Tips for Safe, Successful Punching Mild Steel
Punches should wear out, they should not chip or crack. Several factors may contribute to punch chipping and cracking.
Here is a simple check list that will help minimize this failure.
1. Loose coupling nut.
This permits the punch to “move” during the punching process. Such movement will cause uneven pressures.
2. Misalignment. If the punch
is not aligned to the hole in the die, non-uniform clearance will result. The effect will be
uneven pressure on the face of the punch.
3. Improper clearance between punch and die.
The accepted standard clearance for punching mild steel that is less than 1/2" thick
is 1/32" total clearance. Punching material that is 1/2" or thicker requires a clearance of 1/16". Punching mild steel that is over 3/4"
thick may require even more die clearance.
4. Uneven stripping.
This occurs when the
stripper on the machine does not firmly and uniformly hold the plate down during the “up”
stroke. When this happens, the entire weight of the plate, plus the stripping strain, is concentrated on one side or edge of the punch.
Under extreme conditions, as much as 1/2" of the punch may break off.
Some of these conditions that we have described can be controlled on your shop floor. However, it is our job to furnish you with the strongest
punches possible. We do this by using the finest shock-resistant tool steels available, machine them to exacting tolerances, and then
harden and temper them under careful metallurgical procedures.
Punches usually crack and chip when punching high strength, high tensile plates over 1/2" thick. Our engineers have developed several super
tough punches which perform well under these difficult conditions.
Call 1.800.243.1492 or submit this simple form
to discuss your punch and die needs with our knowledgeable sales staff.