into the cavity which is available between the two dies. Sometimes we get the scrap is no need to what say what say discard that scrap again that scrap can be put inside the what say furnace again from that scrap we can get the slurry. So, that is the Rio casting. Now, what are the advantages of Rio casting process? No need to buy the precast billets as in the case of the Tixo casting. So, because we are buying the precast billets in the Tixo casting process the process becomes expensive. So, such things such thing would not arise here in the case of the Rio casting. Scrap can be reused immediately immediately if there is any scrap again it can be what say kept inside the furnace and we can get the required slurry. Now, what are the drawbacks of Rio casting obtaining the correct solid fraction is difficult. We have to control the temperature between the liquid temperature and the solid temperature we have to get the required solid fraction. So, that requires skill. So, skilled workers are required. Next one Tixo molding what is this Tixo molding? Tixo molding is used for magnesium alloys this can be used only for magnesium alloys. It uses a machine similar to injection molding generally this injection molding is used for producing plastic components. So, a similar machine is used for Tixo molding. Now, what is done inside this what say injection molding machine magnesium alloy chips initially we have to make magnesium alloy chips. So, these chips are fed into the back end of heated barrel at room temperature. Now, this barrel is maintained under argon atmosphere to prevent oxidation because magnesium readily what say reacts with oxygen. So, we have to prevent that for that purpose we use the argon atmosphere. Now, we are what say feeding these magnesium alloy chips to the back end of the heated barrel inside the injection molding machine. Now, there will be a screw in that. So, as this screw rotates what happens it provides necessary shearing force to generate globular structure needed for semi solid casting. So, there will be a screw as the screw is rotating these chips will be trapped inside the screw and they undergo shearing because of that we get the globular structure for the semi solid casting. Once enough slurry has developed the screw moves forward to inject the slurry into the steel type and here we can see diagrammatically. So, this is the what say a machine which is what say very much what say close to the injection molding machine which is used in the plastic manufacture of the plastic components and what is this machine it has a barrel you see this is a barrel outside barrel. Now, inside there is a screw it rotates and this is connected to a motor you see here here it is connected to a motor. And here there is a feeding hopper. So, there is a hopper will be there to feed the what say magnesium alloy chips here we feed the magnesium alloy chips. Now, you see here there is a argon atmosphere. So, so that there would not be any oxidation of the magnesium alloy. Now, this there is a heating what say system for this barrel this will be heated up. Now, here we can see these are the two dies this is one die and this is one die. Now, the screw will be rotating as the motor is rotating the screw will be rotating. Now, we what say feed the what say magnesium alloy chips into this hopper and they will be going inside the barrel as the screw is rotating the what say chips undergo shearing and finally, a slurry is formed and because it is heated you see it will be heated between 560 to 630 degrees centigrade. As the screw further rotates what will happen the slurry will be injected between the two dies there it solidifies once the slurry solidifies the dies will be withdrawn and the component will be taken out. Again the dies will be closed again the what say screw rotates the slurry will be injected into the two dies. So, this is the simple principle of thixomolding. Next one SEMA process what is this SEMA process in SEMA process the cast alloy is first hot work and then cold work to the desired degree of deformation you see first it is hot work means above the recrystallization temperature then it is cold work means deformation under the below the recrystallization temperature then the material is then heated between the solidus and liquidus temperatures after isothermal holding for about 15 to 20 minutes the semi solid slurry is cast or it injected between the two dies. So, this is the what say basic principle of the SEMA process. Now, what is the scientific understanding high angle grain boundaries induced by plastic deformation and recrystallization will be wetted by liquid metal at this semi solid temperature resulting a fine and globular structure. So, this is the scientific understanding this is the scientific principle behind the SEMA process. This method is limited in size to bar diameters smaller than 37 millimeters because of this only smaller parts can be cast. So, that is the limitation of this process only smaller components can be cast. Now, here we can see this process diagrammatically now this is the liquidus temperature and this is the solidus