Carbon-dioxide gas molding of sand casting processes

● The process is widely used for rapid hardening of molds and cores made up of green sand.

● The mold making process like conventional molding procedure only the content model consists of pure silica sand free dry clay, sodium silicate as a binder and 3-5% moisture content generally less than 3%.

● A small amount of starch may be added to enhance the green compression strength and a very small quantity of coal dust, sea coal, dextrin, wooden floors, pitch, graphite and sugar as possible to improve collapsibility the molding sand.

● The prepared molding sand rammed around the pattern in the box mold and mold is prepared by any conventional technique.

● After packing, carbon dioxide gas at about 1.3 to 1.5 kg / cm2 pressure then forced all round the mold surface to about 20 to 30 seconds using one probe or CO2 or curtain.

● Cores can be fired this way.

● Sodium silicate reacts with CO2 present in the model and produce a very hard ingredients or substance commonly known as silica gel.

Carbon-Dioxide Gas Molding

● The hard substance such as cement and helps in binding the sand grains.

● Molds and cores can be prepared therefore be used for pouring molten metal for the production of ferrous and non-ferrous casting both.

● The operation is fast, simple require semi-skilled worker.

● Gas evolution is significantly reduced after pouring the mold thus prepared.

● The process eliminates mold and core baking oven.

● Reclamation of sand used is difficult to process.