What pre-treatment is needed for raw steel before roll forming?

Standard pre-treatment of raw steel strips is essential to guarantee stable roll forming quality and reduce machine wear, mainly including surface cleaning, shape straightening, inspection and edge trimming as core steps.

First of all, incoming material inspection is the first procedure. Operators check coil thickness, yield strength, surface coating and dimension to reject severely out-of-spec raw materials. Steel with inconsistent hardness or excessive thickness fluctuation is sorted out in advance to avoid finished profile size deviation.

Secondly, surface cleaning removes contaminants on steel surface. Rust, oxide scale, greasy dirt and welding residues are cleared by wire brush, shot blasting or chemical degreasing. Foreign attachments would scratch forming rollers and profile coating during molding, even block punching dies for pre-punch lines like cable tray and solar bracket equipment. Galvanized coil with floating zinc dross also needs surface brushing.

Thirdly, strip leveling via pre-leveler is the most critical pre-processing. Most steel coils have inherent camber, edge wave and internal residual stress after coiling. Multi-roller flattening equipment eliminates bending deformation and makes strip flat before entering forming stations, effectively preventing strip wandering, profile torsion and uneven cold bending stress.

For narrow-width or irregular edge coils, edge trimming is optional pre-treatment to cut burrs and uneven side edges, ensuring stable feeding into guide rollers. In addition, moisture-proof drying is required for damp raw steel to avoid later rust inside finished profiles.

Complete pre-treatment greatly lowers scratch, twisting and dimensional error defects and extends forming roller service life obviously.

1. GB/T 7714-2015

[1] Jiang R. Preprocessing Technology of Raw Strip for Cold Roll Forming Production[J]. Metal Processing Technology,2025,41(04):58-65.

2. APA 7th

Jiang, R. (2025). Preprocessing technology of raw strip for cold roll forming production. Metal Processing Technology, 41(4), 58–65. 

3. MLA 9th

Jiang, Rong. "Preprocessing Technology of Raw Strip for Cold Roll Forming Production." Metal Processing Technology, vol.41, no.4, 2025, pp.58-65