Architectural Flashing Supply
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Shearing, slitting, notching and cutting · Lesson 4 of 4

Shearing, slitting, notching and cutting: defects, verification and case study

Reading bad edges, twist, bow and crook, slitting and notch defects and coating damage; the checks before a piece moves on; and a case worked through.

You will be able to: Diagnose sheared, slit, notched and field-cut defects from the evidence on the piece, choose the corrective action, and record the inspection for review.

9 min · 10 slides · 7 questions

All lessons in this module
Slide 1 of 10

Clearance shows in the edge

Too little clearance wears the blades faster and can leave a double, secondary shear band.

Too much clearance draws the metal between the blades, so the edge tapers and tears and the burr grows.

Blade clearance: correct, too tight, too looseThree magnified sheared edges. Correct: small rollover, clean burnished band and small burr. Too tight: a second burnished band below the first, from a double shear; both bands are traced and labelled. Too loose: a large rollover, a tapered, torn edge and a large burr.band 1band 2ABCcorrecttoo tighttoo loosesmall burrdouble bandtorn, big burr

Three magnified red edge sections. Correct: small rollover, clean burnished band, small burr. Too tight: two burnished bands, traced in teal and labelled band 1 and band 2, the double shear. Too loose: a large rollover, a tapered, torn edge and a large burr.

A
Correct clearance
B
Too tight: double, secondary shear band (band 1 and band 2)
C
Too loose: tapered, torn edge and large burr
Magnified sections, exaggerated. Too tight wears blades and double-shears; too loose tapers, tears and grows the burr.

Sources

Glossary

Twist
A sheared strip turning about its length, most likely on narrow strips.
Crook
A sheared piece curving in the plane of the sheet.
Bow
A sheared piece whose edges lift out of flat.
Camber
A slit strip curving sideways along its length, from clearance that differs edge to edge.
Edge wave
A wavy slit edge, caused by too much vertical knife overlap.