Investment casting technology

Precision castings with high dimensional accuracy and small appearance roughness. It is suitable for investment casting valve body castings with complex structure. The dimensional accuracy of precision castings is affected by various factors such as casting structure, casting material, mold production, shell production, baking and pouring. In any stage of setting, unscientific operation can change the shrinkage rate of the casting, resulting in errors between the dimensional accuracy of the investment casting oven bars and the regulations. The following are the factors that lead to defects in the dimensional accuracy of precision castings:

(1) the impact of casting structure: a. Casting thickness, shrinkage rate, thin walls, shrinkage rate is small. b. Impede shrinkage rate is small arbitrary shrinkage rate is large.

(2) the impact of casting materials: a. The greater the carbon content, the smaller the line shrinkage, the lower the carbon content, the higher the line shrinkage. b. Forging shrinkage general materials are as follows: forging shrinkage K = (LM-LJ)/LJ × 1, LM cavity specifications, LJ casting specifications. K wax mold is affected by the following factors: K1. casting construction K2. alloy type K3. pouring temperature K4.

(3) the influence of casting temperature:the greater the pouring temperature, the higher the shrinkage rate, the lower the pouring temperature, the smaller the shrinkage rate, the pouring temperature as high as possible.