Engineering Tools
Plastic Shrinkage & Mold Dimension
Shrinkage and density of common resins, and the mold cavity size for your part.
Calculator
- Mold cavity dimension
- 51 mm
- Range over the material's shrinkage
- 50.75–51.75 mm
Reference table
| Material | Chinese name | Shrinkage % | Typical % | Density g/cm³ | Notes |
|---|---|---|---|---|---|
| ABS | 丙烯腈-丁二烯-苯乙烯 | 0.3–0.8 | 0.55 | 1.05 | Handles, cap shells, buttons |
| PP | 聚丙烯 | 1–2.5 | 1.8 | 0.90–0.91 | Tip caps, sleeves, liners; shrinkage varies strongly with wall thickness |
| POM | 聚甲醛 | 1.5–3.5 | 2 | 1.41–1.42 | Runners, notches, latches; stiff and self-lubricating, keep walls uniform |
| PA66 | 尼龙 66 | 0.8–1.5 | 1.4 | 1.13–1.15 | Absorbs moisture; dry before molding |
| PA66 + 30% GF | 尼龙 66 + 30% 玻纤 | 0.2–0.8 | 0.3 | 1.37–1.39 | High-strength notches and runners; anisotropic shrinkage |
| PA6 + 30% GF | 尼龙 6 + 30% 玻纤 | 0.3–0.7 | 0.4 | 1.35–1.37 | As above |
| PC | 聚碳酸酯 | 0.5–0.7 | 0.6 | 1.20 | Transparent parts |
| TPE / TPR | 热塑性弹性体 | 1–2 | 1.5 | 0.9–1.1 | Soft-touch overmold; wide range, confirm with the resin supplier |
| TPU | 热塑性聚氨酯 | 1–1.2 | 1.1 | 0.97–1.24 | Elastomer |
| PVC | 聚氯乙烯 | 0.6–1.5 | 1 | 1.38–1.41 | — |
Notes
Cavity = part size × (1 + shrinkage). Shrinkage varies up to ±0.3% between suppliers, and glass-filled resins shrink differently along and across the flow. Use the chosen resin supplier's datasheet before cutting steel.
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