Performance indicators mainly include: the pattern material melting and solidification temperature interval, heat resistance, thermal expansion rate and shrinkage, strength, hardness, viscosity, liquidity, smearing and ash content, etc.General precision casting enterprise hard to examines the performance indicators.So, when choosing the supplier, as far as possible to choose some relatively perfect quality management system of formal enterprises, strictly to the supplier evaluation and confirmation.But, as one of the most important performance indexes of pattern material, shrinkage rate and can detect, shrinkage rate directly affects the dimension precision of casting and the quality of the shell.At present, the domestic circle pie sample line shrinkage method without considering the influence of wax mold structure on the shrinkage rate, best reference foreign stepped sample method is closer to the actual situation.