Resin Shrink Rate
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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 represent the laminar flow. The chart below displays the typical mold shrink rates for the most commonly used resins.
| Resin Type | Shrink inch / inch |
| Polypropylene -unfilled | 0.015″ – 0.018″ |
| Polyethylene | 0.020″ – 0.025″ |
| ABS | 0.0035″ |
| HIPS | 0.0035″ |
| GPPS | 0.0035″ |
| Polycarbonate | 0.007″ |
| PC-ABS | 0.007″ |
| Acrylic | 0.003″ – 0.004″ |
| Nylon 6/6 (PA66) – Unfilled | 0.020″ |
| Nylon 6/6, 33% short glass | 0.0035″ |
| PBT | 0.015″ |
| Acetal (POM) | 0.020″ |
| Acetal Homopolymer | 0.018″ – 0.020″ |
| PVC (Rigid) | 0.0035″ |
| TPE (Santoprene) | 0.014″ – 0.018″ |
| Noryl | 0.005″ – 0.007″ |
| Noryl 30% glass filled | 0.001″ |
| TPU | 0.007″ – 0.010″ |
| Polysulphone | 0.007″ |