Solidification characteristics of metal liquid of machine tool castings

  There are three kinds of casting process: lost foam casting, sand casting and metal casting. Among them, metal casting has the fastest cooling rate, no eutectic platform appears on the cooling curve, the number of graphite in the metallographic structure is greatly reduced, and the radial casting of the machine tool casting is extended. A large number of fine primary and secondary carbides have significantly better hardness and impact toughness than the other two casting methods.

  The effects of lost foam casting and sand casting are relatively close. Before the eutectic reaction, the cooling curves of the two almost coincide, but the difference between the two increases from the eutectic reaction. Compared with sand casting, the reaction time of eclipse casting eutectic is relatively prolonged, and the cooling rate after eutectic reaction is relatively slow. Therefore, the eutectic matrix structure of the lost foam casting is coarse, the number of carbides is reduced, the amount of graphite is increased, and the corresponding hardness is obtained. And the impact toughness is reduced.

Solidification characteristics of castings of lost foam casting machine tools:

1. The cooling and solidification speed of the lost foam machine tool castings is slower than that of ordinary sand casting.

2. Lost foam casting is carried out under negative pressure, the cast steel is good, the casting cast iron parts will not appear to rise, the castings have strong self-feeding ability, and the shrinkage tendency of the castings is greatly reduced.

3. The casting mold of the lost foam casting machine has a slow cooling rate, and the casting is less affected by the casting mold. It is smaller than the clay sand casting type casting, so the casting has little stress and a small tendency to heat.