1. Preferential use of sand casting. According to statistics, in China or internationally, 60 to 70% of the total casting output is produced by sand molds, and about 70% of them are produced by clay sand molds. The main reasons are that sand casting has lower cost, simpler production process and shorter production cycle than other casting methods. Therefore, castings such as automobile engine cylinder blocks, cylinder heads, and crankshafts are produced using the clay wet sand process. When the wet mold can not meet the requirements, then consider using a clay sand surface dry sand mold, dry sand mold or other sand mold. The weight of the clay wet sand casting casting can range from a few kilograms up to tens of kilograms. Generally speaking, for medium and large castings, cast iron can be made of resin-reinforced sand molds, and steel castings can be produced with water glass sand molds. Castings with accurate dimensions and smooth surfaces can be obtained, but the cost is higher. Of course, the castings produced by sand casting are often inferior in terms of accuracy, surface finish, material density, metallographic structure, and mechanical properties. Therefore, when these castings require higher performance, other casting methods such as investment Wax) casting, die casting, low pressure casting, etc.
2. Low-pressure casting, die-casting, centrifugal casting and other casting methods are suitable for mass production due to the high price of equipment and molds. For small castings, horizontal parting or vertical parting can be used without box high pressure molding machine production line, solid molding production efficiency is high, and the floor area is also small; for middle pieces, various boxed high pressure molding machine production lines Punching the molding line to meet the requirements of fast and high-precision molding production lines. The core making methods can be selected from the core making methods such as cold core boxes, hot core boxes, and shell cores. Medium-sized large-scale castings can be considered using resin self-hardening sand modeling and core making. For heavy-duty castings produced in small batches, manual modeling is still an important method. Manual modeling can be flexible to meet various complex requirements, and does not require many process equipment. Water glass sand molds, VRH method water glass sand molds, ester water glass self-hardening sand molds, clay dry molds, resin self-hardening sand molds, and cement sand molds can be used; for heavy-duty castings produced in a single piece, the pit modeling method has low cost and rapid production . Multi-box modeling and split-box modeling are more suitable for mass-produced or long-term shaped products. Although molds, sand boxes, etc. have high initial investment, they can be compensated by saving modeling hours and improving product quality.