Galling is an adhesion to the punch tip by the metal being punched, caused by pressure and heat.
The best technique for removing galling is to rub it off with a fine stone. The rubbing should be done parallel to the direction of the punching motion. This will polish the surface that contacts the material, decreasing any chance of future galling. Do not sandblast, belt sand or use other harsh abrasive methods. These create a coarse surface finish to which material adheres more easily. Punches made of high speed steel can be Maxima™ coated to help prevent galling when highly abrasive materials are punched.


Shake-and-break is a popular name for this easy method of separating multiple parts from a sheet of material.
The method is based on small, interconnecting tabs between the parts created by programming spacing of the shearing or slitting punch. These tabs keep the sheet and parts intact while being punched, yet are easy to separate off the machine. The tabs should be .008”(0.2mm) wide. Straight, curved, or corner shaped tools are available.


Combating material warp
If you are punching a large number of holes in a sheet and the sheet does not stay flat, it could be caused by the cumulative effect of punching. Each time a hole is punched, material surrounding the hole is stretched downward, placing the top of the sheet in tension. The downward movement causes a corresponding compression at the bottom of the sheet. One way to counteract this effect is to punch every other hole first and then come back and punch the remaining holes. This places the same amount of force on the sheet, but it disrupts tension/compression accumulation that occurs when punching operations follow one another in close succession and in the same direction. Excessive material warpage can also occur when there are many closely spaced forms on a sheet. One solution, if cosmetically acceptable, is to incorporate a “gripline” into the forming assembly. Griplines are basically a “V” shaped groove that is embossed into the sheet around the perimeter of each form. The effect is to cut the stress away from the surface of the sheet and contain it in the area where the form is made.


Use Mate’s urethane stripper pads to punch painted surfaces without marring.
These self-stick pads can be applied to ULTRA TEC™ stripper faces. Pads are available for all stations A through E.


If stainless steel extrusions are distorted, apply a good forming lubricant to the material before making the extrusion.
Not only will the material release from the die better, it slides over the die surface smoothly when being formed. This gives the material a better opportunity to distribute the forces of bending and stretching, preventing distortion in the formed wall and tearing at the base of the extrusion.

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