These processes include, molding is done most often with green sand. can be defined as a plastic mixture of grains of sand, clay, water, and other materials can be used for molding and . The sand is called “green” because of the moisture present and thus distinguish between dry sand. Following are the basic steps in the green-sand molding:
1. Preparing the pattern. Most are green-sand molding with plate game or cope and drag patterns. Loose patterns used are relatively small when projection type to be made. In simple hand shape the pattern is loosely placed on board mold and surrounded with appropriate-sized flask.
2. Making the mold. Molding requires the ramming sand around the pattern. Because the sand is packed, it develops strength and becomes rigid within the flask. Ramming may be done manually. Both cope and drag are shaped the same way, but the deal must make provision for sprue. These segments are gating systems simply channels the mold cavity to the entry of molten metal.
3. Core version. To fight and draw half the mold made and the pattern of withdrawal, set cores into the mold cavity to form the internal surfaces of the casting.
4. Final and weighting. With cores set, closed the deal and draw. Must tackle usually be weighted down or clamped to the draw to prevent it from floating when the metal is poured.
Because of the nature of the molding and shaping green sand-sand, the process has certain advantages and limitations. Pros:
1. Great flexibility as the production process. Mechanical equipment can be used for performing shape and its associated operations. Moreover, green sand can be reused many times by making it with water, earth and ether materials. The molding process can be quick and repetitive.
2. Usually the meat directly from a pattern way to model ready for pouring molding -sand is green.
3. Economy, green sand molding is usually the least costly method of molding.
Limits on the use of green-sand molding:
1. Some designs require solutions using other casting processes. Thin, long projections greencavity washed away by the molten metal or may not even be moldable. Sample cooling fins on the cylinder blocks air-cooled engine and head. There are plenty more needed then the model.
2. certain metals and some development castings defects if poured into molds containing moisture.
3. During the dimensional accuracy and surface finish green-sand casting to be adequate.
4. Large projection model more strength and resistance to corrosion than is available in green sand.