CNC Turret Punching
Turret punching is done by placing sheet metal between a punch and a die mounted in accordance with each other in a press. Sometimes more than one punch is needed to produce the desired shape. After being punched the metal can then be sent to bending, forming, powder coating and welding operations.
The CNC turret punching process combines CAD computer technology with old school turret punching to produce intricate shapes and design in various types and thickness of sheet metal. CNC turret punching machines can be fitted with as many as 60 tools that can be switched to bring any one into position for punching. Square and round angular cuts (or punches) are used to create difficult designs.
Most machines have a table with rollers to allow the sheet metal to move easily. Where scratching needs to be kept to a minimal, like on polished metals or aluminum, brushes are used. Punches are not a flexible as other laser plasma cutting devices but they are markedly faster and more efficient for reproducing shapes and can take up to 600 strokes per min. Auto factories have numerous sizes and types of CNC turret punching available.
Car doors, parts of the frame, trunk and hood can all be cut from rough sheet metal using punching machines. Many machines have a safety button that coincides with the pressing down manually on a foot switch by an operator or machinist. This helps insure that all body parts are not between the die and sheet metal when thousands of pounds of pressure are applied. These machines can be as big as a room (as in the auto industry) and can operated robotically from a control room or computer. The CNC turret punching die comes in a male and female side. As these two sides are pressed together a holes forms in the spot on the metal where the direct pressure was applied, as if using a cookie cutter to produce shapes in dough.
Once the command is given form the computer the punching sequenced is initiated thus pushing the ram (form the top) to bottom through the plane of sheet metal. These ‘cycles’ are usually fast and last only a fraction of a second to allow for high volume work-loads. The resulting piece of metal punched form the sheet is referred to as ‘slug’ and drops through to a tray where it can be discarded and or recycled depending on the material. The computer integration of CNC turret punching is the main reason the machine can be cycled so fast.