temperature and this is the recrystallization temperature and this is the room temperature. Now, you see here initially it is in the molten state now then it what is happening it is what say deformation is taking place. So, here it is between the liquidus temperature and solidus temperature and below the solidus temperature also there is deformation after that what is happening deformation extrude and quench between the room temperature and the solidus temperature it is what say extruded and it is quenched. So, this what say process will be repeated finally, it will be injected into the 2 dies of the die casting machine between the solidus temperature and liquidus temperature. So, this is the temperature where it will be injected between the 2 dies how is this temperature you see this temperature. So, this is the SSM form temperature. So, this is between the liquidus and solidus temperatures. Now, let us see the advantages of semi solid metal casting process. Complex parts are produced with near net shape very complex parts can be produced near net shape means almost no machining or negligible machining is required. Porosity free castings it is a very good advantage in the case of the castings. So, because of the solidification above say we pour the what say melt at a temperature which is above the what say melting temperature then it cools down to the what say melting temperature then it cools down to the solidus temperature then to the room temperature. In this process there will be shrinkage finally, we may what say pour the molten metal may occupy all the corners and get the exact shape of the mould cavity, but finally there may be shrinkage defects. Sometimes it becomes very difficult to overcome these shrinkage defects, but here what is happening during solidification we are applying pressure. First of all we are not heating the melt above the liquidus temperature. The melt is heated between the liquidus temperature and the solidus temperature. So, the what say temperature is not very high it is in a slurry form then we are injecting into the 2 days. So, there will be minimum shrinkage even if there is a shrinkage we are applying external pressure because of that the shrinkages will be totally eliminated. So, there would not be any shrinkage porosity even if what about the gases sometimes what say dissolved gases will be there even if there is some dissolved gas inside the melt then what happens because we are squeezing the melt these dissolved gases will be escaping out. So, the casting will be free from shrinkage porosity and also from the gas porosity. Next one we get the excellent mechanical properties to the cast components right. So, in the case of the casting mechanical properties may not be very good, but whereas in the case of the forging and other forming process mechanical properties are very good. Now in the case of the semi solid metal casting we are taking the advantage of metal casting as well as that of the forging. So, we get the very good mechanical properties. Next one close dimensional tolerances means we get very good dimensional accuracies. Next one thin walls can be very successfully produced and castings are heat treatable. So, these are the advantages of semi solid metal casting process these are the disadvantages of semi solid metal casting production facilities need a high level of technology right. So, the molten what say slurry has to be heated above the liquid temperature and below the solidest temperature. So, it requires a high level of technology and the staff who are working with this they should have the what say sound knowledge of what say these temperatures. Operators require similar knowledge and training. Now with this we are completing the semi solid manufacturing. Now let us see another variant of what say die casting. So, that is the vacuum die casting. Now in the vacuum die casting the process is similar to die casting right, but what is the difference? Here we can see this is the die. Die means a set of dies two dies will be there and between these two dies again there will be a cavity whose shape is similar to the component which we want. Now here we can see this is the furnace. This furnace is an integral part of the machine. Now this is the what say channel through which the molten metal enters and it fills into the cavity, but here during what say while the metal is what say carried to the set of the dies the way the molten metal is entering into the cavity makes the difference. In the case of the what say hot chamber pressure die casting machine we apply what say external pressure on the plunger. As the plunger comes down the molten metal enters into the cavity and here what is happening? The molten metal enters into the cavity because of the vacuum that we apply and here we are applying vacuum there will be vacuum pump you can see here. So, this is the vacuum what say line is coming here and it is applied to the what say die casting this dies. Now as the vacuum is causing suction what will happen the molten metal will be automatically entering into the mould cavity. We are now applying external pressure while