A turret punch press is a tool used for industrial sheet metal fabrication. Capable of the basic operation of punching holes, modern punch presses are also able to cut elaborate shapes and create limited three-dimensional forms in sheet metal. Most turret punch presses are large machines controlled by computers, although smaller, manual versions do exist.
As the name suggests, the main components of a turret punch press are the turret and the punch. The turret sits in a C-frame or arch above the work area. It contains the punches and other tools that are used to shape the sheet metal. Individual punches vary in size and shape based on the desired fabrication result. When in use, the punches slide up and down a guiding mechanism
During basic operation, the turret, or sometimes a component of the turret, moves to bring the appropriate punch forward. The punch is rammed toward the work area, where it comes into contact with the sheet metal. After the punch forces through the sheet metal, it slides into the corresponding die below the table. It is the punch-die set that controls the shape of the hole or deformation.
Sheet metal is held in place within the turret punch press by a set of clamps. Brushes and rollers move the clamped sheet metal below the working turret in between each punch. Most turret punch presses are self-stripping and are capable of removing the punched pieces of sheet metal as the work progresses.
Most turret punch presses are computer numerically controlled (CNC). After a design for the finished sheet metal project has been loaded into the computer, the punch press functions automatically. CNC control allows for increasingly complex designs, increased efficiency, increased accuracy and greater flexibility with regard to changes in the design.
Newer turret punch presses are hydraulically controlled. Hydraulics in combination with CNC control provide the most flexibility in sheet metal design. Older machines, however, were mechanically controlled. The first turret punch presses were driven by flywheels turned by steam.
When comparing turret punch presses on the market, there are a number of commonly reported specifications that are useful. For example, the force rating, usually described in tons, is a measure of how much force the punch can bring to bear on the sheet metal. A commercial turret punch press will most commonly have a force rating of 30 tons.
Punch rate and punch accuracy are also commonly reported specifications when comparing punch machines. The maximum area and thickness of sheet metal that can be handled by the machine is important for a user to know. Clamp systems for holding the metal in place usually are described because they are essential for smooth movement of the metal and minimizing unworkable edges.
Descriptions of the turret are also useful when comparing punch presses, specifically the turret arch type and the number of stations for tools. The included and available punches and tools usually are also listed for each press and will give perhaps the best idea of what the machine is capable of doing. If the machine is a CNC machine, the description also will include the software and the software’s capabilities.