Foundry Tools and Casting Processes Overview

Because this is the second lecture on foundry shop. In the last lecture we have already covered the topics. Those are you can see in the black color. Today we are going to cover the remaining headings that you can see. Foundry tools, types of furnaces and casting defects. So there are different kinds of foundry tools that we are going to see one by one. Here you can see some rough pictures. These are certain. foundry tools and foundry tools are used to prepare the mold and after that in the furnace we actually prepared the molten metal and that is finally poured into the mold cavity and finally the cast product is produced so this is what is done in the foundry shop so to discuss about the foundry tool let us see one by one all these different kinds of tools so we'll start with This one which is hand riddle, it is basically used to cleaning the sand. Okay, to remove nails, shorts or metal pieces, splinters of wood may be there in the sand. So to clean the sand basically hand riddle is used. And here you can see how the Sand is cleaned in the riddles. Here you can see the mesh is there with the help of the wear mesh that is created in the riddle. And the distance between nearby points in the mesh, if that distance is say 4.75 mm, then the sieve size is 4.75 mm. Okay, so you can understand there are different grades of mesh depending upon the size which are required and sometimes what is done, you can see the arrangement here, the larger mesh size and gradually the mesh size is decreasing. And finally, you can see the 4.75 millimeter is a fine mesh sieve which is used and the whole thing is basically kept on a vibrator and maybe uh some sand is poured at the top and gradually uh it is passed through this and finally the fine sand found at this particular bottom okay so there are different techniques by which this can be done other than hand riddle there are machine riddles also for the big projects this can be used okay now coming to the next one which is the shovel Now shovel you can see that the two parts one part the front part is the metallic one another one is the wooden one and the shovels are used to transfer sand from one place to another that you can see here and this is also used to mix the sand with the clay and that is also that means to prepare the green sand the shovel is also used okay. now coming to the next one which is the rammer so there can be different kinds of rammer here for the small molds you can see this kind of hand rammer the pin type hand rammer which are used or it can be very large size or the machine rammer are also there in the industry so it is used for striking the molding sand compacting the sand around the pattern so this is With the help of a rammer you can see that the sand is basically compacting. The green sand is compacting and the mold is prepared. Next you can see this is the sprue pin and the sprue pin actually used to create the sprue and sprue is basically the passage through which the molten metal goes into the runner and finally through the gates it goes to the mold cavity okay to create that a sprue the sprue pins are required so here you can see that these sprue pins are there and after that what is done these sprue pins are actually taken out and it will leave a passage And that particular passage or the cavity of the shape of this sprue pin is called the sprue. So to create the sprue, we use the sprue pin or to create the riser, we use the riser pin. Okay, so in this particular video that there are two pins which are used. One is the sprue pin, another one is the riser pin. Okay, riser pin is basically used. when the complete mold cavity is filled with the molten metal, then the excess metal will gradually rise in that cavity, that riser cavity. Okay. And the sprue pin, you can understand it is used to pour the molten metal to create through the sprue. Okay. So, and you see that how these are actually used. Here you can see this is another tool which is basically used to remove the excess sand from the cope part. You can see that excess sand can be removed smoothly from the surface and this particular tool is called strike off bar. Strike off bar is actually strike off the excess amount of sand. from the cope. So now you can see that another tool which is basically the lifter is also used here as a strike off bar. So after venting with the venting wire you can see These are removed and this left two holes one is the riser hole another one is the sprue. Okay this is the passage. This is the passage where the molten metal is poured here. And if you observe carefully, this part is wide enough. This is what is called the pouring basin. And after that, this taper hole which is actually created with the help of this sprue pin. And this is what is called sprue. and after that it goes to the this position which is you can call sprue well or whatever and after that it goes through this common passage which is called the runner this common passage through which the molten metal flows is called runner and finally from the runner there may be multiple gates through which it goes to the mold cavity okay so these are called the gates these are called the gates and this common passage through which the molten metal flows is called runner okay and here you see over the mold cavity this is what is the riser this is riser and for to create this riser again you need another pin so another pin is the riser pin so one is the sprue pin another one is the riser pin okay so riser pin creates this riser so when the excess molten metal the complete more mold cavity is filled with the liquid metal that will gradually rise and from outside from here we will be able to observe okay now riser is filled up that means the mold cavity is filled up with the molten metal okay so riser that is what is the purpose of providing riser is that why the pin is taper okay why the pin is taper so the first thing which is coming to your mind may be direct if you give the molten metal if the pin is not tapered like this in that case what may happen that the turbulence will be more you And there will be chances of the air bubble formation. Okay, some of the air bubbles may form within the liquid metal and that may create some kind of casting defect. Okay. So if you make it taper then definitely the