Q. How can we use of Shrinkage allowance?
Since metal shrinks on solidification and contracts further on cooling to room temperature, linear dimensions of the pattern is increased in respect of those of the finishing casting to be obtained. This is called "shrinkage allowance". It is given as mm/ m.
Typical values of shrinkage allowance for various metals re given below:
C.I. Malleable iron = 10mm/m
Brass, Cu, Al = 15mm/m
Steel = 20mm/m Zinc,
Lead = 25mm/m