Extruding Holes Sheet Metal

Of all of the factors controlling the success of an extruding operation material type and its mechanical properties are the most influential.

Extruding holes sheet metal. Avoid large sheet metal parts with small bent flanges. Therefore the minimum distance between the extruded hole to edge if maintained. Both holes and regular extrusions are possible in sheet metal as well as thread features. 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. 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. If an extruded hole is too close to the part edge it can lead to deformation or tearing of the metal. Extruded hole to part edge b 3t d 2.

A pre punched hole is required as a one hit pierce and extrude gives poor hole quality and has limited adjustment on the machine. 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. The following illustration shows the extruded hole geometry. The diameter of the pre punched hole ultimately determines the height of the extrusion.

Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch. Extrusions our commonly used to accept sheet metal screws or permit tapping into a deeper distance than just the material thickness. Unipunch tooling can be used to simultaneously punch a hole and extrude the material down. For a hole 1 in diameter the minimum distance d 2t r see fig.

The punch should be polished linearly to a mirrorlike surface finish. Extruded holes very close to the part edge can lead to sheet metal deformation or tearing. 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. B for a slot or hole 1 diameter then the minimum distance d 2 5t r see fig.

Can you clarify what you mean by extruded hole. The minimum distance between two extruded holes is six times the material thickness. Applications include for self tapping sheet metal screws or in thicker material to permit tapping for machine screws. Extruding metal is one of the most extreme pressure applications in press working and generates lot of friction and heat.