flow of the molten metal to the runner will be gradual. This is the first thing. Second thing, the important point that why it is made taper is to avoid the aspiration effect. What is aspiration effect? As you can see if you make it like this. There is a chance that at this region the pressure will be very very small. So if the pressure is very very small then at that time there is a chance that the gases that will form contact with the hot molten metal with sand it is possible that some of the gases may come from the mold side into the molten metal okay so this is what is called the aspiration and chances of aspiration will be more if you make it straight if you make it gradual then in that case the pressure is almost uniform okay pressure variation will not be there along the length otherwise if you make it straight you will find that the low pressure region will be created below atmospheric pressure will be created and outside the gases which are entrapped maybe within the molding sand those If the pressure is very low here and their pressure is atmospheric pressure then what will happen? Those gases will come into this molten metal and mix with the molten metal. To avoid this aspect, we will use a liquid. aspiration effect basically we make it taper. So these are the two important points that you remember. Another thing, the third point that I should mention about the gating system is that you will find that when you are cutting the gates at that time you will find that gate is basically the passage through which the molten metal flows finally into the body. cavity mold cavity so in that case you'll find that the inclination is like this that means if this is the mold cavity so the inclination is against the gravity not in the direction of gravity against the gravity a small amount of adverse slope is used so that molten metal will not flow very easily into the mold cavity directly because initially it is poured from a very long maybe through this long sprue so there is a chance its velocity will be very high so we want a gradual pouring okay that is why this adverse angle is provided so that gradually it goes to the mold cavity okay so these are the certain things you try to remember regarding the getting system and these are basically the different terms that you can see with respect to the getting system getting system means the passage through which finally molten metal goes into the mold cavity so the pouring machine then sprue then maybe the sprue well you can see and then the runner then gates so these are the different uh portions of the or the different parts of the grading system that you try to remember next see this is what is called travels travels are very common we have seen travels in the machinery work and that is used for finished flat surfaces and corners in the mold as you can see here the surfaces is flat with respect to the with the help of the travels okay next is the lifter as you can see that lifter is a finishing tool repair and repair the mold and finishing the molding sand okay so for the finishing work for repairing the mold cavity these lifters are used it is also used to remove the loose sands maybe fall into the mold cavity when you are basically taking out the pattern it is possible so those kind of works can be done with the help of lifter here you can see that one gate is actually cut near the mold cavity and with the help of this lifter that particular gate is actually repairing or final finishing is given with the help of this lifter here next strike off bar already you have seen that how strike of car works it is a flat bar it can be made of wood or Iron to strike off the excess sand from the top of the box after ramming, okay Next vent wire or the vent rod. This is a steel rod or wire with pointed edge at one end and handle or vent loop on the other end. As you can see this is what is the vent wire and after the use of the venting wire is to create the passage for the gases or the steam. so that they can come out from the molding sand to the outside air. Okay, so after ramming and striking off the excess sand, it is used to make small holes called the vent. in the sand mold to allow the exit of gases and steam during casting so this is a very very important if we don't do not vent properly do not create vent properly within the mold there is a chance that the gases will not be able to escape out and that will ultimately create lot of defects within the casting. And we'll see that what kind of defects actually happens because of this at the end of this lecture. Next is the Sleeks. You can see there are different shapes and sizes of Sleeks are there. Maybe the spoon size or some kind of a cutter kind of a thing. Maybe they are at the ends. Okay. So they are also recognized as a small double ended mold finishing tool and which are generally used for repairing, finishing the mold surfaces and their ages after withdrawal of the. Pattern, okay. So here you can see with the help of these slicks In the top picture you can see with the help of this leak. Basically the pouring basin is created okay, so pouring basin if you remember a respectively large diameter at the entry of the Sprew that is created with the help of this leak or you can see that as a gate cutter slick slick is used you can see that this is the mold cavity you can see and the gate is cut with the help of this slick tool because the edges of this leak tools are very sharp maybe those also can be used to create the gate along with the lifter and all these things you have seen earlier now swap uh swap that it is a small hemp fiber brush at the end some fiber brush is there used for moisturizing the edges of this animal which are in contact with the pattern surfaces before withdrawing the pattern okay so just before you train the pattern it is required to moist the edges uh of the mold with the pattern so that the removal will be easy and it is not going to break the mold edges okay so here you can see in this video so how the swab is used so here you can see the moisture which is coming out from the swap tool and this actually helps removing the pattern from the mold easily after watch So next is the gate cutter. So gate cutter is a small shaped piece of sheet metal commonly used to cut the runner or the feeding gate for connecting screw holes with the