Views:17 Author:Site Editor Publish Time: 2021-04-20 Origin:Site
Investment casting is a casting process with little or no cutting. It is an excellent process technology in the foundry industry and has a wide range of applications. It is not only suitable for casting of various types and alloys but also the dimensional accuracy and surface quality of aluminum castings produced are higher than other casting methods. The complex, high-temperature resistant and difficult-to-process aluminum castings that are difficult to cast by other casting methods can be cast by investment casting.
Investment casting aluminum alloy parts have high dimensional accuracy, generally up to CT4-6 (sand casting is CT10~13, die casting is CT5~7). The process of aluminum alloy investment casting is complex, and many factors affect the dimensional accuracy of the casting, such as the shrinkage of the mold material, the deformation of the investment mold, the linear change of the shell in the heating and cooling process, the shrinkage rate of the alloy, and the solidification Deformation of castings in the process, etc. When pressing the investment mold, the pressure type with a high surface smoothness of the cavity is used, and the surface smoothness of the investment mold is also relatively high. Besides, the shell is made of a refractory coating made of a special high-temperature resistant adhesive and refractory material, which is coated on the investment mold, and the inner surface of the cavity directly in contact with the molten metal has a high smoothness. Therefore, the surface finish of investment castings is higher than that of general castings, generally reaching Ra.1.6~3.2μm.
The biggest advantage of investment casting aluminum alloy is that it has high dimensional accuracy and surface finish, so it can reduce machining work. It is enough to leave a small amount of machining allowance on the parts with higher requirements, and even some aluminum castings only leave grinding and polishing allowances, which can be used without mechanical processing. It can be seen that the use of the aluminum alloy investment casting method can greatly save machine tool equipment and processing man-hours, and greatly save metal raw materials.
Another advantage of the aluminum alloy investment casting method is that it can cast various complex castings, especially high-temperature alloy castings. For example, the blade of a jet engine, its streamlined profile, and cooling cavity, can hardly be formed by machining technology. The use of investment casting aluminum technology can not only achieve mass production, ensure the consistency of castings, but also avoid the stress concentration of residual knife marks after machining.