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Perforated Specifications

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Defining basic perforation patterns

Requirements which are not covered by or do not conform to the criteria below should always be specified by submitting a drawing of the full sheet, with unperforated margins clearly marked, together with details of the required perforated pattern and its orientation relative to the sheet.

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The basic perforation patterns most commonly used can be defined by determining the following criteria:


Length (of sheet/plate) = will always be taken to be the longer of the two dimensions

Width or height (of sheet/plate) = the shorter of the two dimensions

Pitch = measurement from the centreline of one hole to the centreline of the next hole

Bridge = measurement from the edge of one hole to the edge of the adjacent hole – ie the amount of solid material between holes

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Hole Shapes

Hole types are described according to shape and orientation;

R = Circular (Round)

C = Square

CD = Square, diagonals parallel to panel edges

H = Hexagonal

LR = Round-ended slots (‘Obrounds’)

LC = Square-ended slots

Hole Sizes

Hole sizes are specified in millimetres, width (w1) x length (w2), following the shape code for the hole.

Hole Pattern & Pitch

Following the code for hole shape and size, the pattern is specified using codes for arrangement (pattern) and spacing between hole centres (pitch)

For the T pattern (60º staggered pitch) and square U pattern (pitches equal in both directions), only the pitch p is stated.

For shapes R, C, CD, and H in the U or Z arrangements, both pitch p1 & p2 are stated as p1 x p2 with the shorter pitch p1 stated first.

If relevant to the requirement, the pattern should be defined further by specifying whether the straight row of holes should run parallel to the long side or short side of the panel.

Plain Margins should be specified along long and short sides of the panel, or each panel side if the margins or sides are not symmetrical about the centre lines of the panel.

Open Areas for Perforating Patterns

(NB letters used in figures below do not reflect ISO7806 / BS6511 designation)

EE Ingleton Engineering Sheffield

EE Ingleton Engineering is based within the heart of the Steel City, Sheffield in the extremely popular area of Kelham Island. Our wide breadth of equipment allows great control of our processes, and we offer our unrivalled service to customers both locally within Yorkshire and Nationwide.

Our ongoing success is based on a total dedication to customer service. We provide cost-effective, high-quality products with the very best speed, flexibility, and technical support to all our clients – from small firms to multi-national companies.