Extruding Holes Sheet Metal

Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch.

Extruding holes sheet metal.

For a hole 1 in diameter the minimum distance d 2t r see fig. A pre punched hole is required as a one hit pierce and extrude gives poor hole quality and has limited adjustment on the machine. Die buttons with oversized internal diameters typically with a 020 radius instead of a cutting edge are used to permit the material to flow downward and punch an extruded hole. In low carbon steel sheet metal the minimum radius of a bend should be one half the material thickness or 0 80 mm 0 03 inch whichever is larger.

Avoid large sheet metal parts with small bent flanges. Applications include for self tapping sheet metal screws or in thicker material to permit tapping for machine screws. Center of extruded holes a 5 hole dia 2t extruded hole and bend edge c 3t r d 2. Both holes and regular extrusions are possible in sheet metal as well as thread features.

Extruded holes very close to the part edge can lead to sheet metal deformation or tearing. Extruded hole to part edge b 3t d 2. Therefore the minimum distance between the extruded hole to edge if maintained. Materials exhibiting good stretch capability and stretch distribution characteristics are best suited for extruding.

The diameter of the pre punched hole ultimately determines the height of the extrusion. Extrusion is the process in which a continuous radial stretch flange is created by expanding a hole. C form height to thickness ratio to determine the minimum form height for sheet metal use the. Can you clarify what you mean by extruded hole.

Extruding metal is one of the most extreme pressure applications in press working and generates lot of friction and heat. Tap fix screws for extruded holes in light gauge steel this article provides tap fix hole size recommendations for metals using light gauge punched extruded materials. The following illustration shows the extruded hole geometry. Unipunch tooling can be used to simultaneously punch a hole and extrude the material down.

If an extruded hole is too close to the part edge it can lead to deformation or tearing of the metal. The punch should be polished linearly to a mirrorlike surface finish. Of all of the factors controlling the success of an extruding operation material type and its mechanical properties are the most influential. B for a slot or hole 1 diameter then the minimum distance d 2 5t r see fig.