In the process of casting, various casting defects may be formed on the surface and inside of the casting due to various reasons. Casting defects are the main causes of poor performance and shortened service life of castings. Therefore, we need to classify and study the characteristics of various casting defects, judge their causes and processes, and realize the prevention and elimination of casting defects. According to the current Chinese standard (gb5611-85), casting defects can be divided into the following eight categories according to their morphological characteristics:
- Fleshy casting defects (flash, burr, sand falling, etc.);
- Casting defects such as holes (pores, shrinkage porosity and shrinkage cavity);
- Crack casting defects (cold crack, white spot, cold shut, etc.);
- Surface casting defects (including sand inclusion defects and sand sticking defects);
- Incomplete casting defects (insufficient pouring, fire escape and mold leakage);
- Inclusion casting defects (sand holes and slag inclusions with metallic inclusions, cold beans and non-metallic inclusions);
- Composition and weight deviation and casting defects;
- Unqualified composition, structure and performance and casting defects.
This paper will focus on the formation and prevention of several kinds of casting defects, such as shrinkage porosity, porosity, sand inclusion and cracking, which are most common in the actual production of sand mold casting.