ShrinkPro Shrinkage Calculator.

Mold Cavity Dimension = Desired Part Dimension x (1 + Shrinkage Rate). For example, a 100 mm part in ABS with 0.6 percent shrinkage needs a 100.6 mm mold cavity. The ShrinkPro calculator runs this math automatically across 30+ specific resin grades.

Yes, significantly. Unfilled PA6 shrinks at 0.7 to 1.5 percent. PA6 GF30 (30 percent glass-filled) shrinks at 0.3 to 0.6 percent in the flow direction. The fibers resist polymer contraction but only along their orientation, which causes anisotropic shrinkage.

Mold shrinkage is what happens before the part leaves the cavity, measured at 24 hours per ASTM D955. Post-mold shrinkage is additional shrinkage over the next days to weeks as stresses relax and crystallization completes. Nylons and acetal show the most post-mold shrinkage (0.2 to 0.5 percent).

Bulk shrinkage calculations are accurate to within 0.1 to 0.2 percent under controlled process conditions. Directional effects on glass-filled or asymmetric parts can vary by 0.3 to 0.5 percent and require moldflow analysis. For non-critical dimensions, calculator-based sizing is production-ready.

Yes. Wall thickness variation, flow length, gate location, and cooling channel layout all create local shrinkage differences. Thick sections shrink more than thin ones in the same part. This is why warpage exists. Family molds with mixed-thickness parts are notoriously hard to balance.