Common production process of stainless steel castings

Release time: 2019-04-28

The most common casting process for stainless steel castings is the investment casting process. Simply put, a fusible model (referred to as investment or model) is made of fusible materials (such as wax or plastic), and several layers of special The refractory coating is dried and hardened to form an integral shell, then the model is melted from the shell with steam or hot water, and then the shell is placed in a sand box, filled with dry sand molding around it, and finally the mold is cast Put it into a roasting furnace and undergo high-temperature roasting (for example, when a high-strength shell is used, the demolded shell can be directly roasted without molding), and after the casting mold or shell is roasted, 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 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 castings is high, but its Consistency still needs to be improved (castings with medium and high temperature waxes are much more dimensionally consistent).

When the stainless steel casting presses the investment mold, the mold with 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 prepared from refractory materials, which is coated 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.

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