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 high-temperature-resistant special 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 castings is higher than that of general castings, generally reaching Ra.1.6~3.2μm.
The biggest advantage of investment casting is that because investment castings have high dimensional accuracy and surface finish, machining work can be reduced. It is enough to leave a little machining allowance on the parts with higher requirements, and even some castings only Leave a grinding and polishing allowance, and it can be used without mechanical processing. It can be seen that the use of investment casting method can save a lot of machine tool equipment and processing man-hours, and greatly save metal raw materials.
Another advantage of the investment casting method is that it can cast complex castings of various alloys, 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. Production with investment casting process can not only achieve mass production, ensure the consistency of castings, but also avoid the stress concentration of residual knife marks after machining.
As a stainless steel foundry, we know that the precision of castings obtained by various casting methods is different, the initial investment and productivity are also inconsistent, and the final economic benefits are also different. Therefore, in order to be more, faster, better, and less expensive, we should take all aspects into consideration. A preliminary cost estimate should be made for the selected casting method to determine the casting method that has high economic benefits and can guarantee the requirements of the casting.