Power Press Tonnage Calculator
Work out the tonnage required for punching, blanking or bending a job — then see which Basant power press (20 to 1000 ton) is rated to run it.
How Press Tonnage Is Calculated
Tonnage is the force a power press must deliver to punch, blank, or bend a given material without straining the frame, die, or motor. Selecting a press below the required tonnage risks incomplete cuts, die damage, and frame stress; selecting one far above it wastes power and increases per-part cost. Basant Mechanical Works has been sizing presses for Indian sheet metal, automotive, and hardware manufacturers since 1957 — the calculator above uses the same working formulas our engineers use during machine selection.
Perimeter is the total length of the cut edge in millimetres (for a circle: π × diameter; for a rectangle: 2 × (length + width)). Shear strength depends on material — mild steel typically runs 30–40 kg/mm², stainless steel around 55 kg/mm², aluminium as low as 18 kg/mm².
For bending operations, tonnage depends on the die opening (V-width) rather than perimeter — a narrower die requires proportionally more force for the same bend length and thickness.
Always add a safety margin. Material thickness tolerance, die wear over thousands of strokes, and the press not delivering 100% rated force through the full stroke all reduce effective capacity over time. A 20–30% margin above the calculated figure is standard practice — round up to the next available press size rather than down.
Basant Power Press Range by Tonnage
| Tonnage range | Typical use | Recommended series |
|---|---|---|
| 20 – 50 ton | Light punching, small brackets, electrical components | C Type Power Press |
| 50 – 150 ton | General stamping, automotive brackets, washers | H Frame Power Press |
| 150 – 300 ton | Deep drawing, heavier stamping, forming | Pneumatic Power Press |
| 300 – 1000 ton | Forging, hot stamping, billet shearing | Forging Press |
FAQ
How do I calculate press tonnage for punching?
Multiply the cut perimeter (mm) by material thickness (mm) by the material's shear strength (kg/mm²), then divide by 1000. Add a 25–30% safety margin and round up to the next standard press size.
What tonnage press do I need to punch a 50mm hole in 2mm mild steel?
Perimeter = π × 50mm = 157mm. 157 × 2 × 40 kg/mm² ÷ 1000 = 12.6 tons raw. With a 25% safety margin that's 15.7 tons — a 20 ton press handles this comfortably, with headroom for multi-hole dies.
Is tonnage the same for cutting and bending?
No. Bending typically needs less force than cutting the same length and thickness of material — unless the die bottoms or coins the bend, which can multiply the required force 3–5 times.
What happens if I use a press with too little tonnage?
The press stalls near bottom dead centre, the clutch slips and overheats, and repeated overloading can crack the frame or damage the crankshaft — failures that are rarely economical to repair.
Is this calculator accurate enough for final press selection?
It gives a reliable working estimate using standard shear-strength formulas. For critical or high-volume jobs, share your part drawing with our engineering team for a verified tonnage and die-cushion recommendation, free of charge.