What V opening should I use for stainless steel?

Ten times the material thickness, against eight times for mild steel. The wider opening lowers the force and the strain at the bend, which suits stainless's lower elongation.

Why does stainless need more tonnage than mild steel?

Higher tensile strength. The force formula uses tensile strength directly, and stainless at about 650 MPa needs roughly 1.4 times the force of mild steel at 450 MPa for the same opening.

How do I prevent marking when bending stainless?

Keep the tooling polished, widen the opening where possible, avoid dragging the sheet, and use urethane, film-faced or anti-mark dies for cosmetic surfaces.

Does stainless spring back more than mild steel?

Yes. Its higher yield strength means more elastic recovery at the same radius-to-thickness ratio, so the overbend correction is larger. Measure the first piece of each batch.

Can I bend all stainless grades on a press brake?

Most austenitic grades bend readily with the right opening and radius. Hardened or high-strength stainless grades need larger radii and may need stress relieving afterwards.

Press Brake Tooling for Stainless Steel: V, Force, Marking

Why is stainless steel harder to bend than mild steel?

Three reasons: it needs more force, it springs back further, and it work-hardens and galls at the tooling surface. The higher tensile strength raises the tonnage, the higher yield strength increases springback, and the material's tendency to stick to the tool marks the sheet.

What die opening should I use for stainless steel?

Ten times the thickness, against eight times for mild steel. The wider opening reduces the force and the strain at the bend, which matters because stainless has less elongation to spend than mild steel at the same radius.

Stainless against mild steel, same thickness
Aspect	Mild steel	Stainless steel
Die opening rule	8 × t	10 × t
Tensile strength used	≈ 450 MPa	≈ 650 MPa
Force for same opening	1.0 ×	≈ 1.4 ×
Springback	Lower	Higher, needs more overbend
Marking risk	Moderate	High, galling at the tool surface

How do I stop stainless marking at the bend?

Marking comes from galling: stainless welds microscopically to the tool and tears on release. Keep the tool surface polished, avoid dragging the sheet, and consider a film, a urethane pad or an anti-mark die for cosmetic work.

Polish the punch and die: a smooth surface gall less than a rough one.
Widen the opening where the part allows: less strain, less galling.
Anti-mark tooling: urethane or film-faced dies for visible surfaces.
Lubricate lightly where the process allows, and clean the tool between batches.

What about springback?

Stainless springs back further than mild steel at the same radius-to-thickness ratio, so the ram depth correction is larger. Overbend in small steps and measure the first piece; the springback calculator gives the compensation angle for the material and radius.

Springback grows as the radius-to-thickness ratio grows. A tight radius in thick stainless is the worst case for both force and angle recovery.

Related technical pages

Tooling by material

The material-by-material overview, including aluminium and high-strength steel.

Springback calculator

The compensation angle for material, thickness and radius.

Anti-mark tooling

Protecting a cosmetic face through a sharp bend or a hem.

Tooling for thick plate

The heavy-section end of the same question.

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Press brake tooling for stainless steel