Bend radius and flange chart

Every bend has a smallest inside radius the material will take without cracking, and every flange has a shortest length the press brake can hold. Design to these and your part forms cleanly, with no surprises at the first article.

Minimum inside bend radius

As a multiple of material thickness (T):

Shortest flange

A flange needs enough length to sit across the die while it is formed. As a rule of thumb, make every flange at least 4 × T plus the inside radius, measured to the outside of the bend. Shorter flanges are possible with special tooling; ask us before you design them in.

Holes and cut-outs near a bend

• Keep holes at least 2.5 × T plus the bend radius from a bend, or they will stretch out of round.
• Keep holes at least 2 × T from an edge.
• Add a bend relief, a small notch at least T wide, where a bend meets an edge.
• Make holes at least the material thickness in diameter.

Press brake capacity

We form on press brakes up to 175 ton by 10 feet and 350 ton by 12 feet, with various tooling for complex geometries. For a long or heavy part, tell us the bend length and the thickness and we will check it against the tonnage needed.

Tolerances on formed parts

Typical, unless your drawing says otherwise: ±0.010 inch (±0.25 mm) on a flat cut feature, ±0.020 inch (±0.5 mm) across one bend, and ±1° on bend angles. Tolerances stack up across bends, so dimension critical features from one datum. Tighter tolerances are possible; put them on the drawing and we will quote to them.

See also the sheet metal gauge chart and designing sheet metal parts.