mold cavity. But slicks can also be used as a gate cutter. As you have seen here, slicks can be used as separate sheet metal gate cutters are also used. Billows, this is actually used to give the high velocity air jet to remove the sand from the surfaces where maybe directly using some tool or hand is not possible so there pillows can be used so as you can see the construction from the side basically air is coming then with the help of this hand is you are giving the force so you have to give force like this continuously then what will happen through this nozzle air actually flow okay so this is how the pillows are used you can see here that it is hand operated leather made device equipped with compressed air jet to blow or pump air when operated so it is used to blow away the loose or unwanted sand from the surface of the mold cavity next you see the draw spike and it is a tapered steel rod having a loop or a ring at its end ring means basically the thread at the ends and this sharp point at the other end and it may have a screw thread on the end to engage the metal pattern and withdraw from the mold. So as you can see in this picture, the draw spike can have either the screw threaded at the end. So in that case, what we do similarly in the pattern corresponding internal thread is also there. So what is done with the help of this draw spike? you can attach with the pattern and then you can take it out gradually. Or maybe there is no screw thread is there only the sharp edge like spike is there and with the help of some striking tool we first insert it and then gradually we taken out the pattern from the mold cavity. See in this video. So here you see that the draw spike. Here you see the draw spike. is used to first insert it into the pattern and then by small striking it is taken out from the mould. so it is actually helping to draw the pattern from the mold that is why the name is draw and the spike comes from the fact that the other end is like spike a sharp edge okay now coming to the molding box as you know that there are cope part which is at the top and the drag part which is at the bottom and this is how the molding box looks like this is also called the molding flask depending upon the complicated pattern sometimes maybe the more than two boxes like three boxes can be used in that case is the intermediate molding flask is called the cheek as you can see here bottom one is always the drag and the top one is the cope the middle one is the cheek okay so Next is crucible. Crucible is basically this kind of a thing. You can see this kind of a pot which is made of generally ceramic material. And within that we keep the scrap of the metal that is to be melted which is called the charge. Okay, charge means the scrap of the metals which we want to melt and finally poured into the cavity. So scrappy. scrap or the charge is kept inside the crucible and then in the furnace this crucible is kept and ultimately it will melt inside the crucible and then with the help of crucible tone as you can can see there are different kinds of tongs internal external this kind of talk there the help of that we take out this crucible maybe from the furnace and then fix on the handle or the crucible holder so possible or the ladle holder this a crucible the same thing is also you can call it as a ladle ladle and crucible are the similar kind of a thing where the molten metal actually stored okay So then you can see here these are the handles or the holders where the crucible is. kept and then the molten metal is poured into the mold cavity. So here you can see, so here within the crucible you can see the charge is kept, charge means the scrap metals which we want to melt. See with the help of crucible tong it is put within the furnace. With the help of tong The crucible is taken out from the furnace. Then it is placed within the crucible holder or the crucible handle. And then it is locked. Okay. And finally, after removing the slags, the molten metal is poured into the mold cavity. Now coming to the furnaces and there are different kinds of furnaces, foundry furnaces possible. Broadly they can be categorized into four types. Cupola Furnace, crucible furnace electric arc furnace and induction furnace now first we'll see one by one the cupola furnace and in the picture you can see this one is the cupola furnace this one is the cupola furnace and in the cupola furnace what happens you see that initially here it is the charging door through which basically the coke which is basically the carbon coke and the metal metal is basically the iron ore the iron ore and some flux like limestone basically which is Given so this mixture is basically what is the charge material here in case of a cupola? So within cupola what happens basically? Air is supplied from the bottom air is supplied from the bottom Okay, so air is blasted from the bottom and air goes in the other direction and the charge moves in the downward direction. So you have carbon, you have oxygen, you have iron oxide that means which is the iron ore okay so they react and because of the chemical reaction a huge temperature is created and because of that huge temperature and the iron oxide actually converted into iron and at that high temperature that iron melts okay and that melted iron actually comes here and from here it is taken out okay so in this way the molten metal is collected here and this is what is the how cupola works and this is mainly used to create the cast iron melted cast iron we use cupola next you see the crucible furnace in the crucible furnace this one is the crucible furnace this one is the crucible furnace the crucible furnace here you can see this is what is the crucible And within the crucible definitely the charge is there. Charge means you know the scrap metal that we want to melt. Scrap is there. And outside here basically as a fuel. may be coal or it may be some gaseous fuel whatever that may be there and with the help of air and we just with the help of a burner we create combustion outside the crucible so here huge heat is generated and that energy the heat energy actually transferred through the crucible material so crucible material should be made of highly thermally conductive material they are generally made of graphite or silicon carbide this kind of a material okay so they are very