Shearing Metal Plates

Shears are equipped with two blades each, with the lower blade being fixed to the machine table. The upper knife, on the other hand, is movable and guided by a vertically guided link. The knives are arranged in such a way that a cutting gap is created between the blades.

The correct cutting clearance

The width of this gap should always be selected as small as possible. If the upper and lower cutters are too far apart, less force is needed for shearing metal sheet/plate, but when the upper cutter is lowered material deformation occurs at the edges. These then have to be straightened and deburred in a further step. If the cutting clearance chosen is too small, shears have to apply far more force to cut through materials.

This results in a greater load on the machine and cutters. In order not to overload our machines and nonetheless achieve very good cutting quality, the optimum cutting clearance has to be chosen depending on the material and sheet or plate thickness.

With our CNC-controlled machines, only the material and sheet thickness have to be chosen. The upper cutter is positioned at an optimum distance from the bottom cutter. Before shearing the material is placed on the machine table and moved into the correct position. CNC-controlled stops (gauges) help to quickly align the sheets on the shearing table. With older shears a wire illuminated from above is used; it throws a shadow on the metal sheet panel, when the workpiece is inserted.

What problems can occur during cutting?

If very long and narrow sheet metal strips are required, the shear forces that act on the metal can cause deformations. Only the material behind the upper cutter is affected by this effect, as the part in front of the cutter is fixed by the hold-down.

As there is no hold-down attached behind the cutter, twisting or torsion can occur, with which the cut sheet metal strips are highly deformed. A small cutting clearance is decisive to cut narrow sheet metal parts without twisting.