Every step in the metal casting process from mold making to heat treatment is done carefully to avoid problems with the strength, surface quality, mechanical properties and final dimensions of the finished casting. However, even careful castings should be inspected for quality control. Minor problems can occur unexpectedly and many castings have mechanical requirements that can be damaged by a hidden defect. Supervision and inspection ensure that the foundry and customers are assured of a quality casting.

Common casting defects and discontinuities

• Surface imperfections
• Insertion errors
• Molding and spillage defects
• Flashing at joining.
• Mold mismatch or mold slip
• Sand imbalance,
• Cold shots,
• Needle holes and air holes or gas porosity,
• Cooling defects
• Shrinkage porosity,
• Shrinkage gaps,
• Cooling deformation

Dimensional tolerance or surface quality issues can often be seen by visual inspection and measurement. Tests for mechanical properties can also be carried out easily. Some of the other problems like porosity and shrinkage gaps are in the casting. Test methods can be used to catch internal problems, so a dump will not unexpectedly fail under load. There are two main types of internal testing: destructive and non-destructive.