hard material at the same the basic thing the for the procedure material requirement is the very high temperature melting point okay so they are melting point of the crucible material should be very very high and they should be thermally conductive highly thermally conductive so that is why the outside high temperature or the outside source of heat can easily transferred through the crucible into the charge material okay so this is the way finally the charge material melted down and that can be taken out So this is what is the crucible furnace. Now coming to the electric arc furnace. In the electric arc furnace as you can see this is the picture of the electric arc furnace where you can see the charge material is kept here. Here is your charge material which is kept here and the electrodes. These are the electrodes. and high voltage so you need the electrical energy source so high voltage is created between these electrodes and the charge material okay so if you create high voltage between this electrode material and the charge then what happens basically arc is created and that arc ultimately creates the melt the so high temperature is generated and finally the metal here is melted. Okay so in this way we get the molten metal. So this is basically how this kind of electric arc furnace works. Now finally is the induction furnace. In the induction furnace You see that these are the constructions of the induction furnace, both of these constructions. So in induction furnace, actually outside there is copper coil there through which the AC current is flowing. And since the AC current is outside this furnace, here you can see these are refractory lining. These are refractory lining. Refractory lining means you know that they can resist very high temperature maybe some kind of refractory bricks or something and inside that you have the crucible. maybe this crucible just you have seen the crucible and in that crucible some charge material is there some charge material is there charge is there maybe aluminum or some whatever you want to make it now what happens actually so outside the current is flowing that is ac current and because of that magnetic field is continuously changing since it is ac so since the magnetic field is continuously changing so that is why inside the charge material which is thermally conducting that will create an electric current through that okay so that is what is because of the electromagnetic induction current will flow through the charge material okay and then because of the resistance of those charge material uh since the current is flowing this current is called the eddy current it generates because of electromagnetic induction and when this current is flowing and this charge material itself having some resistance electrical resistances and that is why what happens the because of the joule heating basically this molten material is there sorry this charge material is going to melt so heat source is basically the joule heating because of the induced current within the charge material and in this case there is no direct connection between this electric power lines around the around this furnace and the charge material and in this case you observe that it is not that the crucible should be required to be very highly thermal conductive. No, that is not required because heat is not actually coming from the outside to the inside. It is actually generated inside the crucible because of the electromagnetic induction. Okay, so these are the certain things that you should keep in mind that there is a difference between the crucible that is used within the crucible furnace and in the induction furnace. So in our lab, that the furnace that is there which is the induction type of furnace okay next we'll see the defects in casting and there are different kinds of defects that is produced in casting as you can see some of the names here so let us try to understand through a 3d visualization of each of the defects and try to know that what might be the reason of that through this youtube video This is due to lack of fluidity of molten metal. The molten metal solidifies before it fills the cavity. This leads to incomplete casting. Cold shut. Let us see an example for cold shut. Workpiece. Cold shut. Cold shut is a big depression that occurs in the surface of flat casting. It results due to the sand expansion caused by the heat of the metal. Hot tear. Let us see an example of hot tear. Job. Hot tear. Hot tear is a crack in the casting caused by high residual stresses. Flash. Let us see an example for flash. Cavity. Die Gap between two dies A thin web of metal on a casting which occurs at parting line is called flash. This flash is occurred due to gap between two dies. between two dice shift or mismatch let us see an example for mismatch job mismatch mismatch is a defect caused by a sidewise displacement of the whole group related to the drag which result in double the cost product at the parting line shrinkage let us see an example for shrinkage job shrinkage shrinkage is a depression or an internal void in a casting that results from the volume contraction During solidification of molten metal, flow depends. Let us see an example for flow depend. Casting, flow, flow is relatively large cavity produced by gases which displace molten metal from the cavity. Drop depend. Let us see an example for drop effect. Drop. Drop in a mold is an irregular shape projection on the cork surface of a casting. Scab effect. Let us see an example for scab. Drop. Scap Penetration Let us see an example for penetration Job Penetration Penetration occurs when the molten metal flows between the sand particles in the mould Warpage Let us see an example for Warpage Warpage is an indesirable deformation in a casting that occurs during or after solidification. Blowholes differ. Let us see an example for blowholes. Jaw Blow holes. Small holes below the surface of casting is caused by entrapped bubbles of gases. Porosity. Let us see an example for porosity. Chalk. Porosity. porosity is a small force on the surface of casting this is due to gas dissolved in the alloy pin fold let us see an example of pink pole part pin force pin force or small gas force either at the surface or just below the part surface so you have seen the different kinds of casting defects so thank you

