There are many factors that can cause dimensional accuracy defects in stainless steel precision forgings, and the editor has compiled what is currently known to the public：
1. The influence of forging structure
Forging wall thickness, high shrinkage rate, thin forging wall, low shrinkage rate
High free shrinkage rate, low hindrance shrinkage rate
2. The influence of forging material
The higher the carbon content in the material, the smaller the linear shrinkage rate. The lower the carbon content, the greater the linear shrinkage rate
The casting shrinkage rate of common materials is as follows: casting shrinkage rate K=(LM-LJ)/LJ x 100%, LM is the cavity size, LJ is the forging size
3. The influence of mold making on the linear shrinkage rate of forgings
The influence of wax injection temperature, wax injection pressure, and holding time on the size of the investment mold is most obvious at wax injection temperature, followed by wax injection pressure. Holding time has little effect on the final size of the investment mold after ensuring its formation.
The linear shrinkage rate of wax (mold) material is about 0.9-1.1%
When the investment mold is stored, further shrinkage will occur, with a shrinkage value of about 10% of the total shrinkage. However, after 12 hours of storage, the size of the investment mold is basically stable
The radial shrinkage rate of wax molds is only 30-40% of the length direction shrinkage rate. The influence of wax injection temperature on the free shrinkage rate is much greater than on the hindered shrinkage rate (the optimal wax injection temperature is 57-59 ℃, and the higher the temperature, the greater the shrinkage)
4. The influence of shell making materials
Using zircon sand, zircon powder, Shangdian sand, and Shangdian powder, due to their small expansion coefficient of only 4.6 × 10-6/℃, they can be ignored
5. The influence of casting temperature
The higher the pouring temperature, the greater the shrinkage rate. The lower the pouring temperature, the smaller the shrinkage rate. Therefore, the pouring temperature should be appropriate
6. The influence of shell roasting
Due to the small expansion coefficient of the shell, when the shell temperature is 1150 ℃, it is only 0.053%, so it can also be ignored.