Perforating Standards

Perforating Standards
The following standards are intended to aid designers, engineers, and buyers of perforated product in selecting the correct item for their application.

Sheet and Plate Size Specification
Standard stock size sheets and plates
(Typical: 36" x 96", 36" x 120", 48" x 96", 48" x 120")
The width and length will be standard mill shearing plus any stretch of the material by perforating, unless otherwise specified.

Sheets and plates resheared after perforating
Length and width tolerances for:
thickness lighter than 1/8" = ±1/32"
thickness 1/8" to 3/16" incl. = ±1/16"
thickness heavier than 3/16" to 1/2" incl. = ±1/8"
thickness heavier than 1/2" = check with our Sales Dept.
If special re-square tolerances are required, consult our Sales Department

Perforations (Open Area Calculator)
Round Perforations ­ Staggered (60 degree pattern) is standard. Variations include the 45 degree staggered, and Straight Line Pattern.
Square Perforations ­ Staggered Pattern or Straight Line Pattern.
Slotted Perforations ­ Side Staggered, End Staggered, or Straight Lines. Slotted Perforations will be round end slots; specify if square end slots are required.
Custom Perforations ­ Consult Ametco.

Spacing of Perforations (Open Area Calculator)
Spacing for large perforations will be designated by either Centers of Perforations, or by the Open area required. Spacing for small perforations will be designated by either Centers, or Open area, or if more practical, by the Number of Perforations to the Square Inch.

Pattern of Perforations (Perforated Patterns)
Unfinished End Pattern ­ As a result of tool design, some specifications of staggered pattern perforations yield a pattern that appears incomplete at both ends of the sheet. This is an industry standard.
Finished End Pattern ­ As a result of tool design, some specifications of staggered pattern perforations yield a completed pattern on both ends of the plate.
Staggered Perforations, both Round and Square ­ The pattern stagger is normally in the short dimension of the sheet. Holes in a straight row pattern are normally parallel to long dimension of sheet.
Slotted Perforations ­ Slots can be furnished parallel with either the length or width of the sheet in most cases.

Margins (Perforated Patterns)
Perforated stock size sheets and plates.
The long side of a sheet will be supplied with minimum margins. The short side of a sheet will have either minimum margins or no margins.
Sheets and plates resheared after perforating.
Special margins are available, but they must carry a tolerance within the limits of the perforating tool.
Unfinished end pattern is standard in the industry.

Flatness of Sheets and Plates
Perforated sheets or plates can, generally, be furnished to AISI flatness tolerances. However, if your job contains one of the following conditions you should consult Ametco's Sales Department.

Perforated sheet has extra wide margins.
Blank areas required within the perforated area.
Perforated sheet has a large percentage of open area.
Heavy gauge metal in relation to the size of the perforation.
Special alloys.
Stretcher leveled sheets.
Customer Supplied Materials
Material furnished by the customer must be referred to as "Perforating and Processing Only". All materials furnished must be of perforating quality. The weight of material furnished refers to the weight before perforating.


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