Among the total casting production, 60-70% of castings are produced using sand molds, and about 70% of them are produced using clay sand molds. The main reason is that sand casting has lower costs, simpler production processes, and shorter production cycles compared to other casting methods. So castings such as the engine cylinder block, cylinder head, and crankshaft of automobiles are all produced using the clay green sand process. When the wet mold cannot meet the requirements, consider using clay sand surface dry sand mold, dry sand mold, or other sand molds. The weight of castings cast with clay green sand can range from a few kilograms to tens of kilograms, while castings produced with clay dry mold can weigh tens of tons.
Generally speaking, for medium to large castings, cast iron can be produced using resin self hardening sand molds, and steel castings can be produced using water glass sand molds. Castings with precise dimensions and smooth surfaces can be obtained, but the cost is relatively high.
Of course, the precision, surface finish, material density, metallographic structure, mechanical properties, and other aspects of castings produced by sand casting are often poor. Therefore, when these performance requirements of castings are high, other casting methods should be used, such as investment casting (wax loss), die casting, low pressure casting, and so on. For heavy castings produced in small batches, manual molding is still an important method. For large castings produced in medium batches, resin self hardening sand molding and core making can be considered.
