Castings

Castings are metal forming objects obtained by various casting methods, that is, the smelted liquid metal is injected into the pre-prepared mold by pouring, pressing, inhaling or other casting methods, and after cooling, grinding and other subsequent processing means, the object is deeply affected by the shape, size and performance. Metal liquid forming is often called casting, casting forming technology has a long history. As early as 5,000 years ago, our ancestors were able to cast red copper and bronze products. Casting is a widely used metal liquid forming process. It is a method of pouring liquid metal into the mold cavity, and after cooling and solidifying, obtaining the blank or part with definite shape. The proportion of liquid forming parts in machinery and equipment is very large, and the liquid forming parts in machine tools, internal combustion engines, mining machinery and heavy machinery account for 70% to 90% of the total weight; 50%~70% in cars and tractors; It accounts for 40% to 70% of agricultural machinery. The liquid forming process can be so widely used because it has the following advantages: (1) It can produce a blank with a very complex inner cavity. Such as various boxes, machine tool bed, cylinder body, cylinder head, etc. (2) Large process flexibility and wide adaptability. The size of the liquid forming part is almost unlimited, its weight can be from a few grams to several hundred tons, and its wall thickness can be from 0.5mm to about 1m. Any metal material that can be dissolved into liquid in industry can be used for liquid forming. For cast iron with poor plasticity, liquid forming is a practical and innovative way to produce its blanks or parts. (3) The cost of liquid forming parts is low. Liquid forming can directly use waste parts and chips, and the equipment cost is low. At the same time, the liquid forming part processing allowance is small, saving metal. However, the process of metal liquid forming is many, and it is difficult to accurately control, which makes the casting quality is not stable enough. Compared with forgings of the same material, the structure of liquid forming is loose and the grain is coarse