Higher requirements for casting quality lead to reduced machining allowances and fewer defects. Therefore, certain heat-resistant steel precision castings cast in air or vacuum that were previously considered acceptable are now classified as rejects. A typical example of this situation is surface defects on heat-resistant and corrosion-resistant steel castings, a type of defect previously known as “corrosion” that was once acceptable.

In actual production, it is often necessary to analyze casting defects in order to identify the causes and take preventive measures. For precision casting designers, understanding product defects and their causes helps in correctly designing casting structures and appropriately formulating technical requirements based on actual casting production conditions.

Precision castings have many types of defects, and the causes are very complex. Sometimes multiple defects caused by different reasons may appear on the same casting, or the same cause may lead to multiple defects under different production conditions.

Whether a precision casting with defects is classified as a reject must be determined by the casting’s intended use and requirements, as well as the location and severity of the defects. Generally, castings with minor defects can be used directly; those with moderate defects may be used after repair; those with severe defects must be scrapped.