precision machining and manufacturing_precision machining and manufacturing

(3) The influence of mould making on the linear shrinkage rate of castings: a. The influence of wax injection temperature, wax injection pressure and pressure holding time on the size of investment mold is obvious in the wax injection temperature, followed by the wax injection pressure, and the pressure holding time is guaranteed After the investment is formed, it has little effect on the final size of the investment. b. The linear shrinkage rate of wax (mold) material is about 0.9-1.1%. c. When the investment mold is stored, there will be further shrinkage, and its shrinkage value is about 10% of the total shrinkage, but when stored for 12 hours, the investment mold size is basically stable. d. The radial shrinkage rate of the wax mold is only 30-40% of the lengthwise shrinkage rate. The wax injection temperature has a far greater influence on the free shrinkage rate than the hindered shrinkage rate (the preferred wax injection temperature is 57-59℃, The higher the temperature, the greater the shrinkage).