Bright Steel / CD
Cold Drawing
Cold drawing is the process of pulling hot-rolled steel bars through a die at room temperature to improve dimensional tolerance, surface quality, and mechanical properties. It is the most common bright bar production method.
Technical Specifications
Key Features
- Precise dimensional tolerance (h9/h10/h11)
- Improved surface quality (Ra 0.8 - 3.2 µm)
- Enhanced tensile strength and yield strength
- Smooth surface suitable for CNC and automatic lathes
- Chamfering and cut-to-length service
- Fast machining on high-speed machines
- Low scrap rate - material savings
- Raw surface suitable for coating processes
- Wide profile range (round, hexagon, square, flat)
- Defect-free products for safety-critical parts
Applications
- Automotive parts (shafts, pistons, axles)
- Hydraulic and pneumatic cylinder bodies
- CNC automatic lathe machining
- Machine manufacturing industry
- Bolts, nuts, and fasteners
- Furniture and appliance components
- Gear and bearing shafts
- Agricultural machinery parts
Dimension Table
| Profile | Size Range (mm) | Tolerance | Standard | Surface (Ra) |
|---|---|---|---|---|
| Round | 4 - 20 | h9 | EN 10278 | ≤ 1.6 µm |
| Round | 20 - 50 | h9 | EN 10278 | ≤ 2.0 µm |
| Round | 50 - 90 | h10/h11 | EN 10278 | ≤ 3.2 µm |
| Hexagon | 6 - 30 | h9 | EN 10278 | ≤ 1.6 µm |
| Hexagon | 30 - 70 | h10/h11 | EN 10278 | ≤ 2.5 µm |
| Square | 8 - 30 | h9 | EN 10278 | ≤ 2.0 µm |
| Square | 30 - 60 | h10/h11 | EN 10278 | ≤ 3.2 µm |
| Flat | 10x5 - 80x20 | h11 | EN 10278 | ≤ 3.2 µm |
| Flat | 80x20 - 150x30 | h11 | EN 10278 | ≤ 3.2 µm |
Technical Notes
- 01Cold drawing increases tensile strength by 15-20%.
- 02h9 tolerance is applied as standard for diameters below 50mm.
- 03For diameters above 50mm, h10 or h11 tolerance is preferred.
- 04Flat profiles have separate tolerances for width and thickness.
- 05Standard length: 3000-6000mm, custom cutting available on request.
- 06Chamfering provides easy feeding into automatic machines.
- 07Cold drawn products should be selected prior to heat treatment.
Steel Grades
What is bright steel?
Bright steel is hot-rolled bar finished cold — by cold drawing, peeling/turning or grinding — to a precise size and clean surface. Typical tolerances: h9/h11 for cold drawn, h6–h9 for ground bar (ISO 286). With its scale-free bright surface, tight tolerance and straightness, it often needs no further machining (EN 10277).
Cold drawing vs peeling vs grinding
Cold drawing: the bar is pulled through a die; strain hardening raises yield strength by ~10–20% and gives h9/h11 tolerance — the most economical bright product. Peeling (turning): the surface layer is machined off, removing surface cracks and decarburization without adding residual stress — ideal for large diameters and Q&T grades. Grinding: the tightest tolerance (h6–h9) and the best finish (Ra ≤ 0.8 µm) — for shafts and pins. Typical grades: C45, 42CrMo4, 11SMn30, 16MnCr5.
Frequently Asked Questions
Bright steel vs hot rolled — what is the difference?+
Bright steel is cold finished: scale-free surface, h6–h11 tolerance and high straightness; hot rolled has scale and wide tolerances and is usually bought for further machining.
Does cold drawing increase strength?+
Yes; strain hardening typically raises yield strength by 10–20%, with slightly reduced ductility. Stress-relief annealing is applied where needed.
When is peeled (turned) bar preferred?+
For large diameters, quenched-and-tempered grades, and when surface defects/decarburization must be fully removed — it gives a clean surface without adding residual stress.
Which tolerances are standard for bright steel?+
h9 or h11 for cold drawn, h6–h9 for ground bar (ISO 286-2, EN 10277).
Related Blog Posts
Technical articles, guides and industry analyses
C45 vs 42CrMo4 Steel: Carbon or Alloy — Which to Choose?
We compare C45 (1045) carbon steel with 42CrMo4 (4140) chrome-moly quenched & tempered steel by hardenability, strength, welding and cost — which to choose and when?
Quenched and Tempered Steels: EN 10083 Grades, Values and How to Choose
Quenched and tempered (Q&T) steel is the class that delivers strength and toughness together. We put the six main EN 10083 grades — C45, 25CrMo4, 42CrMo4, 39NiCrMo3, 34CrNiMo6, 51CrV4 — into one table with chemistry, section-dependent values and selection criteria.