Hydraulic shears: guillotine and swing beam

A hydraulic shear, also called a plate shear, cuts sheet and plate in a straight line by driving an upper blade past a fixed lower blade. There is no heat and no kerf, so it suits shops that square sheet and cut strips and blanks in volume for press brakes, punches, rolls and welding.

How a shear cuts

The sheet is pushed against the backgauge or squared against a side arm, hydraulic hold-downs clamp it to the table, and the upper blade comes down at a slight angle to the lower blade, called the rake angle. Because of that angle only a short length of blade is cutting at any moment, so the force needed is far lower than cutting the full length at once. The metal is partly sheared and then fractures along the line between the two blade edges.

Two settings decide cut quality. The first is rake angle. A steeper angle lowers the force and lets a machine cut thicker material, as MC Machinery explains, while a flatter angle distorts thin strips less; Haco sets less angle for thin material for exactly that reason. The second is blade clearance, the gap between the blades, which should grow with thickness and hardness. Ursviken gives typical values of 5 to 8 percent of thickness for mild steel, 7 to 10 percent for stainless and 3 to 5 percent for aluminium. Too little gap causes friction and fast blade wear; too much leaves burrs and bent, rolled edges.

Guillotine or swing beam

On a guillotine shear the upper beam moves straight down in guides, and on most modern machines the rake angle is adjustable; Durma's VS series, for example, adjusts it from 0.5 to 2 degrees. On a swing beam shear the upper beam pivots at the rear and the blade travels in an arc. RAS, which builds swing beam machines, describes a fixed, low rake angle (0.9 degrees in its example), an upper blade that moves away from the lower one after the cut, quick clearance adjustment with an eccentric, and twist-free strips from about 10 to 15 times sheet thickness. Our swing beam versus guillotine comparison goes deeper.

The shears in our catalog show the spread of sizes:

Reading a capacity rating

Shear capacity is quoted for mild steel of a stated tensile strength, and often at the maximum rake angle. Haco rates the TSX series on 400 N/mm² mild steel, and MC Machinery states its GV capacities at the maximum cutting angle. Stronger material cuts thinner: MC's GV range is rated 16 to 25.5 mm in mild steel but 10 to 17 mm in stainless. Before buying, convert your hardest regular job (stainless, high-strength or abrasion-resistant plate) into an equivalent mild steel thickness and check the machine against that, not against the headline figure. Check which tensile strength each maker used, because the basis differs between brochures.

Other specs to compare

• Backgauge: reach (about 1 m on the 3 m machines in our catalog), speed, accuracy and CNC control. For long, thin strips, a rear sheet support stops the material sagging and spoiling the size.
• Strokes per minute at full and short cutting length, which set output on blanking work.
• Hold-downs: number, spacing and pressure control, so narrow strips and soft or coated sheet are held without marking. Haco offers hold-downs with soft feet inserts and pressure regulation.
• Blade gap and rake setting: manual, motorised or automatic from the control. On the Haco TSX the gap is set automatically from material thickness, starting at 0.05 mm for thin sheet.
• Blades: rectangular four-edge blades can be turned to a fresh edge three times before regrinding, and stainless-rated blades are available.
• Throat depth, if you need to slit sheet longer than the blade.

What your plant needs

A shear is one of the simpler machines to install: there is no assist gas, no fume extraction and no laser safety zone. It does need:

• Power for the hydraulic motor and pump unit, usually mounted at the rear. Confirm a 600 V three-phase build or plan a transformer; see 600 V power for imported machines.
• Space front and rear: room to handle full sheets in front, and space behind for cut parts to fall, with an optional scrap separator and conveyor such as Baykal offers.
• A level, solid floor and anchoring to the maker's drawing, covered in our floor preparation guide.
• Safeguarding. The blade and the hold-downs are cutting and crushing hazards. Haco lists a hand safety guard with hand gaps and safety light curtain guards. In British Columbia, WorkSafeBC guideline G12.29 covers power presses, brake presses and shears together; check the rules in your province.

Running costs

• Blades and regrinding. Rotate edges as they dull and regrind before damage spreads; correct clearance slows wear.
• Hydraulic oil and filters, changed on schedule, plus seals and hold-down pads.
• Electricity for the pump motor, modest next to thermal cutting processes that also consume gas.
• Material yield: a straight shear cut loses nothing to kerf, so rectangular blanks come out of the sheet efficiently.

Typical applications

Shears square and size sheet before bending, cut strips and blanks for HVAC and ductwork, produce rectangular blanks for the press brake, cut plate for trailer and farm equipment, and break full sheets down into sizes that fit smaller lasers and punches. Parts with holes or contours belong on a laser or plasma table; for straight cuts in volume, the shear remains a quick and simple tool.