Material · Property data
Mould Shrinkage of Plastics – Comparison Table
The mould shrinkage describes how much a moulded part shrinks on cooling relative to the cavity. It is decisive for tool design. Semi-crystalline plastics (PE, PP, POM, PA) shrink markedly more than amorphous ones (ABS, PC, PMMA).
Mould shrinkage table (overview)
| Abbr. | Plastic | Shrinkage (%) | Character |
|---|---|---|---|
| PETG | PETG (copolyester) | 0.2–0.5 | amorphous (low) |
| PA66-GF30 | Polyamide 66, 30% glass fibre | 0.3–1 | semi-crystalline (higher) |
| PP-GF30 | Polypropylene, 30% glass fibre | 0.4–1 | semi-crystalline (higher) |
| PLA | Polylactic Acid (bioplastic) | 0.4–0.5 | semi-crystalline (higher) |
| PMMA | Poly(methyl methacrylate) (acrylic) | 0.5 | amorphous (low) |
| PVC-U | Rigid PVC (PVC-U) | 0.5 | amorphous (low) |
| TPU | Thermoplastic Polyurethane | 0.5–1.4 | semi-crystalline (higher) |
| ABS | Acrylonitrile Butadiene Styrene | 0.6 | amorphous (low) |
| PC | Polycarbonate | 0.6 | amorphous (low) |
| PA6 | Polyamide 6 (Nylon 6) | 1–1.4 | semi-crystalline (higher) |
| TPE | Thermoplastic Elastomer (SEBS) | 1.3–2.5 | semi-crystalline (higher) |
| PA66 | Polyamide 66 (Nylon 66) | 1.5–2 | semi-crystalline (higher) |
| PP | Polypropylene | 1.8–2 | semi-crystalline (higher) |
| PE-LD | Low-Density Polyethylene (LDPE) | 2–2.5 | semi-crystalline (higher) |
| PE-HD | High-Density Polyethylene (HDPE) | 2.2–2.8 | semi-crystalline (higher) |
| POM | Polyoxymethylene (acetal) | 2.2–2.4 | semi-crystalline (higher) |
Mould shrinkage (parallel–normal) in % to ISO 294-4, unfilled grades. Sources per value below.
Shrinkage compared
Reading shrinkage
Semi-crystalline plastics (PE, PP, POM, PA6/PA66) shrink most at ~1–2.8% and often anisotropically – risk of warpage. Amorphous plastics (ABS, PC, PMMA, PVC) shrink little and more uniformly (~0.2–0.7%). Glass fibres strongly reduce shrinkage in fibre direction (e.g. PA66-GF30 down to ~0.3%).
Frequently asked questions
What is mould shrinkage?
Mould shrinkage states by how many percent a moulded part shrinks on cooling relative to the cavity dimension. It is allowed for as oversize during tool design.
Which plastic shrinks most?
Semi-crystalline polyolefins and POM shrink most (HDPE, POM up to ~2.4–2.8%). Amorphous plastics like ABS, PC and PMMA are much lower at ~0.2–0.7%.
Why does glass fibre reduce shrinkage?
Glass fibres are dimensionally stable and restrain the polymer matrix from shrinking in the fibre direction. Shrinkage drops markedly along the flow, while normal to it stays higher – increasing anisotropy and warpage risk.
Sources per value
- PETG: 0.2–0.5 % — processing practice/datasheets (ISO 294-4)
- PA66-GF30: 0.3–1 % — processing practice/datasheets (ISO 294-4)
- PP-GF30: 0.4–1 % — processing practice/datasheets (ISO 294-4)
- PLA: 0.4–0.5 % — processing practice/datasheets (ISO 294-4)
- PMMA: 0.5 % — processing practice/datasheets (ISO 294-4)
- PVC-U: 0.5 % — processing practice/datasheets (ISO 294-4)
- TPU: 0.5–1.4 % — processing practice/datasheets (ISO 294-4)
- ABS: 0.6 % — processing practice/datasheets (ISO 294-4)
- PC: 0.6 % — processing practice/datasheets (ISO 294-4)
- PA6: 1–1.4 % — processing practice/datasheets (ISO 294-4)
- TPE: 1.3–2.5 % — processing practice/datasheets (ISO 294-4)
- PA66: 1.5–2 % — processing practice/datasheets (ISO 294-4)
- PP: 1.8–2 % — processing practice/datasheets (ISO 294-4)
- PE-LD: 2–2.5 % — processing practice/datasheets (ISO 294-4)
- PE-HD: 2.2–2.8 % — processing practice/datasheets (ISO 294-4)
- POM: 2.2–2.4 % — processing practice/datasheets (ISO 294-4)
Last updated: 2026-08-12 · Guide values for unfilled standard grades, ~23 °C. All data without warranty; filled compounds differ.