Resin Mold Shrink Rate

All resins have different shrink rates depending on resin family, amorphous vs. crystalline materials, mold design, and also depending on processing conditions (cycle time and temperatures) as well as part design (shape and wall thickness). Resin also shrinks differently depending on the direction of flow, with (laminar) or against (transverse). The values below represnt the laminar flow. The chart below displays the typical mold shrink rates for the most commonly used resins.

»Printable Resin Mold Shrink Rate


Resin TypeShrink inch / inch
Polypropylene -unfilled0.015" - 0.018"
Polyethylene0.020" - 0.025"
ABS0.0035"
HIPS0.0035"
GPPS0.0035"
Polycarbonate0.007"
PC-ABS0.007"
Acrylic0.003" - 0.004"
Nylon 6/6 (PA66) - Unfilled0.020"
Nylon 6/6, 33% short glass0.0035"
PBT0.015"
Acetal (POM)0.020"
Acetal Homopolymer0.018" - 0.020"
PVC (Rigid)0.0035"
TPE (Santoprene)0.014" - 0.018"
Noryl0.005" - 0.007"
Noryl 30% glass filled0.001"
TPU0.007" - 0.010"
Polysulphone0.007"