stainless steel precision casting

Stainless steel precision casting or investment casting, silica sol process. It is a casting process with little or no cutting, and an excellent process technology in the foundry industry. The surface quality is higher than other casting methods, and even complex, high temperature resistant and difficult to process castings that are difficult to cast by other casting methods can be cast by investment casting.

Because the heat-resistant alloy material is difficult to machine and the shape of the parts is complex, so that it cannot or is difficult to manufacture by other methods, so through the improvement of materials and processes, modern investment casting methods have achieved important development. This stainless steel precision casting process has been widely used in aviation, automobiles, machine tools, ships, internal combustion engines, gas turbines, telecommunication instruments, weapons, medical equipment and knives and other manufacturing industries, and is also used in the manufacture of arts and crafts.

The so-called investment casting process, simply put, is to use fusible materials (such as wax or plastic) to make a fusible model (referred to as investment mold or model), and coat it with several layers of special refractory coatings, which are dried and hardened. After forming an integral mold shell, the mold is melted from the mold shell with steam or hot water, and then the mold shell is placed in a sand box, filled with dry sand molding around it, and finally the mold is placed in a roasting furnace for high temperature. Roasting (for example, when a high-strength mold is used, the mold after demolding can be directly fired without molding), after the mold or mold is fired, molten metal is poured into it to obtain a casting.

The dimensional accuracy of investment castings is relatively high, generally reaching CT4-6 (CT10~13 for sand casting and CT5~7 for die casting). Of course, due to the complex process of investment casting, there are many factors that affect the dimensional accuracy of castings, such as mold The shrinkage of the material, the deformation of the investment mold, the linear change of the shell during heating and cooling, the shrinkage rate of the alloy, and the deformation of the casting during the solidification process, etc., so the dimensional accuracy of ordinary investment castings is high, but its Consistency still needs to be improved (castings with medium and high temperature waxes are much more dimensionally consistent).

When pressing the investment mold, a mold 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 high temperature-resistant special binder and refractory paint made of refractory material, which is painted and hung 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 due to the high dimensional accuracy and surface finish of investment castings, machining work can be reduced, but only a small amount of machining allowance can be left on the parts with higher requirements, and even some castings only Leave grinding, polishing allowance, can be used without machining. It can be seen that the use of investment casting method can save a lot of machine tool equipment and processing time, and greatly save metal raw materials.

Another advantage of the investment casting method is that it can cast complex castings of various alloys, especially superalloy castings. For example, the blade of a jet engine has a streamlined outline and an inner cavity for cooling, which can hardly be formed by machining processes. The investment casting process can not only achieve mass production and ensure the consistency of castings, but also avoid the stress concentration of residual knife lines after