Hole and Bar
Perforated holes and the space between them (referred to as “bars”) are produced by precisely machined punches penetrating a given material. While not visible to the naked eye, the top and bottom of perforated holes are not exactly the same. Dependent on the material type and thickness and the size of the punch, the force required to perforate material causes the punches to shear approximately the first 1/3 of it. As the punches continue to move downward through the material, the buildup of pressure causes the remaining 2/3 to eventually give way - resulting in a breakout, which is slightly larger and uneven.
Dimple Holes
With the employment of special tooling and production techniques, holes can be indented slightly below the surface of the material. Providing a top side that is extremely smooth and a bottom side
that is very rough, dimple holes are ideal for those applications where a typical hole may not be desired.
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Generally an option only for round
staggered and straight patterns, dimple holes are identified as such within the round hole portion of the perf pattern section. Because we are constantly developing new tooling and production techniques, if dimple holes are desired in a pattern where it is not shown as being an option, contact our Customer Service Department and one of our representatives will check on our ability to produce what you want. Because dimple holes may vary in depth and slope depending on the material type and thickness and the size of the hole, required tolerances should be discussed with a Sales Engineer.
The table below shows the hole and bar tolerances for rounds and squares. They meet ASTM standard E 323, Specification for Perforated Plate Sieves for Testing Purposes. |
