Diamond Manufacturing Company
Perforated and Value Added Metal Specialists

How to Specify Your Perforated Job

The following insights are offered on each of the factors that affect the quality, cost and delivery of a perforated product. Please consider these factors when designing or specifying perforated material:

Material Type

While it’s important to use a material that is appropriate for the application, choosing one that is typically used for perforation is likely to be more available. If you prefer material from a specific origin (i.e., domestic, NAFTA, etc.) or require other certifications, please indicate your request in advance. Failure to do so may result in us having to revise the quote.

Material Format

Perforated materials are commonly produced in a number of standard formats, but may also include custom configurations. At the outset of your perforating job, please indicate if you require standard sheets, cut-to-size blanks, standard coils or slit-to-width coils.

Material Thickness

While materials of various thickness can be perforated, full width perforating presses are designed to handle materials that range between .004" to .25" thick. Going outside of these tolerances will limit the types of patterns that may be applied and even affect the end product.

Hole Size

While a wide range of hole sizes can be perforated, the ability to produce them is dependent on the thickness of the material. As a rule of thumb, a greater than 1 to 1 ratio should be maintained (i.e., 1/8" holes in 1/16" thick material). In the event that the hole size is close to, equal to, or less than the thickness of the material, the greater the likelihood that the punches may break — resulting in either imperfect or missing holes in the material. For this reason, where applications require the 1 to 1 ratio to be either pushed or exceeded, it is best to discuss with a Customer Service Representative the level of allowance for imperfect or missing holes and the cost associated with meeting that level.

Hole Shape and Configuration

While it is important to use a hole shape (i.e., round, square, slot, etc.) and configuration (i.e., staggered or straight) that provides the best solution for the application, choosing one that can be produced with existing tooling minimizes costs and enables faster delivery.

Open Area

Patterns that contain extreme proportions of open areas (i.e., 60% and higher) can increase material distortion and adversely affect the quality of the end product. It can also increase the costs required to minimize the distortion. This is especially true when the perforated area is surrounded with margins on all four sides.


While they can be made in practically any size and can omit the need for having to weld perforated material to non-perforated material, margins can increase the difficulty in getting material within a desired flatness tolerance and can cause camber. This is especially true when:

  • margins are wide (i.e., 3" or more)
  • margins are unequal
  • margins are on all four sides
  • the material type is hard (i.e., Stainless Steel 300 series: 1/2, 3/4, and full hard aluminum)
  • material is thick (i.e., 11 ga or more)
  • the perf pattern is of a high open area (i.e., 40% and higher)

To minimize the amount of work and the associated cost required to get the material flat and without camber, you need to either reduce or change one or more of these attributing factors. If unable to do so, less stringent tolerances may be required.

End Margin Pattern

Unfinished and Finished

Industry standards call for the production of perforated areas with unfinished ends, but finished ends are possible as long as the particular tool being used is capable of doing so. In most cases, producing finished ends requires special production techniques. For this reason, finished ends may cost more. To find out if a desired pattern can be produced with finished ends, contact one of our Customer Service Representatives. Unless otherwise specified, unfinished ends are quoted and produced.

Blank areas and Locator holes

Blank areas and locator holes can be made in any pattern (i.e., center spacing), however the ability to do so depends on the versatility of the tool being used. To find out whether or not the blank areas or locator holes can be produced with the existing tool without modification, submit a drawing in advance.


We will strive to meet all desired tolerances, however please keep in mind that the ability to do so depends on the material and any thresholds in costs that may have been implemented by the customer. Two tolerance grades, Diamond Standard and Diamond Superior, are available. Unless requested, Diamond Standard tolerances are held. To ensure that critical tolerances are held, specify Diamond Superior.

Surface Finish

While measures are taken to keep surface blemishes to a minimum, imperfections resulting from perforating, roller leveling, and shearing do occur and are therefore considered standard and acceptable. If material surface finish is critical, then it should be indicated on the request for a quote so that additional measures can be put in place (i.e., the use of vinyl coated material, paper interleaving, etc.).

Degrease, Fabricate, and Finish

While perforated product can be supplied degreased, fabricated or finished, unless requested, these secondary procedures are neither quoted nor performed. Although they may prolong delivery, secondary operations add value to your perforated product. Allow Diamond to administer these applications. We'll make it easy for you and save you the cost of doing it on your own.

Packaging & Labeling

While material can be packaged and labeled to customer specifications, anything more elaborate than the Diamond standard may increase costs. To calculate the number of skids required to complete the shipment, and to ensure that the product can be unloaded at the time of delivery, the maximum skid weight and unloading capabilities should be communicated to the Customer Service Representative at the time of quoting. Failure to due so may affect the packaging cost and possibly result in problems when unloading material.

Over- and Under-runs

While it is Diamond’s intent to accurately fulfill quantity requirements, piece counts may either be over or under the ordered amount due to product spoilage or unplanned recovery of parts. If over, it is customary to ship good product and charge for it. If under, it is customary to ship short and bill accordingly. Typically the over- or under-runs involve only a few pieces. Therefore, unless the exact quantity is specified on the quote, over and under shipments are considered acceptable and the order complete once shipped.

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