Ask two mills to quote the same trapezoidal section and the prices can come back 30% apart. Usually it is not labour and it is not material. It is how they form the wire. Some shops only roll. Some only draw. We do both, in the same building, and that is the main reason we can hold ±0.02 mm on shapes other people quote as "to drawing, best effort".
What Rolling Is Good At
Cold rolling squeezes the wire between shaped rolls. Two things it does well: it puts the section in, and it does it fast. Round wire becomes a trapezoid or a D-shape in a handful of passes without being pulled through a die, so the metal takes less work and the surface comes out clean.
What rolling is not good at is fine tolerance. Roll wear shows up straight in the section, edges come out slightly rounder than the drawing wanted, and holding ±0.02 mm on every dimension through a long run is not realistic. Anyone promising that from rolling alone is measuring at the good end of the coil.
What Drawing Is Good At
Cold drawing pulls the wire through a die. That is where tolerance and surface come from. The die sizes the section, straightens the wire on the way through, and leaves a finish that both polishing and plating like. Drawing is also how temper is set: more final reduction, harder wire.
Its limit is shape. Pulling a complicated section out of round wire takes many passes, and every pass needs its own die. For a profile with a rib or a deep groove, drawing alone is slow and expensive, and each extra pass is another chance to mark the surface.
The Route We Actually Run
The order of operations is not a marketing line, it is the production route:
- Cold roll the section close to final shape. Fast, and it forms the profile without fighting a die.
- Bright anneal before the next reduction, to take the hardness back out.
- Cold draw to final size, holding the control dimension to ±0.02 mm.
- Final reduction to the temper you ordered: soft, half-hard or hard.
The anneal between passes is a bright anneal in a protective atmosphere, so there is no oxide scale to pickle off afterwards. That matters more than it sounds. Pickling is where a lot of mills quietly lose the edge quality they had before annealing, and you find out after polishing.
What It Means for Your Part
| Rolling only | Drawing only | Roll then draw | |
|---|---|---|---|
| Tolerance | Loose, drifts with roll wear | Tight on simple shapes | ±0.02 mm on the control dimension |
| Section | Simple flats and squares | Round, square, simple profiles | Ribs, grooves, asymmetric sections |
| Surface | Good, edges less crisp | Bright, straight | Bright, crisp edges, no pickle marks |
| Lead time | Shortest | Longer on complex shapes | 20 working days on standard sections |
| Cost | Lowest | Middle | Higher than rolling, still cheaper than many-pass drawing |
Where You Feel the Difference in the Finished Part
On a wedge screen, edge crispness decides how the slot measures. A slightly rounded edge from rolling alone reads as a bigger slot at inspection and behaves like one in service. On a zipper element, thickness consistency decides whether the parts interlock or jam, and drawing is what holds it through the coil. On a watch band link, the surface you get after drawing is the surface that takes an even polish.
Thin, Wide, or Ribbed: Where the Route Changes
Two kinds of section make us slow down and plan the passes properly. Very thin and wide ones — a strip 0.5 mm thick and 12 mm wide — buckle under draw tension, so the sequence gets split into more, lighter passes with anneals in between. Ribbed sections and deep grooves collect die marks in the corner, so the finishing pass has to clean the corner out without wiping the radius you asked for.
This is why we ask what the part does, not just for the drawing. A dimension that is easy on a solid trapezoid can be the hard part on a ribbed profile at the same overall size, and the quote has to reflect it. It is also why we would rather see a sample of the wire you run today than a description of it.
When Rolling Alone Is the Right Answer
Being straight with you: if you need a plain flat or square section at ±0.05 mm, the surface is not critical, and the part is not cosmetic, rolling alone is cheaper and faster. We will quote it that way rather than sell you a drawn route you do not need. The combined route is for sections where the drawing says something the roll cannot hold.
Send us the section drawing with the control dimension marked, and tell us what the part does. We will tell you which route it needs and what that costs. You can see the shapes on the shaped wire pages, or start with custom shaped wire for sizes from 0.5 to 18 mm. Sales team is here and answers the same working day.
Contact info@ekwire.com for more information about our shaped wire and profile wire products.