【Casting】 Casting is a kind of metal thermal processing technology that human beings grasped earlier and is one of the basic processes of modern machinery manufacturing industry. Casting blanks achieve near-molding and free machining or a small amount of machining, reducing costs and reducing time to some extent.
Metal casting involves injecting a molten metal into a hollow mold made of a high temperature resistant material and condensing to obtain a product of the desired shape; the resulting product is a casting.
One, gravity casting | Gravity Casting
It refers to the process in which the molten metal is injected into the mold under the action of the gravity of the earth. It is also called casting. The metal liquid is generally poured into the gate manually, and the product is filled with cavity liquid, gravity, cooling, and mold opening.
Gravity casting has the following advantages: simple process, low mold cost, less internal porosity, heat treatment, etc. However, it has poor compactness and poor strength. It is not suitable for production of thin-walled parts, low surface finish, low production efficiency and high cost.
Second, pressure casting (die casting) | Die Casting
Under the effect of high pressure, a liquid or semi-liquid metal is filled into a die-casting (die-casting mold) cavity at a high speed, and the method of forming and solidifying a zinc alloy die under pressure.
High-pressure casting can be quickly filled, high production efficiency, product compactness, high hardness, good surface finish, can produce relatively thin wall thickness parts; at the same time due to the use of high-pressure air for filling, the internal gas involved in more, easy Air holes are formed inside the product. Therefore, heat treatment (diffusing the internal gas during heat treatment, resulting in bulging or cracking of the product) and post-processing (excessive throughput) can be avoided (avoiding the penetration of a dense layer on the surface to expose subcutaneous pores, Caused scrapping of zinc alloy die castings).