Shear cutting force calculator
Shear capacity is quoted in tons, but the force depends on the cut: how thick, how long, and what alloy. Enter those and this gives you the planning figure — plus the margin a machine rating should carry.
Planning figure only, from the progressive-cutting relationF ≈ 0.1 × shear strength × thickness × cut length with the rake angle applied. Real force moves with blade clearance, blade condition, material temper and how square the cut is. Confirm against your machine maker's chart before committing to a machine — and remember the machine rating, not just the force, has to carry the cut.
What drives the cutting force
Thickness first. Unlike a press brake, where force rises with the square of thickness, shear force rises roughly linearly — but it starts from a much larger base, because the blade is severing the full section rather than forming it. Doubling the plate roughly doubles the force.
Cut length next. Force scales with the length of the cut line — a longer cut loads the machine structure more as well as the blades, which is why machine ratings rise with cutting length even when the thickness stays the same. A shear rated for your thickness at a short length is not automatically rated for the same thickness at full length.
Alloy and rake angle. Stainless needs about 1.5× the mild-steel force and aluminium about half, at the same thickness. The blade rake angle works the other way: a smaller rake needs more force but twists the sheet less; a larger rake cuts easier and distorts more. The 1.5°-3° range is the usual compromise.
Blade clearance is the quiet variable
Force estimates assume correct blade clearance — typically a percentage of material thickness, set by the machine maker. Too wide and the material tears and rolls instead of cutting cleanly; too narrow and the force climbs while the cut quality still suffers. If your shear needs more force than it used to for the same cut, check the blades and the clearance before blaming the machine's rating.
Sizing the shear against the brake
The shear feeds the brake, so size it against your blanking workload: the widest plate you cut at the thickest gauge you cut. The guillotine shear and swing beam shear pages cover the two machine classes, and the size guide covers matching the shear to the brake and the bed length.
Send these numbers to us
Thickness, cutting length and the material. We will come back with a shear configuration and a quote — sized to your worst cut, not your average one.