Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch.
Extruded hole in sheet metal.
The minimum distance between two extruded holes is six times the material thickness.
A pre punched hole is required as a one hit pierce and extrude gives poor hole quality and has limited adjustment on the machine.
If extruded holes are too close it can lead to metal deformation.
B for a slot or hole 1 diameter then the minimum distance d 2 5t r see fig.
The minimum distance from an extruded hole to an edge is three times the material thickness.
Therefore the minimum distance between the extruded hole to edge if maintained.
A legacy product extrude tite screws have been now largely superceded by fastite 2000 fasteners.
Extrude tite screws were designed to resolve the fastening problems of stripping and spin out in thin sheet metal found when using standard round bodied sheet metal screws.
The minimum distance from an extruded hole to a bend is three times the material thickness plus the bend radius.
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.
Extruded hole to part edge b 3t d 2.
C form height to thickness ratio to determine the minimum form height for sheet metal use the.
The diameter of the pre punched hole ultimately determines the height of the extrusion.
Alternately the hole could be pre pierced in a separate station and then the edges extruded at a second station.
Extruded holes very close to the part edge can lead to sheet metal deformation or tearing.
Certain distance should be maintained between two extruded holes in sheet metal designs.
For a hole 1 in diameter the minimum distance d 2t r see fig.
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.
The following illustration shows the extruded hole geometry.
Applications include for self tapping sheet metal screws or in thicker material to permit tapping for machine screws.
The extrusion punch should be made of highly wear resistant tool steel powdered metal pm preferably or solid carbide material.
Extrusions our commonly used to accept sheet metal screws or permit tapping into a deeper distance than just the material thickness.
Increased torque performance in thin sheet metal applications.
The punch should be polished linearly to a mirrorlike surface finish.
It is recommended that the minimum distance between two extruded holes should be six times the thickness of sheet metal.
