The production of stainless steel castings requires the use of investment casting technology. Today, Wujiang Blue Sky Precision Alloy Foundry Co., Ltd. talks with everyone about the investment casting process, as follows:

The so-called investment casting process, simply by using a fusible material (such as wax or plastic) to make a fusible model (referred to as investment or model), coated with several layers of special refractory coating, dried and hardened After forming a monolithic shell, the model is melted from the shell by steam or hot water, and then the shell is placed in a flask, filled with dry sand molding around it, and finally the mold is placed in a roaster at a high temperature. Calcination (for example, when a high-strength type shell is used, the demolded shell can be directly fired without styling), and the mold or shell is fired, and molten metal is poured therein to obtain a cast piece.

Investment castings have high dimensional accuracy, generally up to CT4-6 (sand casting is CT10~13, die casting is CT5~7). Of course, due to the complicated process of investment casting, there are many factors affecting the dimensional accuracy of castings, such as mold. The shrinkage of the material, the deformation of the investment mold, the change in the amount of the shell during heating and cooling, the shrinkage of the alloy, and the deformation of the casting during solidification, etc., so the dimensional accuracy of ordinary investment castings is high, but Consistency still needs to be improved (the dimensional uniformity of castings using medium and high temperature waxes is much higher).

When the investment mold is pressed, the molding having a high surface finish of the cavity is used, and therefore, the surface finish of the investment mold is also relatively high. In addition, the shell is made of a refractory paint made of a special binder and a refractory material which is resistant to high temperature, and is coated on the investment mold, and the inner surface of the cavity which is in direct contact with the molten metal has a high surface finish. Therefore, the surface finish of the investment casting is higher than that of the general casting, and generally reaches Ra.1.6~3.2μm.

The biggest advantage of investment casting is that because of the high dimensional accuracy and surface finish of the investment casting, the machining work can be reduced, but only a small amount of machining allowance is required on the parts, even some castings only The grinding and polishing allowance can be used without machining. It can be seen that the 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 process is that it can cast complex castings of various alloys, particularly casting high temperature alloy castings. For example, the blade of a jet engine, the streamlined profile and the cooling cavity, can hardly be formed by a machining process. The production by the investment casting process can not only achieve mass production, but also ensure the consistency of the castings, and avoid the stress concentration of the residual knives after machining.