Craft of gravity casting and pressure casting
Gravity casting refers to the process of injecting molten metal into the mold under the action of the earth's gravity, also called casting. The generalized gravity casting includes sand casting, metal casting, investment casting, mud casting, etc.; the narrow meaning of gravity casting refers specifically to metal casting
Pressure casting refers to the process of injecting molten metal into the mold under the action of other external forces (excluding gravity). Die casting in a broad sense includes pressure casting and vacuum casting of die casting machines, low pressure casting, centrifugal casting, etc.; pressure casting in a narrow sense refers to metal die casting of die casting machines, referred to as die casting.
The characteristics of gravity casting are:
1. There are few pores inside the casting and can be heat treated. After heat treatment, the strength of the product can be greatly improved, even exceeding that of the die-cast product. There are few pores inside the casting.
2. The product has low compactness. Relying on liquid self-weight molding, the compactness of the product is lower than that of die-casting, and its strength is slightly worse, but its elongation is lower than that of the product.
3. The surface finish of the product is not high. After cooling and shrinking, the cast product easily forms pits similar to shot blasting.
4. Slow filling and low production efficiency. Its production efficiency is only about a quarter of that of high-pressure casting, resulting in high product costs.
5. The mold life is longer than that of die casting, and the mold cost is low.
6. The process is relatively simple.
7. Not suitable for producing thin-walled parts.