Selecting a Punch or Press


Selecting a Punch or Press

The following information, while not totally applicable to all fabricating machinery included in this product area, is provided as a convenient general reference for metal punching operations up to and including large power presses. Specific questions not answered by this data may be directed to Roper Whitney without obligation.

Hole Size vs. Material Thickness

Punching holes in metal is the fast, economical way to get precise hole size, smoothness and minimum burr. Compressive strength of the punch steel determines that the thickness of the metal being punched must not exceed the diameter of the punch. This relationship varies with the type of material. For example: the minimum hole diameter will be 1/4" in 1/4" mild steel, 1/4" in 3/16" stainless steel, and 1/4" in 5/16" aluminum.

Maximum Rated Capacity

All punching tools have their maximum capacities for safe, dependable operation over a long life span. Tools listed on this site have a "rated capacity" based on their design strength. Before selecting a tool, use the charts (selectable in the left hand navigation bar) to determine the specific tonnage required to punch the size and shape holes through the type and gauge metal considered. These figures are for flat punch points. Shear on the punches (explained later) will reduce the tonnage required.