Foundry tools, types of furnaces and casting defects. So there are different kinds of foundry tools that we are going to see one by one. Here you can see some rough pictures.

These are certain. foundry tools and foundry tools are used to prepare the mold and after that in the furnace we actually prepared the molten metal and that is finally poured into the mold cavity and finally the cast product is produced so this is what is done in the foundry shop so to discuss about the foundry tool let us see one by one all these different kinds of tools so we'll start with This one which is hand riddle, it is basically used to cleaning the sand. Okay, to remove nails, shorts or metal pieces, splinters of wood may be there in the sand.

So to clean the sand basically hand riddle is used. And here you can see how the Sand is cleaned in the riddles. Here you can see the mesh is there with the help of the wear mesh that is created in the riddle. And the distance between nearby points in the mesh, if that distance is say 4.75 mm, then the sieve size is 4.75 mm.

Okay, so you can understand there are different grades of mesh depending upon the size which are required and sometimes what is done, you can see the arrangement here, the larger mesh size and gradually the mesh size is decreasing. And finally, you can see the 4.75 millimeter is a fine mesh sieve which is used and the whole thing is basically kept on a vibrator and maybe uh some sand is poured at the top and gradually uh it is passed through this and finally the fine sand found at this particular bottom okay so there are different techniques by which this can be done other than hand riddle there are machine riddles also for the big projects this can be used okay now coming to the next one which is the shovel Now shovel you can see that the two parts one part the front part is the metallic one another one is the wooden one and the shovels are used to transfer sand from one place to another that you can see here and this is also used to mix the sand with the clay and that is also that means to prepare the green sand the shovel is also used okay. now coming to the next one which is the rammer so there can be different kinds of rammer here for the small molds you can see this kind of hand rammer the pin type hand rammer which are used or it can be very large size or the machine rammer are also there in the industry so it is used for striking the molding sand compacting the sand around the pattern so this is With the help of a rammer you can see that the sand is basically compacting. The green sand is compacting and the mold is prepared. Next you can see this is the sprue pin and the sprue pin actually used to create the sprue and sprue is basically the passage through which the molten metal goes into the runner and finally through the gates it goes to the mold cavity okay to create that a sprue the sprue pins are required so here you can see that these sprue pins are there and after that what is done these sprue pins are actually taken out and it will leave a passage And that particular passage or the cavity of the shape of this sprue pin is called the sprue.

So to create the sprue, we use the sprue pin or to create the riser, we use the riser pin. Okay, so in this particular video that there are two pins which are used. One is the sprue pin, another one is the riser pin.

Okay, riser pin is basically used. when the complete mold cavity is filled with the molten metal, then the excess metal will gradually rise in that cavity, that riser cavity. Okay.

And the sprue pin, you can understand it is used to pour the molten metal to create through the sprue. Okay. So, and you see that how these are actually used. Here you can see this is another tool which is basically used to remove the excess sand from the cope part. You can see that excess sand can be removed smoothly from the surface and this particular tool is called strike off bar.

Strike off bar is actually strike off the excess amount of sand. from the cope. So now you can see that another tool which is basically the lifter is also used here as a strike off bar. So after venting with the venting wire you can see These are removed and this left two holes one is the riser hole another one is the sprue. Okay this is the passage.

This is the passage where the molten metal is poured here. And if you observe carefully, this part is wide enough. This is what is called the pouring basin. And after that, this taper hole which is actually created with the help of this sprue pin. And this is what is called sprue.

and after that it goes to the this position which is you can call sprue well or whatever and after that it goes through this common passage which is called the runner this common passage through which the molten metal flows is called runner and finally from the runner there may be multiple gates through which it goes to the mold cavity okay so these are called the gates these are called the gates and this common passage through which the molten metal flows is called runner okay and here you see over the mold cavity this is what is the riser this is riser and for to create this riser again you need another pin so another pin is the riser pin so one is the sprue pin another one is the riser pin okay so riser pin creates this riser so when the excess molten metal the complete more mold cavity is filled with the liquid metal that will gradually rise and from outside from here we will be able to observe okay now riser is filled up that means the mold cavity is filled up with the molten metal okay so riser that is what is the purpose of providing riser is that why the pin is taper okay why the pin is taper so the first thing which is coming to your mind may be direct if you give the molten metal if the pin is not tapered like this in that case what may happen that the turbulence will be more you And there will be chances of the air bubble formation. Okay, some of the air bubbles may form within the liquid metal and that may create some kind of casting defect. Okay. So if you make it taper then definitely the flow of the molten metal to the runner will be gradual. This is the first thing.

Second thing, the important point that why it is made taper is to avoid the aspiration effect. What is aspiration effect? As you can see if you make it like this.

