Preheating requirements of aluminum castings and rational use of aluminum casting molds
Aluminum castings require preheating before use. The aluminum mold must be preheated to a certain temperature before use. Preheating can extend the life of the mold.
Aluminum castings require preheating before use. The aluminum mold must be preheated to a certain temperature before use. Preheating can extend the life of the mold. Typically, preheating uses electrical or induction heating. The preheating temperature is controlled at 250℃～300℃. It can be used after keeping warm for about 0.5h. It is forbidden to use molten metal to directly preheat the mold, because the cold mold is in direct contact with the hot liquid metal and will inevitably be thermally shocked, which will lead to thermal corrosion and accelerate cracking and spalling caused by thermal fatigue.
In the process of manufacturing aluminum castings, the surface treatment quality of the mold cavity can be effectively improved. There should be no obvious deep machining tool marks on the surface of the mold cavity to prevent the mold from cracking due to stress concentration during the mold finishing process. The surface of the cavity should be effectively polished and ground, so that the surface roughness of the cavity should be controlled below 0.8μm.
In continuous production, the temperature of aluminum casting molds tends to rise. Excessive temperatures will not only cause boulders in the liquid metal, but also slow down the cooling rate of the casting, resulting in coarser grains and lower quality aluminum castings. Therefore, when the temperature of the cast aluminum mold is too high, cooling measures should be taken. Compressed air or water is usually used for cooling. Cast aluminum molds are usually designed with cooling systems to ensure the thermal balance of the mold.
After the cast aluminum mold is used, the mold cavity should be cleaned in time to a certain extent to effectively remove the residual aluminum. After cooling, anti-rust treatment should be carried out and put into warehouses for centralized management so that they can be used again. At the same time, by grasping the relevant links of mold design, manufacture, use, maintenance, management, etc., the service life of cast aluminum molds can be effectively extended, thereby reducing the cost of motor manufacturing.