1. For the inner and outer sides of the casting and the reinforcing ribs, there should be a certain structural slope in the starting direction.
2. The convex plate of the casting and the casting body should not have large difference. It is best to take the same height. The convex plates with a short distance on the same plane are best to connect the whole convex part.
3. The shape of the casting should be simple, in order to strip. It should try to make the casting surface of the plane, and the number is smallest.
The use advantage of the precision casting
1. The precision casting can produce complicated parts, especially the blank with complex inner cavity.
2. The adaptability of the precision castings is very wide, and the metal materials commonly used in industry all can be cast.
3. The sources of raw materials are extensive. The price is low. Steel scrap, scrap, the shape and size of the chip castings are very close to the parts, reducing the cutting amount, which is a non-chip finish. Because of the good heat dissipation condition, the fluidity of metal liquid must be poor. The stress is also large, the thin wall is easy to appear white edge. The metal type can cast ductile iron and gray iron.
The heat treatment method of the precision casting
Because the purpose of precision casting is different, the heat treatment is very much, basically can be divided into two kinds. The first type is that the organizational structure will not change through the heat treatment or should not be changed. The second is the change in the basic organizational structure. The first heat treatment program is mainly used to eliminate the internal stress. The internal stress is caused by different cooling conditions and different conditions in the process of stainless steel casting. Tissue, strength and other mechanical properties are not changed significantly due to the heat treatment.
1. The soft annealing of precision casting is mainly to decompose carbide, reduce the hardness, and improve the handling characteristics. For ductile iron, the purpose is to obtain more ferritic structure.
2. Normalizing treatment: The main purpose is to obtain pearlite and sorbite microstructure to improve the mechanical properties of the stainless steel casting.
3. Quenching treatment: In order to obtain higher hardness or abrasion strength, at the same time to the very high surface wear resistance characteristics.
4. Surface hardening treatment: Mainly to obtain the surface hardened layer, at the same time obtain very high surface wear resistance characteristics.
5. Precipitation hardening treatment: The main reason is to obtain high strength and the elongation so as not to lead to drastic changes.