There is a chance that at this region the pressure will be very very small. So if the pressure is very very small then at that time there is a chance that the gases that will form contact with the hot molten metal with sand it is possible that some of the gases may come from the mold side into the molten metal okay so this is what is called the aspiration and chances of aspiration will be more if you make it straight if you make it gradual then in that case the pressure is almost uniform okay pressure variation will not be there along the length otherwise if you make it straight you will find that the low pressure region will be created below atmospheric pressure will be created and outside the gases which are entrapped maybe within the molding sand those If the pressure is very low here and their pressure is atmospheric pressure then what will happen? Those gases will come into this molten metal and mix with the molten metal.

To avoid this aspect, we will use a liquid. aspiration effect basically we make it taper. So these are the two important points that you remember. Another thing, the third point that I should mention about the gating system is that you will find that when you are cutting the gates at that time you will find that gate is basically the passage through which the molten metal flows finally into the body.

cavity mold cavity so in that case you'll find that the inclination is like this that means if this is the mold cavity so the inclination is against the gravity not in the direction of gravity against the gravity a small amount of adverse slope is used so that molten metal will not flow very easily into the mold cavity directly because initially it is poured from a very long maybe through this long sprue so there is a chance its velocity will be very high so we want a gradual pouring okay that is why this adverse angle is provided so that gradually it goes to the mold cavity okay so these are the certain things you try to remember regarding the getting system and these are basically the different terms that you can see with respect to the getting system getting system means the passage through which finally molten metal goes into the mold cavity so the pouring machine then sprue then maybe the sprue well you can see and then the runner then gates so these are the different uh portions of the or the different parts of the grading system that you try to remember next see this is what is called travels travels are very common we have seen travels in the machinery work and that is used for finished flat surfaces and corners in the mold as you can see here the surfaces is flat with respect to the with the help of the travels okay next is the lifter as you can see that lifter is a finishing tool repair and repair the mold and finishing the molding sand okay so for the finishing work for repairing the mold cavity these lifters are used it is also used to remove the loose sands maybe fall into the mold cavity when you are basically taking out the pattern it is possible so those kind of works can be done with the help of lifter here you can see that one gate is actually cut near the mold cavity and with the help of this lifter that particular gate is actually repairing or final finishing is given with the help of this lifter here next strike off bar already you have seen that how strike of car works it is a flat bar it can be made of wood or Iron to strike off the excess sand from the top of the box after ramming, okay Next vent wire or the vent rod. This is a steel rod or wire with pointed edge at one end and handle or vent loop on the other end. As you can see this is what is the vent wire and after the use of the venting wire is to create the passage for the gases or the steam. so that they can come out from the molding sand to the outside air. Okay, so after ramming and striking off the excess sand, it is used to make small holes called the vent.

in the sand mold to allow the exit of gases and steam during casting so this is a very very important if we don't do not vent properly do not create vent properly within the mold there is a chance that the gases will not be able to escape out and that will ultimately create lot of defects within the casting. And we'll see that what kind of defects actually happens because of this at the end of this lecture. Next is the Sleeks.

You can see there are different shapes and sizes of Sleeks are there. Maybe the spoon size or some kind of a cutter kind of a thing. Maybe they are at the ends. Okay. So they are also recognized as a small double ended mold finishing tool and which are generally used for repairing, finishing the mold surfaces and their ages after withdrawal of the.

Pattern, okay. So here you can see with the help of these slicks In the top picture you can see with the help of this leak. Basically the pouring basin is created okay, so pouring basin if you remember a respectively large diameter at the entry of the Sprew that is created with the help of this leak or you can see that as a gate cutter slick slick is used you can see that this is the mold cavity you can see and the gate is cut with the help of this slick tool because the edges of this leak tools are very sharp maybe those also can be used to create the gate along with the lifter and all these things you have seen earlier now swap uh swap that it is a small hemp fiber brush at the end some fiber brush is there used for moisturizing the edges of this animal which are in contact with the pattern surfaces before withdrawing the pattern okay so just before you train the pattern it is required to moist the edges uh of the mold with the pattern so that the removal will be easy and it is not going to break the mold edges okay so here you can see in this video so how the swab is used so here you can see the moisture which is coming out from the swap tool and this actually helps removing the pattern from the mold easily after watch So next is the gate cutter.

So gate cutter is a small shaped piece of sheet metal commonly used to cut the runner or the feeding gate for connecting screw holes with the mold cavity. But slicks can also be used as a gate cutter. As you have seen here, slicks can be used as separate sheet metal gate cutters are also used.

