Perforated Design Details
The rule of thumb for perforating carbon steel and aluminum is that the hole
diameter should not be less thant the thickness of the material. The
closer this 1-to-1 relationship is approached, the higher the probability for
tool failure, and the greater the precautions necessary to avoid it. For
stainless steel and other higher strength materials, it is best to drop at least
one thickness gauge thinner than hole diameter. In some cases, variations
to these recommendations can be accommodated but with additional production
costs.
The material left between perforations is called bar width. The same
rule of thumb of the 1-to-1 relationship to thickness is the limit for bar width
as in hole diameter. Keep the bar width greater than the thickness of the
material to avoid problems. As the 1-to-1 relationship is approached, the
increasing number of punches required sharply escalates the process tonnage
needed to perforate the pattern, thus creating potential for problems. In
some cases, variations to these recommendations can be accommodated but with
additional production costs.
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If the sieving process requires a specified arrangement of holes, the
direction of flow must be clearly specified.
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H.P.S.I. = Holes per square inch
D = Diameter of hole or size of square hole
C = Centers (distance between centers) |
|
Round Hole
60° Staggered
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Round Hole
45° Staggered
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Square Hole
Staggered
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60° Staggered Round Hole Pattern
% Open Area = (90.69 (D)(D)) / (C x C)
H.P.S.I. = % Open Area / (78.54 (D)(D)) |
Straight Line Round Hole Pattern (not shown)
% Open Area = (78.54 (D)(D)) / (C x C)
H.P.S.I. = % Open Area / (78.54 (D)(D)) |
45° Staggered Round Hole Pattern
% Open Area = (78.54 (D)(D)) / (C x C)
H.P.S.I. = % Open Area / (78.54 (D)(D)) |
Square Hole Patterns - Straight and Staggered
% Open Area = (100 (D)(D)) / (C x C)
H.P.S.I. = % Open Area / (100 (D)(D)) |
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