 Hello friends, I am Satish Araparyan, working as an assistant professor in Department of Mechanical, Vulture Institute of Technology, Sholapur. Today, we are going to understand the term green sand molding. At the end of this session, we will able to understand what the term green sand molding stands for and its extent up to what are the advantages and limitations. Now, coming to the content of this session, first we will understand what is green sand molding, what are the steps involved in green sand molding, what is or what are the different advantages of green sand molding compared to other and what are its limitations in green sand molding. First, we will understand the term called green sand molding. Among the sand casting processes, molding is most often done with the green sand. Green molding sand may be defined as the plastic mix of silica, sand grains, bonding agent, clay, water and other material. See, whenever we want to cast something, the molding process involves the mixture of molding, silica sand, then second what is the, how the sands will be mixed and what will the bonding agent in that case, clay will be used, water to extent will be used and other different materials upon its requirement are used. First, why it is called green sand molding? We have to understand why it is only called green sand molding? The green sand molding, the sand is called green because of its moisture content present and hence it is clearly distinguished from the dry sand. In dry sand molding, the sand is distinguished because it is totally dry in content which is only dried. Now, coming to next slide, what are the different steps involved in green sand molding? First, in any molding processes, first the first and foremost step is called pattern making. Without pattern, we cannot mold anything. So, pattern making is the first and foremost step and in generally green sand molding among there are n number of types of pattern available. So, among that the first and foremost pattern which is generally used is match-plated cope and drag type of pattern. We will see this in next coming slide, how what is known as match and cope drag type of pattern. The second step involved in green sand molding is mold making. Now, when pattern is ready, cope half is ready, drag half is ready. Because the sand is put into that pattern, ramming of sand is done around the pattern. This ramming helps to develop the strength because when whenever we ram it, the grains start coming together. As a result of this packing, sand develops a good strength and becomes rigid within the flask. Then if any core type of is required, cores are required, then core setting is another step which is involved after mold making. After molding of two halves means first core, cope half is done, then drag half is done. After involvement of cope half, after making of cope and drag as a different parts, after molding of two halves is complete, cores are set into mold cavity if required. Cores may be or may not be required upon their requirement compared to the part. There are n number of sets where core is definitely required. So immediately after mold making, core setting has to be done. If cores are not placed proper, n number of defects will be involved and or else if core setting is done afterwards, we will think that how we will try to make it in some other way. So that also can be a big question and that also can lead to different type of defects over a period of time. Now when pattern is made, molding is made, ramming of sand around the pattern is done to its strength is required, this ramming with the help of water and other agents when total is done, core setting is done, then finally the two parts has to be closed together. Means it is called closing and clamping which is called also weighing. After core setting, cope and drag are closed, cope is generally weighed down or clamped to drag to prevent it from floating when metal is pulled. I am repeating after core setting, cope and drag are closed, cope is generally weighed down or clamped to drag to prevent the floating of floating when metal is pulled. Now please see this figure which is involved, a green sand process is done. Where the pattern is placed, what are the different elements, the cope half, the drag half, the sand half, see the cope half is upper part what is shown in the bottom figure, the drag half is down figure where sand is done, clamping you can see it is noted between cope half and drag half, I can show you here, see these are the clamping has to be done here and see this is the parting line here we can see the parting line is involved, parting line is the line which at that place, cope half and drag half has been cut off we can say, two parts are to be removed or clamped together, at this part we can see cope half, see whenever what happens first cope half in green sand molding this is the suppose we can say this is the part pattern what has been put, this sand is involved, this sand is rammed here put this is rammed put together means totally the ramming is done, this sand is green in color what we are now speaking here is green color we have that it develops the strength because they come closer the green start coming closer then after this, this is the part cope part which has been placed above this drag part now see this is this was the one part, this is the another part right after this when this also has been complete after this then we will we are left with this shape around that in the metal pores when pattern is removed what is the purpose this pattern when it is removed this pattern will be removed and the metal when from flow it will come it will pass on year and year this put together it will make this part available after this part is available then what happens it it will be allowed to solidify this pattern will be removed first then the metal will be poured here in green sand molding what is our purpose this is the sand is green in color not the sand is not green in color the sand is called green because of its moisture content so this will be removed and then this cavity will be left for pouring the metal will be poured it will be moving from year to year direction will be given and this will study over a period of time that this will be help this it will be done with the help of gating systems involved so this part will be produced as it is means we can say the pattern what is there is the exact replica of the part what is desired what is required see the clamping is also done also we need to understand this clamping has to be in either proper places or design in the proper places because if it they are not designed properly when the molten metal starts coming in there is a upper buoyance force which because of that force this part can lead to some mismatch over this parting line many times there are different defects or involved like some parting line defects or some other things so this has to be done very properly proper care has to be taken in that case so we'll see after see you can see first this pattern is placed then sand is rammed over it then these parts are placed and this is put together again the ramming is done and then finally this pattern will be removed and from this the molten metal flows into this and then this part exactly what will be required in that case so these are the different steps if at all any core see we can see some core has been placed core are been placed also we can not only cores there are certain chills also is required if certain directional certification is required certain chills are been required now after coming talk we'll understand what are the advantages of green sand molding the first four mode advantages of green sand molding is most metal almost all metals can be cast by this process second there is no limitation with respect to size of the casting and type of metal alloy used means in grief with the help of green sand molding any size the size is not a constraint and any metal alloy can be used third is foremost important the most it is economical because pattern cost and material costs are relatively lower it is least cost method of molding what we'll say second the flexibility as mechanization reduce of sand is there after the first part is done the second batch can be used with that the same sand so flexibility cost also will be reduced in that case and ease to adaptability now think for two minutes or some seconds what are different parts around you which are made from this process jot down some parts which are around you which can be made with the help which are the casting parts around you which can be made with the help of green sand molding now coming to next part what are limitations of green sand molding some casting designs require use of other casting processes the example of this is air cooled engine cylinder box so only with the help of green sand molding this cannot be done the second is the certain metals and some casting develops defects if poured in green sand molding especially is called magnesium alloy intricate castings are difficult to cast dimensional accuracy and surface finish may not be educated so with the help of another process which are some advance molding processes this can be avoided larger casting requires greater molding and hence resistance to erosion that then available increase green sand so even though we can make a big castings but we have the question of erosion of the sands sand mold available now what are the references used in this is NPTEL second a book PLGEN principles of foundry technology and some slideshare notes available thank you