Forging and forming

Roll forming: what goes wrong and where to inspect

Cold formed sections for racking, solar mounting, construction and vehicles are produced by passing strip through a series of roll stands that bend it gradually.

ISO2768 ISO1461

01How the process works

Coil is uncoiled, straightened and fed through 10 to 30 stands of shaped rolls, each bending the strip a little further. The profile is pierced in line or before forming and cut to length by a flying cutoff.

Typical problems are bow, camber, twist and end flare caused by residual stresses, as well as roll marks and dimensional drift as rolls wear. Profile drawings must define straightness and length tolerances clearly.

Uncoil and level. Strip straightened.
Pre-punching. Holes and notches punched.
Forming. Progressive bending through roll stands.
Cut-off. Flying shear to length.
Inspection. Section, straightness, length, holes.

02What typically goes wrong

Defect	Typical cause	How it is found
Bow and camber	Unbalanced forming, strip camber	Straightness measurement
Twist	Roll alignment	Surface plate check
End flare	Residual stress released at cut	Gauge at ends
Roll marks	Roll condition, lubrication	Visual
Coating damage	Pre-galvanised or painted strip	Visual, coating thickness
Hole position drift	Pre-punch timing	Gauges

03Where an inspector should look

Before production

Roll design and first profile approval
Strip grade, coating and thickness
Section gauge

During production

Section check per coil
Length and hole position
Strip lot traceability

After production

Straightness and twist
Coating condition
Bundling and marking

04Standards and references

ISO2768 ISO1461

EN 10162 (cold rolled steel sections), EN 10346 (coated strip), EN 1090 for structural use.

Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.

05How we support buyers of roll forming parts

Independent Quality ControlIncoming, in-process and final quality control performed independently at the supplier, with measured results and clear acceptance decisions. Pre-Shipment InspectionFinal random or complete inspection of finished goods before shipment: quantity, conformity, workmanship, packing and marking.