Extruded Hole In Sheet Metal

Extrusions our commonly used to accept sheet metal screws or permit tapping into a deeper distance than just the material thickness.

Extruded hole in sheet metal.

An extruded hole is one that is generated at one station using a specially stepped punch that first shears a smaller hole and then follows through to deform the local area around the hole into a projection by limited forward extrusion. The minimum distance from an extruded hole to an edge is three times the material thickness. B for a slot or hole 1 diameter then the minimum distance d 2 5t r see fig. Extruded hole to part edge b 3t d 2.

If extruded holes are too close it can lead to metal deformation. Center of extruded holes a 5 hole dia 2t extruded hole and bend edge c 3t r d 2. For a hole 1 in diameter the minimum distance d 2t r see fig. Applications include for self tapping sheet metal screws or in thicker material to permit tapping for machine screws.

The following illustration shows the extruded hole geometry. 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. C form height to thickness ratio to determine the minimum form height for sheet metal use the. Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch.

A pre punched hole is required as a one hit pierce and extrude gives poor hole quality and has limited adjustment on the machine. Certain distance should be maintained between two extruded holes in sheet metal designs. The minimum distance from an extruded hole to a bend is three times the material thickness plus the bend radius. The extrusion punch should be made of highly wear resistant tool steel powdered metal pm preferably or solid carbide material.

The diameter of the pre punched hole ultimately determines the height of the extrusion. It is recommended that the minimum distance between two extruded holes should be six times the thickness of sheet metal. Therefore the minimum distance between the extruded hole to edge if maintained. Extruded holes very close to the part edge can lead to sheet metal deformation or tearing.

Increased torque performance in thin sheet metal applications. The punch should be polished linearly to a mirrorlike surface finish. A legacy product extrude tite screws have been now largely superceded by fastite 2000 fasteners. Unipunch tooling can be used to simultaneously punch a hole and extrude the material down.

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.