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Resin Mold Shrink-Rate Chart
All resins have different shrink rates depending on the plastic family. Amorphous vs. crystalline plastics, tooling design, process conditions (cycle temperature and time), along with part design (wall thickness and wall consistency) all affect shrinkage — and materials shrink differently with the direction of flow. The chart below presents typical shrinkage rates for commonly used plastics.
| Resin Type | Shrink (inch/inch) |
|---|---|
| Polypropylene — Unfilled | .015"/.018" |
| Polyethylene | .020"/.025" |
| ABS | .0035" |
| HIPS | .0035" |
| GPPS | .0035" |
| Polycarbonate | .007" |
| PC-ABS | .007" |
| Acrylic | .003"/.004" |
| Nylon 6/6 — Unfilled | .020" |
| Nylon 6/6 (33% Short Glass) | .0035" |
| PBT | .015" |
| Acetal (POM) | .020" |
| Acetal Homopolymer | .018"/.020" |
| PVC Rigid | .0035" |
| TPE Santoprene | .014"/.018" |
| Noryl | .005"/.007" |
| Noryl (30% Glass Filled) | .001" |
| TPU | .007"/.010" |
| Polysulfone | .007" |