What Does Draw Ratio Mean for Deep-Draw Tray Lamination?
Film thins locally as it stretches over the tray surface; the higher the draw ratio, the worse the thinning. Deep-draw lamination requires draw-ratio control and pre-compensated thickness.
Draw-Ratio Essentials
Clear definition
Draw ratio = formed area / flat area, determining thinning.
Predictable thinning
Local thinning roughly tracks the draw ratio — compensate proportionally.
Rupture risk
Beyond the film's elongation limit, rupture occurs.
Tooling synergy
Corner radii and draft angles lower the effective draw ratio.
Draw-Ratio Control Reference
Measure per tray geometry.
| Shallow trays | < 1.5, standard lamination |
|---|---|
| Mid-depth | 1.5–2.5, compensation needed |
| Deep-draw | > 2.5, thicker film + process optimization |
| PE elongation limit | 300%+ |
| PLA elongation limit | ~30–100% |
| Design guidance | Radii ≥ 5 mm, draft ≥ 5° |
Draw-Ratio FAQ
Where do deep-draw laminations fail?
Over-thinned corners and rupture, then wrinkles — fix with thickness compensation and larger radii.
Can we predict where it will break?
Yes — forming simulation predicts thinning distribution to guide film design.
Is PLA suitable for deep draws?
Its elongation is limited; prefer PP/PE or a lower-draw design.
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