The improvement of casting quality will lead to the reduction of machining allowance and defect. As a result, certain precision castings of heat-resistant steel, which were previously thought to be qualified but which were torsion cast in air or vacuum, are now judged to be scrap. Typical examples of this condition are surface defects in heat - and corrosion-resistant steel castings, a defect formerly acceptable as "corrosion".

In the actual production, casting defects often need to be analyzed, the purpose is to find out the cause of defects, in order to take measures to prevent. For precision casting designers, understanding the product defects and their causes is helpful to correctly design the casting structure and properly formulate the technical requirements according to the actual conditions of casting production.

　　There are many defects in precision casting parts, and the defects and their causes are very complicated. Sometimes it can be seen that there are many defects caused by different reasons in the same casting, or the same reason may cause many defects in different production conditions.

Whether precision casting parts with defects are designated as waste products must be determined according to the purpose and requirements of the casting, as well as the location and severity of defects. In general, slight defects, can be used directly; Medium defect, which can be used after repair; If there are serious defects, they can only be scrapped.