Manufacturing & engineering
Draft angle
Definition
A draft angle is a slight taper on faces parallel to the mold's pull direction, so a molded or cast part can release from the tool. Missing draft is one of the most common reasons a plastic part design is sent back by a molder.
Also known as: draft, mold draft
Updated
How much draft#
The Protolabs molding guide gives 1 to 2 degrees as a common starting point, with more draft for textured surfaces. The molder's recommendation for your material and finish should win over any general rule.
CAD tools add draft as a feature. Onshape's Draft feature applies a draft angle to selected faces or a parting line to help pull a part from a mold, and a separate draft analysis shows faces that still lack it.
Sources
Related terms
DFM
DFM is the practice of shaping a part so it can be made reliably and economically with the intended process. It covers choices such as wall thickness, draft, tool access, bend radii, hole sizes, and tolerances the supplier can actually hold.
Tolerance
A tolerance is the allowed variation from a nominal dimension, such as 10.00 ± 0.05 mm. Tolerances drive fit, cost, and inspection, and they have to be specified deliberately because a CAD model on its own stores only nominal sizes.