Billows, this is actually used to give the high velocity air jet to remove the sand from the surfaces where maybe directly using some tool or hand is not possible so there pillows can be used so as you can see the construction from the side basically air is coming then with the help of this hand is you are giving the force so you have to give force like this continuously then what will happen through this nozzle air actually flow okay so this is how the pillows are used you can see here that it is hand operated leather made device equipped with compressed air jet to blow or pump air when operated so it is used to blow away the loose or unwanted sand from the surface of the mold cavity next you see the draw spike and it is a tapered steel rod having a loop or a ring at its end ring means basically the thread at the ends and this sharp point at the other end and it may have a screw thread on the end to engage the metal pattern and withdraw from the mold. So as you can see in this picture, the draw spike can have either the screw threaded at the end. So in that case, what we do similarly in the pattern corresponding internal thread is also there. So what is done with the help of this draw spike? you can attach with the pattern and then you can take it out gradually.

Or maybe there is no screw thread is there only the sharp edge like spike is there and with the help of some striking tool we first insert it and then gradually we taken out the pattern from the mold cavity. See in this video. So here you see that the draw spike. Here you see the draw spike.

is used to first insert it into the pattern and then by small striking it is taken out from the mould. so it is actually helping to draw the pattern from the mold that is why the name is draw and the spike comes from the fact that the other end is like spike a sharp edge okay now coming to the molding box as you know that there are cope part which is at the top and the drag part which is at the bottom and this is how the molding box looks like this is also called the molding flask depending upon the complicated pattern sometimes maybe the more than two boxes like three boxes can be used in that case is the intermediate molding flask is called the cheek as you can see here bottom one is always the drag and the top one is the cope the middle one is the cheek okay so Next is crucible. Crucible is basically this kind of a thing.

You can see this kind of a pot which is made of generally ceramic material. And within that we keep the scrap of the metal that is to be melted which is called the charge. Okay, charge means the scrap of the metals which we want to melt and finally poured into the cavity.

So scrappy. scrap or the charge is kept inside the crucible and then in the furnace this crucible is kept and ultimately it will melt inside the crucible and then with the help of crucible tone as you can can see there are different kinds of tongs internal external this kind of talk there the help of that we take out this crucible maybe from the furnace and then fix on the handle or the crucible holder so possible or the ladle holder this a crucible the same thing is also you can call it as a ladle ladle and crucible are the similar kind of a thing where the molten metal actually stored okay So then you can see here these are the handles or the holders where the crucible is. kept and then the molten metal is poured into the mold cavity. So here you can see, so here within the crucible you can see the charge is kept, charge means the scrap metals which we want to melt.

See with the help of crucible tong it is put within the furnace. With the help of tong The crucible is taken out from the furnace. Then it is placed within the crucible holder or the crucible handle. And then it is locked.

Okay. And finally, after removing the slags, the molten metal is poured into the mold cavity. Now coming to the furnaces and there are different kinds of furnaces, foundry furnaces possible. Broadly they can be categorized into four types.

Cupola Furnace, crucible furnace electric arc furnace and induction furnace now first we'll see one by one the cupola furnace and in the picture you can see this one is the cupola furnace this one is the cupola furnace and in the cupola furnace what happens you see that initially here it is the charging door through which basically the coke which is basically the carbon coke and the metal metal is basically the iron ore the iron ore and some flux like limestone basically which is Given so this mixture is basically what is the charge material here in case of a cupola? So within cupola what happens basically? Air is supplied from the bottom air is supplied from the bottom Okay, so air is blasted from the bottom and air goes in the other direction and the charge moves in the downward direction. So you have carbon, you have oxygen, you have iron oxide that means which is the iron ore okay so they react and because of the chemical reaction a huge temperature is created and because of that huge temperature and the iron oxide actually converted into iron and at that high temperature that iron melts okay and that melted iron actually comes here and from here it is taken out okay so in this way the molten metal is collected here and this is what is the how cupola works and this is mainly used to create the cast iron melted cast iron we use cupola next you see the crucible furnace in the crucible furnace this one is the crucible furnace this one is the crucible furnace the crucible furnace here you can see this is what is the crucible And within the crucible definitely the charge is there. Charge means you know the scrap metal that we want to melt.

Scrap is there. And outside here basically as a fuel. may be coal or it may be some gaseous fuel whatever that may be there and with the help of air and we just with the help of a burner we create combustion outside the crucible so here huge heat is generated and that energy the heat energy actually transferred through the crucible material so crucible material should be made of highly thermally conductive material they are generally made of graphite or silicon carbide this kind of a material okay so they are very hard material at the same the basic thing the for the procedure material requirement is the very high temperature melting point okay so they are melting point of the crucible material should be very very high and they should be thermally conductive highly thermally conductive so that is why the outside high temperature or the outside source of heat can easily transferred through the crucible into the charge material okay so this is the way finally the charge material melted down and that can be taken out So this is what is the crucible furnace.

