Casting is one of the basic processes of modern equipment manufacturing. The casting process can be divided into three basic steps, namely casting metal preparation, mold preparation, and casting processing. Casting metal refers to the metal material used for casting castings in the production of castings. It is an alloy in which metal elements are the main components and other metals or non-metal elements are added. It is usually called casting alloy, which mainly includes cast iron, cast steel, and cast non-ferrous alloy.
40%~70% of agricultural machinery and 70%~80% of machine tools are castings.
1. Usually, the metal solidifies too fast at this place, resulting in casting defects (joints);
2. Cracks caused by high temperatures.
The solution: Use low-strength investment materials, reduce the casting temperature of the metal as much as possible, and do not use alloys with low ductility and brittleness.
If this problem occurs, it may be due to material problems or poor mold opening or improper selection of process parameters. Try to control the proportion of waste not to exceed 30%. The mold retention time should not be too long, about 3s per mm of wall thickness, and ejection delay is not allowed. Long, generally 0.5-2s.
Reinstall the mold; increase the clamping force and adjust the die-casting machine to keep the movable and fixed mold mounting plates parallel to each other; add a support plate on the movable mold to increase the rigidity of the sleeve plate.
In order to be suitable for die casting, people add a lot of silicon to the aluminum alloy used for die casting. When the aluminum alloy condenses in the mold, the silicon will float on the surface to form a layer of silicon film that is very hard and wear-resistant. Some OEM designers use this feature to directly design the inner surface of the die casting hole as a bearing surface. This silicon surface layer is generally only 0.2 to 0.9 mm thick. With too much processing, the life of the bearing surface will be shortened.
1. The mark on the mold is not clear enough (the reason for the mold);
2. The markings on the mold are not clear. You can analyze whether the particle size of the following molding sand is fine enough and whether the strength is high enough;
3. The refractoriness of the mold and coating is not enough.
4. Another factor that is easily overlooked is the casting location of the casting mark. When determining the casting position, try to keep the casting mark on the bottom or side to avoid being on the top surface.