Work out casting shrinkage instantly with clear inputs, formula shown and shareable results.
Metal contracts as it solidifies and cools, so the pattern must be made larger than the finished casting by the linear shrinkage allowance: about 1 percent for grey iron, 2 percent for steel and 1.3 percent for aluminium. Volumetric shrinkage is roughly three times the linear figure, which is what the risers must feed.
Pattern size
Pattern = casting dimension x (1 + linear shrinkage)
Volumetric
Volume shrinkage = (1 + linear)³ - 1
Pattern = casting dimension x (1 + linear shrinkage). Metal contracts as it solidifies and cools, so the pattern must be made larger than the finished casting by the linear shrinkage allowance: about 1 percent for grey iron, 2 percent for steel and 1.3 percent for aluminium.
Add it to the casting dimension first, then apply shrinkage to the total, so the as-cast surface has enough metal to machine away after it has contracted.
This calculator takes 3 inputs: Required casting dimension, Linear shrinkage allowance, Machining allowance. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.