Now coming to the electric arc furnace. In the electric arc furnace as you can see this is the picture of the electric arc furnace where you can see the charge material is kept here. Here is your charge material which is kept here and the electrodes. These are the electrodes. and high voltage so you need the electrical energy source so high voltage is created between these electrodes and the charge material okay so if you create high voltage between this electrode material and the charge then what happens basically arc is created and that arc ultimately creates the melt the so high temperature is generated and finally the metal here is melted.

Okay so in this way we get the molten metal. So this is basically how this kind of electric arc furnace works. Now finally is the induction furnace.

In the induction furnace You see that these are the constructions of the induction furnace, both of these constructions. So in induction furnace, actually outside there is copper coil there through which the AC current is flowing. And since the AC current is outside this furnace, here you can see these are refractory lining.

These are refractory lining. Refractory lining means you know that they can resist very high temperature maybe some kind of refractory bricks or something and inside that you have the crucible. maybe this crucible just you have seen the crucible and in that crucible some charge material is there some charge material is there charge is there maybe aluminum or some whatever you want to make it now what happens actually so outside the current is flowing that is ac current and because of that magnetic field is continuously changing since it is ac so since the magnetic field is continuously changing so that is why inside the charge material which is thermally conducting that will create an electric current through that okay so that is what is because of the electromagnetic induction current will flow through the charge material okay and then because of the resistance of those charge material uh since the current is flowing this current is called the eddy current it generates because of electromagnetic induction and when this current is flowing and this charge material itself having some resistance electrical resistances and that is why what happens the because of the joule heating basically this molten material is there sorry this charge material is going to melt so heat source is basically the joule heating because of the induced current within the charge material and in this case there is no direct connection between this electric power lines around the around this furnace and the charge material and in this case you observe that it is not that the crucible should be required to be very highly thermal conductive. No, that is not required because heat is not actually coming from the outside to the inside. It is actually generated inside the crucible because of the electromagnetic induction.

Okay, so these are the certain things that you should keep in mind that there is a difference between the crucible that is used within the crucible furnace and in the induction furnace. So in our lab, that the furnace that is there which is the induction type of furnace okay next we'll see the defects in casting and there are different kinds of defects that is produced in casting as you can see some of the names here so let us try to understand through a 3d visualization of each of the defects and try to know that what might be the reason of that through this youtube video This is due to lack of fluidity of molten metal. The molten metal solidifies before it fills the cavity.

This leads to incomplete casting. Cold shut. Let us see an example for cold shut.

Workpiece. Cold shut. Cold shut is a big depression that occurs in the surface of flat casting. It results due to the sand expansion caused by the heat of the metal.

Hot tear. Let us see an example of hot tear. Job. Hot tear. Hot tear is a crack in the casting caused by high residual stresses.

Flash. Let us see an example for flash. Cavity.

Die Gap between two dies A thin web of metal on a casting which occurs at parting line is called flash. This flash is occurred due to gap between two dies. between two dice shift or mismatch let us see an example for mismatch job mismatch mismatch is a defect caused by a sidewise displacement of the whole group related to the drag which result in double the cost product at the parting line shrinkage let us see an example for shrinkage job shrinkage shrinkage is a depression or an internal void in a casting that results from the volume contraction During solidification of molten metal, flow depends.

Let us see an example for flow depend. Casting, flow, flow is relatively large cavity produced by gases which displace molten metal from the cavity. Drop depend.

Let us see an example for drop effect. Drop. Drop in a mold is an irregular shape projection on the cork surface of a casting. Scab effect.

Let us see an example for scab. Drop. Scap Penetration Let us see an example for penetration Job Penetration Penetration occurs when the molten metal flows between the sand particles in the mould Warpage Let us see an example for Warpage Warpage is an indesirable deformation in a casting that occurs during or after solidification.

Blowholes differ. Let us see an example for blowholes. Jaw Blow holes.

Small holes below the surface of casting is caused by entrapped bubbles of gases. Porosity. Let us see an example for porosity.

Chalk. Porosity. porosity is a small force on the surface of casting this is due to gas dissolved in the alloy pin fold let us see an example of pink pole part pin force pin force or small gas force either at the surface or just below the part surface so you have seen the different kinds of casting defects so thank you

Transcript for:Foundry Tools and Casting Processes Overview

Transcript for:
Foundry Tools and Casting Processes Overview