How to Choose Press Tonnage for Your Stamping Part (63T to 500T)

The 4 inputs you need before quoting a part

Before we can recommend 110T, 250T or 500T, four numbers go on the table:

Material type and grade (mild steel behaves differently from stainless)

Blank thickness in mm (the thicker, the more force)

Perimeter of the cut + draw in mm (this is what most beginners skip)

Whether the operation is blanking, drawing or bending (force multiplies differently)

The 60-second formula

For blanking and piercing, the force equation is:

Force (N) = Perimeter (mm) × Thickness (mm) × Shear Strength (MPa)

Shear strength in MPa = N/mm², so this product gives you Newtons directly — no division needed yet.

Convert Newtons to tonnes-force: T = Force (N) ÷ 9,807. The engineering shortcut is ÷ 10,000, which is accurate to within 2% for press selection.

Then apply a safety factor of 1.3 — never quote a press at the theoretical max. We use this on every RFQ. For complex shapes (louvers, deep draws) the perimeter estimate becomes the dangerous number, so we add a 0.2–0.5 mm radius rule and re-measure.

Worked example: 2.5 mm SPCC bracket

Cut perimeter: 480 mm. Thickness: 2.5 mm. SPCC shear strength: ~310 MPa.

Raw force = Perimeter × Thickness × Shear = 480 × 2.5 × 310 = 372,000 N = 372 kN.

Convert to tonnes of force: 372 kN ÷ 9.81 ≈ 38 tonnes-force. The common shortcut is ÷ 10 (gives 37 t), which is fine for first-pass sizing.

Apply the 1.3 safety factor: 38 × 1.3 ≈ 49 tonnes-force — a 63T press handles this with margin.

Where the math goes the other way: if the part is 6 mm thick or spans a 1,500 mm perimeter (large agricultural or HVAC panels), the same math lands at 250-320 T. Those jobs need the 250T or 500T press.

What happens when the tonnage is wrong

Too little force → part burrs, dies chip, the press stalls and trips the overload. You lose an afternoon on the floor, and possibly the tool.

Too much force → die components (especially punches under 3 mm) bend or shear. Tooling rebuild cost runs $1,000-$3,000 per cavity — and the lead time loss is worse than the money.

Right force with bad alignment → uneven shear, broken grain in deep-draw parts, springback surprises. This is the most expensive case because the part looks fine until your customer receives it.

When to skip the math and ask us

Stainless steel, high-strength steel (HSLA), or material thicker than 4 mm.

Deep draws deeper than 1.5× diameter, or step draws.

Parts with more than 2 mm of simultaneous trim + draw (compound dies).

Send your drawing and material spec. We will return the recommended press, the safety factor, and the tonnage we actually book for the job — usually within one business day.