What Are the Advantages of Investment Casting Technology?
1. Understand investment casting technology
Investment casting technology, also known as lost wax casting, includes processes such as pressing wax, repairing wax, tree assembly, dipping slurry, melting wax, casting molten metal, and post-processing. Lost wax casting is to use wax to make a wax mold of the part to be cast, and then coat the wax mold with slurry, which is a clay mold. After the clay mold is dried, put it in hot water to melt the internal wax mold. Take out the clay mold from the melted wax mold and fire it into a pottery mold. Once roasted, generally, a pouring port is left when making a clay mold, and then molten metal is poured from the pouring port. After cooling, the required parts are made. So, what are the advantages of investment casting technology?
2. Advantages of the investment casting technology
The dimensional accuracy of investment casting parts is relatively high, generally up to CT4-6 (CT10 to 13 for sand casting and CT5 to 7 for die casting). Of course, due to the complex process of investment casting technology, there are many factors that affect the dimensional accuracy of investment casting parts. For example, the shrinkage of the mold material, the deformation of the investment mold, the heat change of the shell in the heating and cooling process, the shrinkage rate of the alloy and the deformation of the casting during the solidification process, etc., so the dimensional accuracy of ordinary investment casting parts is relatively high, However, its consistency still needs to be improved (the size consistency of casting parts using medium and high temperature waxes should be improved a lot).
When pressing the investment mold, a pressure type with a high surface finish of the cavity is used, so the surface finish of the investment mold is also relatively high. In addition, 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 that is in direct contact with the molten metal has a high smoothness. Therefore, the surface finish of investment casting parts is higher than that of general casting parts, generally reaching Ra.1.6 to 3.2μm.
The biggest advantage of direct investment casting technology is that because investment casting parts have high dimensional accuracy and surface finish, it can reduce machining work, but only leave a little machining allowance on the parts with higher requirements. Even for some casting parts, only the grinding and polishing allowance are left, and it can be used without mechanical processing. It can be seen that the use of investment casting technology can greatly save machine tool equipment and processing man-hours, and greatly save metal raw materials.
Another advantage of investment casting technology is that it can cast complex casting parts of various alloys, especially high-temperature alloy casting parts. For example, the blade of a jet engine, streamlined profile and cooling cavity, which can hardly be formed by machining technology. The investment casting technology can not only achieve mass production, ensure the consistency of castings, but also avoid the stress concentration of residual knife marks after machining.