(1) The influence of the structure of the casting: a. The wall thickness of the casting has a large shrinkage rate, and the casting wall is thin and the shrinkage rate is small. b. The free shrinkage rate is large, and the hindered shrinkage rate is small.
(2) Influence of shell-making materials: The use of zircon sand, zircon powder, Shangdian sand, and Shangdian powder has a small expansion coefficient of only 4.6×10-6/℃, so it can be ignored.
(3) Influence of shell roasting: Due to the small expansion coefficient of the shell, when the shell temperature is 1150 °C, it is only 0.053%, so it can also be ignored.
(4) Effect of casting temperature: The higher the casting temperature, the greater the shrinkage rate, the lower the casting temperature, the smaller the shrinkage rate, so the casting temperature should be appropriate.
