Shrinkage Calculator
A resin does not shrink by one number — it shrinks across a range, and filled grades shrink several times more across the flow than along it. Enter a dimension and a tolerance and this shows how much of that tolerance the resin takes before the machine, the tool or the gauge get a turn.
Semi-crystalline and high-shrink — the spread alone eats most of a tight tolerance.
Tight — the resin alone takes 91% of your tolerance
The resin takes most of the band on its own. Machine variation, tool wear and measurement all have to fit in what is left, and they will not fit quietly.
Cut the cavity at 12.9790 mm and the part lands between 12.6546 and 12.7454 mm — a spread of 0.0909 mm against your 0.1000 mm band.
Where these shrink numbers come from
They are typical published ranges for the resin family, and they are starting points rather than specifications. Shrinkage moves with grade, filler loading, wall thickness, gate size, melt and mold temperature and pack pressure. Replace both figures with the ones on your grade’s datasheet — the fields above are editable for exactly that.
The cavity figure assumes the steel is cut for the middle of the range, which is what a toolmaker does in the absence of better information. If you have molded the part before, the measured shrink beats any datasheet.