| The
following approximate rule may be used for rapidly finding the pressure
in tons required for punching circular holes in sheet steel: Multiply the
diameter of the hole in inches by the thickness of the sheet steel and
multiply this product by 8o. The result is the pressure in tons
required.
To find the pressure required for punching holes in brass, multiply the diameter of the hole by the thickness, and multiply this product by 65. Example: - What pressure is required for punching a hole 2 inches in diameter through 1/4" steel stock? According to the rule: 2 X 1/4 X 8o = 40 tons. If a hole is not circular, use as a factor, instead of the diameter of the hole, one third of the total length of the outline of the hole to be punched. Example: - What pressure is required for punching a 1 inch square hole in 1/4" thick steel? According to the rule, the total length of the outline of the square is 4 inches. . One third of this is 1 1/3", and the pressure required is equal to: 1 1/3 x 1/4 x 8o = 26.6 tons. Example: - What pressure is required for punching a 1" by 2" rectangular hole in 1/4" thick brass? According to the rule, the total length of the outline of the rectangle is 6 inches. One-third of this is 2", and the pressure required is equal to: 2 X 1/4 X 65 = 32.5 tons. © Tom Martin 2001 |