Extruding Holes Sheet Metal

Unipunch tooling can be used to simultaneously punch a hole and extrude the material down.

Extruding holes sheet metal.

Materials exhibiting good stretch capability and stretch distribution characteristics are best suited for extruding. C form height to thickness ratio to determine the minimum form height for sheet metal use the. Both holes and regular extrusions are possible in sheet metal as well as thread features. The minimum distance between two extruded holes is six times the material thickness.

Therefore the minimum distance between the extruded hole to edge if maintained. Applications include for self tapping sheet metal screws or in thicker material to permit tapping for machine screws. 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. Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch.

Extruded holes very close to the part edge can lead to sheet metal deformation or tearing. Can you clarify what you mean by extruded hole. The diameter of the pre punched hole ultimately determines the height of the extrusion. The extrusion punch should be made of highly wear resistant tool steel powdered metal pm preferably or solid carbide material.

The following illustration shows the extruded hole geometry. If an extruded hole is too close to the part edge it can lead to deformation or tearing of the metal. Of all of the factors controlling the success of an extruding operation material type and its mechanical properties are the most influential. Center of extruded holes a 5 hole dia 2t extruded hole and bend edge c 3t r d 2.

Extruded hole to part edge b 3t d 2. Extrusion is the process in which a continuous radial stretch flange is created by expanding a hole. Extruding metal is one of the most extreme pressure applications in press working and generates lot of friction and heat. For a hole 1 in diameter the minimum distance d 2t r see fig.

Extrusions our commonly used to accept sheet metal screws or permit tapping into a deeper distance than just the material thickness. 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. The punch should be polished linearly to a mirrorlike surface finish.