Production of castings involves a large number of steps including casting design, pattern making, moulding, melting, pouring, shake out, fettling, inspection and finishing.
It is not uncommon for one or more of these steps to be performed unsatisfactorily due to use of defective material or equipment, carelessness of the operator or lack of skill.
Such unsatisfactory operations result in a defective casting which may be rejected at the final stage.
Since reclamation of defective castings is often costly and sometimes outright impossible, care should be taken to avoid the occurrence of the defects in the first instance.
It is therefore necessary to understand the various defects that occur in sand castings and the main factors that are responsible for their occurrence.