Draft angle
also: draft · taper
A slight taper on the walls of molded or cast parts so they release cleanly from the mold; missing draft causes scuffing, sticking and tooling problems.
Walls parallel to the direction the mold opens drag against the steel as the part is ejected, causing scratches, distortion and stuck parts. A small taper solves it. Common design guidance is roughly 1–2° on smooth surfaces, with about 0.5° as a practical minimum where the design allows, and more on textured surfaces; published guides add roughly 1–1.5° per 0.025 mm (0.001 in) of texture depth.
Draft affects the design more than it looks: tall walls lose noticeable thickness from top to bottom, mating parts must account for it, and bosses, ribs and snap fits need it too.
Where it bites: CAD models without draft, prototyped by 3D printing or machining, look fine until the toolmaker adds draft, which changes fits and appearance late in the project.
Founder takeaway
Add draft from the first production-intent CAD model and confirm the values with your toolmaker for the chosen material and texture.
sources
engineer review pending