The improvement of the quality of the products by the steel casting manufacturers will lead to the reduction of machining allowances, especially the reduction of defects. There are some reasons that can cause the product to become scrap. This situation is the cause, most of which are due to surface defects in the castings, which used to be called "corrosion" defects.

In the actual girth gear process, it is necessary to frequently analyze the defects, find the reasons for the defects, and take corresponding measures to implement them. In particular, designers need to understand the causes of defects in castings, and can correctly design the structure of the product when designing. Combining the actual conditions of product processing, the corresponding technical requirements can be formulated to reduce the occurrence of defects.

If there are more defects in the product, the causes will be more complicated. Sometimes defects caused by different reasons or multiple types of defects caused by one cause will appear in the product. Whether or not the defective casting is located as a waste product needs to be determined according to the purpose of the casting and the location and severity of the defect.