What Is a CNC Punch Press?

Paul Scott

A CNC punch press is an automated production machine used to form or punch out pre-determined shapes from thin stock material. CNC stands for Computer Numerical Control and refers to the computer programs which control the machine's operational cycles. Most CNC punch presses are turret-type machines that consist of three basic assemblies: a powered press turret, a main work bed which moves two dimensionally, and a set of controls that include the computer station. The process of punching material involves a work piece, typically a thin metal sheet, being moved into position under the press die along an X- and Y-axis by the computer program. When the work piece is in position, the program instructs the die to move down and form or cut out the desired shape, and then back up to repeat the cycle.

A CNC operator must be able to program the punch press machine to perform the task needed and monitor the work, making all necessary adjustments.
A CNC operator must be able to program the punch press machine to perform the task needed and monitor the work, making all necessary adjustments.

Powered punch presses are large machines typically used in industrial settings to press form or cut out often intricate shapes from thin stock. The CNC punch press is one such machine that is controlled by a computer with very little operator input during the punching cycle. These machines are usually of a turret design that features a hydraulically-powered ram and die set housed in an enclosed turret. A movable table or bed is situated in front of and partially below the turret. This bed can move to feed work pieces along two axial planes, X and Y, or, in other words, backward and forwards, and side to side.

Both the bed and the die set of the CNC punch press are controlled by a central computer that translates a pre-loaded program into a set of sequential operations for both the die set and work bed. In this way, the machine will automatically advance the work piece through a pre-determined pattern of punch cycles. This automated operation is generally extremely precise and rapid, with typical punch cycles measured in milliseconds allowing for excellent production rates and high levels of accuracy. CNC punching is also economical, as the program can reduce the amount of wastage or scrap generation from any workpiece to a minimum.

The CNC punch press cycle consists of two basic parts — workpiece positioning and the actual punch cycle. The positioning places the workpiece exactly under the die set, and the punch cycle moves the die down to cut out or form the production part. Once the cut or punch is made, the die is moved back up, the work piece is re-positioned, and the cycle is repeated. When cutouts are punched, any scrap produced drops down into a collection bin for recycling. A CNC punch press not only allows for high production rates and outstanding accuracy, but can also generally punch more complex shapes than other press types.

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