Injection Molding Shrinkage Calculator
Cavity size for a target part dimension, by polymer shrink rate.
Amorphous polymers (ABS, PC) shrink ~0.6%; semi-crystalline (PP, POM, PA) 1.5–2.5% — crystallization packs chains tighter. Glass fill cuts shrink but makes it ANISOTROPIC: different along vs across flow.
Formula
Injection Molding Shrinkage Calculator is a free molding shrinkage for design engineers, metallurgists and QA inspectors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Injection Molding Shrinkage Calculator
Cavity size for a target part dimension, by polymer shrink rate. The calculation implements cavity = part/(1 − shrink%) (Polymer datasheets; injection molding handbooks). Amorphous polymers (ABS, PC) shrink ~0.6%; semi-crystalline (PP, POM, PA) 1.5–2.5% — crystallization packs chains tighter. Glass fill cuts shrink but makes it ANISOTROPIC: different along vs across flow.
How to use Injection Molding Shrinkage Calculator
- 1Enter Target part dimension in mm.
- 2Enter Polymer (1 ABS (0.6%) · 2 PC (0.6%) · 3 PP (1.5%) · 4 POM (2.0%) · 5 Nylon 66 (1.5%)).
- 3Read Cavity dimension, Shrinkage applied instantly — no submit button needed.
- 4Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Injection Molding Shrinkage Calculator?
- ✓Implements the standard formula — cavity = part/(1 − shrink%)
- ✓Reference cited on-page: Polymer datasheets; injection molding handbooks
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Injection Molding Shrinkage Calculator use?+
It computes cavity = part/(1 − shrink%), per Polymer datasheets; injection molding handbooks. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Amorphous polymers (ABS, PC) shrink ~0.6%; semi-crystalline (PP, POM, PA) 1.5–2.5% — crystallization packs chains tighter. Glass fill cuts shrink but makes it ANISOTROPIC: different along vs across flow.
Where do the material property defaults come from?+
Defaults are standard handbook values (ASM, manufacturer datasheets, the cited standard). Always substitute certified values from your material's test certificate for critical work.
Is the Injection Molding Shrinkage Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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