Bend Radius

Bend radius selection is one of the most important decisions in sheet metal design because it directly impacts whether a part will crack, springback excessively, or form cleanly. The minimum achievable inside radius depends on the material type (mild steel is more forgiving than stainless or aluminum alloys), the sheet thickness, and the direction of the bend relative to the rolling grain.

A general rule of thumb is that the minimum bend radius should equal the material thickness for mild steel, but harder alloys may require 2x or 3x thickness to avoid fracture. Press brake operators control bend radius primarily through punch tip selection, a sharper punch tip produces a tighter radius, while a larger radius tip produces a gentler curve.

When designers specify radii tighter than the material can handle, the result is cracking on the outside of the bend that compromises structural integrity.