the molten metal is entering into the cavity. Once the molten metal enters into the cavity then we apply the external pressure here we can see there is a plunger. So, this plunger will be moving. So, this is the suction of the molten metal from the metal bath due to the application of the vacuum. Then what will happen? Injection of molten metal into the die now here there is a piston is there this piston will be what say moving forward and it causes pressure and the molten metal will be injected into the set of dies. Now here vacuum always closed next what will happen? There will be solidification now component will be solidified the casting will be solidified. Now these are the advantages of vacuum die casting high quality of molten metal because we are applying vacuum. So, no atmospheric contamination no oxidation. So, that is how we get the high quality of molten metal. Next one erosion of piston and diffusion of iron may not takes place as in the case of the plunger type hot chamber die casting process. Now in the case of the plunger type hot chamber die casting process what is happening? We apply the what is a pressure on the what is a plunger that plunger goes inside the what is a that is cylindrical barrel. As it comes down the molten metal will be injected inside the two dies. Now in this process the what is a plunger is made up of certain hard materials. Now maybe like tungsten or molybdenum. So, these what is a hard elements like tungsten or molybdenum few atoms will be removed from the plunger and they will be diffusing into the molten metal. Now what is the what is a result? Because these are hard elements the cast component will have a what is a properties the mission ability will be very poor. So, that is the diffusion or erosion diffusion or erosion one takes place as in the case of the plunger type hot chamber die casting process. Next one in the hot chamber what is a pressure die casting process there is another type that is the air injection type. The air will be pressurizing the molten metal and the molten metal will be injected into the dies. Now in this process as the air is coming down as it is applying pressure on the molten metal the oxygen present in the air will be reacting with the molten metal and causes oxidation that would not happen in the case the case of the vacuum die casting. Oxidation of molten metal may not takes place as in the case of the air injection type hot chamber die casting process. Next one the casting is free from dissolved gases these are the disadvantages of vacuum die casting cost of production goes up because we are applying the vacuum. So, this itself makes the process costly. Next one operation requires skilled workers means in the right time vacuum has to be applied in the right time vacuum has to be stopped. So, this requires skill and the knowledge that is how the operation requires skilled workers means the cost of production goes up because of the trained workers and skilled workers. Next one so these are the some of the what is the examples of the vacuum die cast parts this is an automotive frame these red colored what is a parts. So, these are the what is a parts produced from the vacuum die casting. So, this is the automotive frame. Now let us say the factors influencing the quality of pressure die cast components. One is the injection velocity during the casting cycle. Next one injection pressure. Next one time of filling the mould cavity. Next one temperature of cast alloy. Next one temperature of the chamber and finally temperature of pressure die. Now we will see die casting defects what are the defects that are likely to arise in the die casting process. So, there are three categories of die casting defects. One category first category is the surface defects, second category internal defects, third category dimensional defects. Under the surface defects we have shouldering blisters and cracks. Under the internal defects we have inclusions gas porosity and shrinkage porosity. Under the dimensional defects there will be thermal expansion or contraction. So, first we will see the shouldering. Shouldering is the fusion of aluminium means the cast material with iron from the steel surface of the die cavity. The dies are made up of ferrous alloys. So, when we are casting what is a aluminium cast components in the die casting process this molten metal can react with the iron of the steel dies. Generally what will happen? An oxidized coating on the die cavity protects the cavity surface from the aluminium. There will be an oxidized coating will be there, but if the alloy impinges means it comes and strikes the alloy at a high pressure then what will happen? A portion of the die corp in the aluminium will break down the oxidized interface between the die surface and the casting. Now, if the molten metal comes and impinges on the what is a steel blocks what will happen? So, because of that the oxidized coating will be broken. That time the cast metal the aluminium may react with the iron in the steel blocks or the iron in the steel dies. So, when shouldering occurs in the die casting die the casting sticks to