Punching is a sheet-cutting process that works by shearing: a punch comes down, passes through the sheet resting on a die and detaches a hole or shape in a single stroke, the slug being cleared away. The clearance between punch and die, a fraction of the sheet thickness, determines the quality of the cut.
CNC punch presses carry a turret holding many tools: round, square, oblong and special shapes. The sheet is moved under the striking head, at several hundred strokes a minute for simple holes. To obtain a contour larger than the tool, it is “nibbled” by striking several times with a slight overlap. The same machines can also form the sheet: louvres, embossings, extruded collars that can be tapped, markings. For very high volumes, progressive tools on a press perform several operations per stroke. Punch presses handle thicknesses of a few millimetres.
Punching suits light sheet metal parts with many holes and repeated shapes: ventilation grilles, mounting plates, electrical cabinet panels, perforated brackets. On simple patterns it is often faster than laser cutting, which remains more flexible for complex contours, one-off shapes and thick sections. Some machines combine punch and laser. It falls within the sheet metal and cutting capability, and is followed by bending. The guide to the price of laser cutting and sheet metalwork compares the cutting processes.
In a quote request. Supply the flat pattern as a DXF, the material, the thickness and the quantity. Flag unusual shapes: a special tool may be needed, or the workshop will cut those areas by laser. Punching leaves a burr on the die side and can distort thin, heavily perforated sheet: state your flatness and deburring requirements.