What factors will affect the precision of stainless steel investment casting?

At present, the manufacturing process of stainless steel precision casting suppliers in the world has developed rapidly and been widely used. From the current situation, the future development trend of this process is that the casting products will become more and more close to the parts and components. The traditional precision castings are only used as blanks, which is no longer suitable for the rapid response of the market. The complexity and quality level of parts and components are getting higher and higher, R&D means are getting stronger and stronger, and professional cooperation is beginning to emerge. The application of CAD, CAM and CAE has become the main technology of parts and components product development. According to the current development, the casting technology has a wide range of applications, and its future development prospects are quite broad.

In general, the dimensional accuracy of stainless steel investment casting accessories is affected by many factors, such as casting structure, casting material, mold making, shell making, baking, pouring, etc. Any unreasonable setting and operation of any link will change the shrinkage rate of the casting, resulting in deviation between the dimensional accuracy of the casting and the requirements. The following factors can cause dimensional accuracy defects of precision castings:

(1) Influence of investment casting structure: a. Casting wall thickness, large shrinkage, thin casting wall, small shrinkage. b. The free shrinkage is large, and the hindered shrinkage is small.

(2) Influence of investment casting material: a. The higher the carbon content in the material, the smaller the linear shrinkage; the lower the carbon content, the greater the linear shrinkage. b. The casting shrinkage of common materials is as follows: professional stainless steel precision casting shrinkage K=(LM-LJ)/LJ × 99.9%, LM is the cavity size, LJ is the casting size. K is affected by the following factors: wax mold K1, casting structure K2, alloy type K3, and pouring temperature K4.

(3) Influence of mold making on linear shrinkage of precision castings: a The wax injection temperature, wax injection pressure and holding time have obvious effects on the size of the investment mold, followed by wax injection pressure. The holding time has little effect on the final Z size of the investment mold after ensuring the investment molding. b. The linear shrinkage of wax (mold) is about 0.9-1.1%. c. When the investment mold is stored, it will further shrink, and its shrinkage value is about 10% of the total shrinkage. However, after 12 hours of storage, the size of the investment mold is basically stable. d. The radial shrinkage rate of wax mold is only 30-40% of the shrinkage rate in the length direction. The influence of wax injection temperature on the free shrinkage rate is far greater than that on the blocked shrinkage rate (the better wax injection temperature is 57-59 ℃, the higher the temperature is, the greater the shrinkage rate will be).