the cavity then what will happen? Consequently the molten aluminium alloy will be sticking to the what is a dies. So, this is the typical appearance of shouldering defect you see here. So, this is the background is the die and the molten aluminium is sticking to the die surface. Die is damaged and the casting is also damaged. Second one second category second defect is the blister. What is this blister? Blisters are bubble like bumps on the castings surface. Gas is trapped near the casting surface cause them. When the casting is what is a ejected and the casting surface over the blister is not strong enough to withstand the gas pressure the surface yields and develops the blister. Let us see its appearance yes this is the casting here we can see a kind of a defect like a bubble. So, this is the blister you can see here this is the blister. Next defect is the crack. It is a linear discontinuity of the surface of the die casting it is a linear discontinuity. The two major causes for cracks are one is the insufficient temperature of die. If the casting die is comparatively cold as the casting preaches there will be excessive internal stresses in the casting. So, this leads to what is a crack. There is another reason excessive temperature of the die. If the die is too hot usually in a local area at a particular what is a point crack forms due to shrinkage. So, these are the two reasons responsible for the formation of the linear discontinuities or the cracks. So, this is the typical appearance of a crack here we can see these are the cracks. Next one let us see the second category that is the internal defects under that we have the inclusions. The vast majority of these inclusions is non-metallic aluminum oxide. Other inclusions are silicon carbide, flux, sludge and so on. And here we can see aluminum oxide inclusion. Next one gas porosity under the internal defects. Gas porosity is due to trapped gases. Now, what are the sources of these gases? Trapped air in the furnace air in the cold chamber or gases from excessive lubricants we use lubricants. So, that time also from the lubricants gases will be erased. Now, other causes for gas porosity improper winting there should there will be wind holes to the dies. If these what say wind holes are not enough to allow hot gases that time also this gas porosity defect will arise. Now, this is the typical appearance of gas porosity here we can see these are all the gas porosities. Now, let us go to the third one under the internal defects that is the shrinkage porosity. Shrinkage defects occur at the last place in the casting during final stage of the solidification. Shrink porosity is characterized by a rough and jagged appearance in contrast to the smooth appearance of gas porosity. So, there will be two porosities one is the shrinkage porosity and another one is the gas porosity. So, shrinkage porosity is characterized by a rough appearance insufficient pressure and uneven thicknesses of sections are common causes of shrinkage porosity. Now, let us go to the third category that is the dimensional defects thermal expansion or the contraction. A dimensional problem can occur when one half of the die is much hotter than the other half. There will be two dies that we know very well these two dies must be at the same temperature. If one half of the die or one die is hotter than the other half this problem can occur. Flash buildup at the parting line may develop which prevents the die from closing properly. It ultimately leads to dimensional problems expansion or contraction. Now, let us see the dies and die materials. Now, what are the materials used to what is a manufacture the dies? The dies should have enough what is a hardness they should have enough hot strength they should have enough fatigue strength. So, die should have very what is a good properties and it should have what is a ideal properties. Now, what are the materials used for making these dies? So, what is the important materials are? So, these are known as the steels right H11 steel, H12 steel, H13 steel, H19 steel, H20 steel and H21 steel. So, this is the what is a these are the what is a elements that are present in these steels. Carbon is present in all these steels besides carbon chromium will be there, molybdenum will be there, tungsten will be there, vanadium, cobalt and nickel. In the case of the H11 steel carbon content is 0.35, chromium content is 5%, molybdenum 1.5, no tungsten, vanadium 0.5 and balance is iron and this steel is used for making zinc casting dies. Next one H12 steel, carbon content is 0.35, chromium 5%, molybdenum 1.5%, tungsten 1.5%, vanadium 0.4% and balance is iron. So, this is used for making aluminum casting dies means when we have to make aluminum castings. So, for that the dies are made up of this H12 Next one H13 steel, carbon content 0.35, chromium 5%, molybdenum 1.5%, vanadium 1% and this steel is also used for making aluminum castings. Next one H19 steel, carbon content 0.4%, chromium 4.25%, tungsten 4.25%, vanadium 2% and cobalt 4.25%. And this is used for making this what say steel is used for making brass and bronze