B for a slot or hole 1 diameter then the minimum distance d 2 5t r see fig.
Extruding holes sheet metal.
Extruded holes very close to the part edge can lead to sheet metal deformation or tearing.
A pre punched hole is required as a one hit pierce and extrude gives poor hole quality and has limited adjustment on the machine.
Unipunch tooling can be used to simultaneously punch a hole and extrude the material down.
C form height to thickness ratio to determine the minimum form height for sheet metal use the.
Center of extruded holes a 5 hole dia 2t extruded hole and bend edge c 3t r d 2.
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.
Extruding metal is one of the most extreme pressure applications in press working and generates lot of friction and heat.
Materials exhibiting good stretch capability and stretch distribution characteristics are best suited for extruding.
Extrusion is the process in which a continuous radial stretch flange is created by expanding a 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 minimum distance between two extruded holes is six times the material thickness.
Extruded hole to part edge b 3t d 2.
Relieve the punch after extruding the straight section to allow for lubricant to settle into the negative portion of the punch.
Both holes and regular extrusions are possible in sheet metal as well as thread features.
The following illustration shows the extruded hole geometry.
Therefore the minimum distance between the extruded hole to edge if maintained.
For a hole 1 in diameter the minimum distance d 2t r see fig.
Avoid large sheet metal parts with small bent flanges.
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.
Extrusions our commonly used to accept sheet metal screws or permit tapping into a deeper distance than just the material thickness.
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.
