China has for casting defects and technical reasons related aspects of classification, the general classification of the following ways: The first is a bad design to make it work and design flawed because it produces is a part of a collapsed when reach this part of the time, tooling manufacture of casting a flawed product. The second is the material and melting, when the two are different when defects are inevitable, melting the metal and alloy steel products manufacturing, rational performance and shrinkage is relatively large, the thermal cracking will great, when the increase in internal and external defects, casting techniques can also cause mistakes. One aspect of casting defects caused by technical knowledge, then the cracks and holes in it? The probability of the defect can be used sand step operation, and the shape of the defect classification negligent waste casting defects. Such as forgetting to lower the weight and ultra-poor parts of the core, carrying the box using the case of defects lead to trachoma, moderate control is king.