(5) the influence of shell roasting: due to the shell of the small expansion coefficient, when the shell temperature of 1150 ℃, is only 0.053%, thus can be neglected.(6) the influence of pouring temperature, the higher the pouring temperature, the shrinkage rate, the greater the pouring temperature is low, the smaller the shrinkage rate, thus pouring temperature should be appropriate.Understanding these factors help reduce mistakes when he worked in precision casting and so on the job must be accurate data for efficient work.Font > a. materials of carbon content is higher, the line of the smaller shrinkage rate, the lower the carbon content, the line, the greater the shrinkage rate.B. common material casting shrinkage rate is as follows: casting shrinkage ratio K = (LM - LJ)/LJ x 100%, LM for the cavity dimension, LJ for casting size.K by the following factors: the wax models K1, K2, alloy casting structure types K3, K4 pouring temperature.