castings. Next one H20 steel, carbon content 0.35, chromium 2%, tungsten 9% and this steel is also used for making the dies in the case of the bronze and brass castings. And finally H21 steel, carbon content 0.35, chromium 3.5, tungsten 9%. So, this is also used for making the dies where brass and bronze castings are to be made. So, in all these cases iron is the base element. Now die casting types, dies types, what are the types of the dies? So, there are four types of dies are there. One is the single cavity die produces one casting at a time. Second one is the multiple cavity die produces more than one casting at a time. Next one family die produces number of different parts. Here also different parts are there, but same casting more than one casting, same casting, but here different castings. So, that is the family die. Next one unit die, a unit die allows use of replaceable couties in the standardized main die frame for low at lower die costs. And here we can see this is the single cavity die means, so this is the shape of the what is a cast component. Only one component can be produced at a time. So, that is the single cavity die. Now, this is the multiple cavity die and here we can see this is one casting, this is one casting, this is one casting, this is one casting and this is one and this is one. At a time in this type we can see there are six couties are there, but all the couties are similar. So, at a time with one injection we can produce six similar castings. So, this type of die is known as the multiple cavity die and next one is the combination die. In the combination die we can see different parts can be produced. This is one part and this is one part and this is one part. Now with one injection these different parts can be cast at a time. So, this is the combination die and this is the unit die. So, this unit die what is a includes a replaceable die at a lower cost that is the unit die. Now, what is let us see quickly how to make the or how to manufacture the die. When manufacturing a die casting die the following are of vital importance, machinability, electrical discharge machining, heat treatment, dimensional stability, surface treatment and weldability. Now, costs involved in die making you can see here this is like a like an iceberg you see one a little cost is appearing outwards apparently say this is the steel cost may be this much and this is the die making cost. So, only this much appears to be what say manufacturing or the what say die cost, but there are several hidden costs are there. Production and maintenance cost say preheating is there we have to do the welding and scrap will be there that also costs us heat treatment repair will be there, last production adjustment will be there, delivery delays and etcetera all these elements contribute to the total cost of the die. So, these are the costs involved in the die making. Now, die maintenance before injecting the metal make sure that the die has been preheated to preheated to 175 degrees centigrade. So, this is the first step in the die maintenance. When the die casting machine is running run consistent cycle times with each cycle element consistent heat expansion contraction stress should be uniform. Next one minimize build up on the cavity surfaces this could be shoulder carbon or waxes usually a result of inappropriate die release application. So, we have to minimize the build up on the die cavity surfaces. Next one is the die spray. Die spray can be applied through different methods. A manually held spray next one individual spray nozzles mounted in fixed positions on the machine or the die. Next one a series of spray nozzles mounted on a moving arm that reciprocates in and out between the open die faces called reciprocator. A series of spray nozzles mounted on a moving arm you can see here spray is it is what is a spraying is going on and these spray nozzles are mounted on a moving arm. And here we can see this is one die and spraying is going on and finally these are the structural components of a die casting machine. What are the structural components of a die casting machine? We have learnt different types of what is a die casting machines and different types of the what is a variance in the die casting process and what are the finally what are the structural components? One is the stationary plating, second one is the moving plating, third one is the rear plating, fourth one is the tie bars, next one is the toggle mechanism, next one electrical components and finally hydraulic system components. So, with this we are completing the die casting process. So, friends in this lecture we have seen two advanced variants of the die casting process. One is the semi solid manufacturing that is the what is a the metal is heated above the liquidage temperature and below the solidage temperature then it is injected into the dies. Again we have seen different types of the semi solid manufacturing and other variant is the vacuum die casting. So, with this we are completing the die casting process and in the next lecture we will be learning about the investment casting process. Thank you very much.