Draft Angle Calculator for Injection Molding
Introduction
This draft angle calculator helps you determine the correct draft angle for injection molded parts based on part height, material, and surface finish.
Proper draft is critical to avoid sticking, scratches, and mold damage during ejection.
🔥 Quick Design Rules
- Minimum draft: 1° per side
- Add more draft for textured surfaces
- Deep parts require more draft
- Poor draft = ejection problems + part damage
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Draft Angle Calculator for Injection Molding
Estimate the recommended draft angle for injection molded parts based on wall height, surface finish, texture, and material behavior.
Recommended Draft
Why this recommendation?
DFM warnings
How to improve the design
Draft angle is only one part of moldability. Wall thickness, ribs, bosses, shutoffs, texture, parting line, and ejection strategy should all be reviewed before tooling release.
Engineering Explanation
Draft angle is required to allow parts to release from the mold without friction damage.
Without proper draft:
- parts stick to the mold
- ejector force increases
- surface finish is damaged
Key factors:
- part height
- surface finish
- material shrinkage
- texture depth
Design Guidelines Table
| Surface Finish | Recommended Draft |
|---|---|
| Polished | 0.5° – 1° |
| Standard | 1° – 2° |
| Textured | 2° – 5°+ |
Common Mistakes
- Using zero draft
- Ignoring draft on internal walls
- Not increasing draft for texture
- Forgetting draft on ribs and bosses
Real Manufacturing Example
A housing with 0.5° draft and textured surface caused sticking and required tool modification.
Increasing draft to 3° solved the issue without redesigning the part.
Design Checklist
- Is draft applied to all vertical walls?
- Is draft increased for textured areas?
- Is part height considered?
- Is draft aligned with mold opening direction?
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