The reasons why casting manufacturers can cause insufficient precision in precision casting specifications:
(1) The impact of precision casting structure: a. The wall thickness of the casting has a high shrinkage rate, while the wall thickness of the casting is thin and the shrinkage rate is low. b. The free shrinkage rate is high, while the hindrance shrinkage rate is low.
(2) The impact of precision casting materials: a. 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. b. The casting shrinkage of common materials is as follows: casting shrinkage K=(LM LJ)/LJ100%, LM is the cavity specification, and LJ is the casting specification. K is affected by the following reasons: wax mold K1, casting structure K2, alloy type K3, and pouring temperature K4.

(3) The influence of mold making on the linear shrinkage rate of precision castings: a. The impact of wax injection temperature, wax injection pressure, and holding time on the investment mold specifications is most significant, with wax injection temperature being the most significant. In addition, the impact of wax injection pressure and holding time on the final investment mold specifications is not significant after ensuring the investment mold is formed. b. The linear shrinkage rate of wax (mold) material is about 0.9-1.1%. c. When the mold is stored, further shrinkage will occur, with a shrinkage value of approximately 10% of the total shrinkage. However, after 12 hours of storage, the mold specifications are generally stable. d. The radial shrinkage rate of wax molds is only 30-40% of the shrinkage rate in the length direction, and the impact of wax injection temperature on the free shrinkage rate far exceeds the impact on the hindered shrinkage rate (suitable for wax injection temperature of 57-59 ℃, the higher the temperature, the greater the shrinkage).
(4) The impact of shell making materials: The use of zircon sand, zircon powder, Shangdian sand, and Shangdian powder can be ignored due to their small expansion coefficient, which is only 4.610-6/℃.
(5) The effect of shell baking: Due to the small expansion coefficient of the shell, when the shell temperature is 1150 ℃, it is only 0.053%, which can also be ignored.
(6) The impact of pouring 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.
The above is the relevant content introduced by casting and processing manufacturers, hoping to be helpful to everyone.