How much draft angle does an injection molded product need?

For a standard smooth wall, count on 1 to 3 degrees per side, with a design value of 1.5 to 2 degrees. Ribs and webs can use less (0.5 to 1 degree); deep boxes on the core side actually require more (2 to 3 degrees).

Can a surface be draft-free, i.e. perpendicular out of the mold?

Zero degrees is possible, but costly: polished surfaces, special coatings, or a slide mechanism enable small draft-free zones. That is a conscious, cost-based choice, not a standard approach.

Why does a texture require extra draft?

A textured surface (grain or etched texture) will stick in the mold if it is not drafted extra. Allow about 1 degree additional draft per 0.025 mm texture depth, on top of the basic draft. Therefore, always specify texture choice and draft together.

Design for Manufacturing / Draft Angles

DfM Deep dive

Draft angles: without draft, a product does not release cleanly from the mold

Every surface in the direction of demolding requires draft (draft angle). Without draft, the product scrapes over the mold steel upon ejection: white wear marks, high ejection forces, deformation and, over time, damaged steel.

Plastic shrinks onto the core, not away from the cavity. The core side (inside) therefore determines the ejection force and deserves the largest draft. Even small features like texts, logos, and ribs require draft on their flanks—these are often forgotten.

Draft angle teaching plate: a few degrees of draft allow the part to release freely from the mold

Indicative draft per situation

Situation	Draft per side
Standard smooth wall	1 to 3 degrees, design for 1.5 to 2
Absolute minimum (short, smooth, polished)	0.5 degree
Ribs and partitions	0.5 to 1 degree
Deep boxes and sleeves (core side)	2 to 3 degrees, plus consider venting
Fine etched texture	plus 1 degree extra
Coarse grain or leather texture	plus 1.5 to 2 degrees extra

Indicative; the mold maker calculates the definitive draft for each face.

Draft changes dimensions

A wall of 50 mm high with 2 degrees of draft tapers 1.75 mm in thickness. So determine early which dimension is leading (top, bottom, or middle) and communicate that explicitly on the drawing. This avoids later discussions about which dimension is the 'real' one.

Draft works closely with wall thickness and material choice: see the full DfM-pillar or go to wall thickness.

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