Punch presses are used in stamping, punching, bending, shearing, converting, and assembly operations. They differ in terms of drive type and automation. Air-driven punch presses are powered by a pneumatic cylinder and are suitable for light-duty applications. Hydraulic presses are powered by a fluid-filled cylinder and can generate extremely strong forces to form metals and other materials. Manual presses are driven by hand, or powered with manual force that is magnified by a screw, lever or other mechanism. Mechanical punch presses are driven by a rotary motor and screw, toggle, or lever. By contrast, servo-controlled presses are driven directly by a servo motor. Some punch presses are controlled manually, through the use of operator interface devices such as footswitches, pendants, or push button controls. Others include a computer numeric controller (CNC) or programmable logic controller (PLC). Punch presses that are programmed and controlled with a personal computer (PC) interface allow users to set and adjust parameters such as speed and applied load. Indexing machines are fully automatic and can load parts and adjust parameters without operator intervention.
Important specifications for punch presses include operating force, rated capacity, production rate, and sheet capacity. Operating force is the maximum load required to cut or form parts during assembly. Rated capacity is the tons of pressure that the slide or ram exerts at the bottom of the stroke while working within the range of the press. With mechanical punch presses, operating force is a function of the bending capacity of the main shaft. For all types of punch presses, production rate is the number of operations performed or units produced per unit of time. Typically, this amount is expressed as the number of strokes, hits, cut-outs, cycles or hits per minute. For complex parts, the production rate depends on the total number of steps or operations required to fabricate a complete part. Most manufacturers specify sheet capacity in terms of maximum thickness, working length, and working depth. Working length is the maximum sheet length (largest dimension, X) or working distance from right to lift that can be punched, formed, or converted. Working depth is the maximum sheet (smallest dimension, Y) or working depth from front to back that can be punched, formed, or converted.
Punch presses are available with a variety of special features. Some machines include integral shearing capabilities or optional material feeders. Others include laser cutting or monitoring systems. Multi-station punch presses include rotary tools and turrets, progressive dies, transfer systems, or multi-tool die sits. Rotary punch presses index materials and allow operators to select an appropriate tool from the turret. Loading and stacking systems are complete manufacturing cells that often include material handling and degreasing subsystems. They provide sheet, part, and material handling.