Second, at the time of repair of precision casting wax mold, we should pay attention to, all kinds of precision casting wax mold surface defect is repaired, flash, parting line is clean;According to the technological requirements, the examination of the size, shape, should use the fixture fixture;When repairing mold, in accordance with requirements cannot damage the wax models;Wax crumbs under repair should be put in dish in, keep the workbench and clean;To timely on the "identity card" logo.Three, the influence of the material for precision casting parts:Line 1, material of carbon content is higher, the smaller shrinkage rate, the lower the carbon content, line, the greater the shrinkage rate.2 common materials, precision casting, 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.