The purpose of investment setting expansion is to compensate for
The rationale for increasing setting expansion is that certain newer alloys, such as base metal, have a greater casting shrinkage than do the traditional noble metal alloys. Thus, higher expansion is required in the stone die to aid in compensating for the alloy solidification shrinkage.
Phillips 12th edition page no 191
Casting Shrinkage
Casting expansion
Wax elimination
Alloy melting