Sourcing a bespoke open profile is different from buying a catalogue product. Start with the right information and the process is fast and predictable; start with gaps and you lose weeks. This guide covers what to prepare before approaching a roll forming manufacturer, and how the project actually runs.
1. What your drawing must contain
The critical document is the cross-section drawing, ideally as DXF or PDF. It should show all internal and external dimensions, material thickness, bend radii, and a clear indication of which dimensions are tolerance-critical. Do not put tight tolerances on everything — calling out only what genuinely matters lowers cost and simplifies production.
Also specify: profile length (and length tolerance), estimated annual footage, hole or slot patterns with positions, and where the profile will be installed. That last point matters more than buyers expect — knowing the application lets the manufacturer suggest a more economical section.
2. Choosing material and coating
In roll forming the material is fed as coil and is already coated before shaping. This removes the need for a post-galvanizing bath and gives uniform coverage across the whole surface.
Common choices: **black (uncoated) steel** for indoor or to-be-painted applications; **hot-dip galvanized (DX51D+Z, S350GD)** for general outdoor use; **Zn-Al-Mg (ZM / Magnelis)** for harsh environments such as coastal, agricultural and high-humidity sites, where it provides self-healing protection at cut edges; and **stainless** for chemical and food-contact applications.
Strength grade also drives the section: with a higher-yield material such as S350GD you can reach the same load capacity at a thinner gauge, lowering cost per unit of strength.
3. How the process runs
**Technical review.** Your drawing is assessed for roll-formability, the number of stations required, and possible improvements. Small geometry changes at this stage often produce significant cost reductions.
**Tooling and roll design.** A dedicated roll set is designed and machined for your section. At a plant that builds tooling in-house, this step is markedly shorter.
**First article.** The line is set up, first parts are produced and measured. Series production does not begin until you sign off.
**Series production.** Repeatable runs on approved tooling, with holes and cut-outs applied in-line, profiles cut to length and packed for shipment.
4. Realistic tolerance expectations
Roll forming is exceptionally strong on repeatability: thousands of metres through the same tooling come out effectively identical. The process is nonetheless affected by springback and by variation between material batches. So rather than putting tight tolerances on everything, identify what is functionally critical.
If hole positions are assembly-critical and punched in-line, discuss cumulative tolerance over long runs with your manufacturer. On long profiles, accumulated tolerance across the full length matters as much as hole-to-hole spacing.
Ready to start?
Send us your section drawing (DXF or PDF), your estimated footage and your material preference. Our technical team will come back with a manufacturability assessment — and, where useful, suggestions on the section that reduce cost.