Cold Heading Stainless Steel Wire - Soap Coating, Low Wear
Cold Heading Stainless Steel Wire
,Soap Coated Stainless Steel Wire
,Low Wear Cold Heading Wire
Cold Heading Stainless Steel Wire with Soap Coating for Stable Feeding
Product Introduction
The surface film on a cold heading wire does two jobs at the same time: it separates the wire from the cut-off tool, and it lets the feed rolls grip without slip. Both jobs are set by the coating system, not by the steel grade alone.
Our cold heading wire uses a borax carrier with a stearate soap film on top. Coating weight is stated in grams per square metre and checked by gravimetric test on every lot, so the friction condition at the press stays inside the window your tooling was set for.
Available from 0.15 mm to 12 mm, in 302, 304, 304Cu, 316L, 410 and 430, spheroidize annealed where the deformation ratio calls for it.
Product Specifications
| Parameter | Specification |
|---|---|
| Grade | 302, 304, 304Cu, 316L, 410, 430 |
| Diameter Range | 0.15–12 mm |
| Diameter Tolerance | ±0.02 mm up to 2.0 mm; ±0.03 mm above 2.0 mm |
| Coating System | Borax carrier with stearate soap film |
| Coating Weight | 2–8 g/m², customer specified |
| Tensile Strength | 550–750 MPa, annealed, grade dependent |
| Hardness After Spheroidize Anneal | ≤ 85 HRB, grade dependent |
| Surface | Bright, dry, oil-free option available |
| Straightness | ≤ 1 mm/m on cut lengths |
| Coil Weight | 100–500 kg |
| Reference Standard | ASTM A555, EN 10263-5, JIS G4315 |
Why the Surface Film Decides Press Behaviour
Friction at the Cut-Off Station
A film that is too thin lets wire and knife touch metal to metal. Tool wear rises and the sheared face starts to show a torn edge instead of a clean cut. A film that is too thick lowers the grip on the feed rolls, and cut-off length begins to scatter from part to part.
Feed Roll Grip
Stearate soap gives a higher friction coefficient than a plain borax carrier at ambient temperature. That is why high-speed presses running above roughly 150 parts per minute are usually set up with a soap film, matched to feed roll pressure and clean roll surfaces.
Coating Weight Versus Tool Life
The relationship is not linear. Beyond a certain film weight the excess is pushed ahead of the die and builds up at the entry, which changes the clearance condition. We therefore hold a stated weight window and monitor it by lot rather than adding film to chase tool life.
Coating Systems and When to Use Them
Borax Carrier Alone
Suited to heavy deformation where the wire heats up in the die, because borax keeps lubricating as temperature rises. It is hygroscopic, so coils need dry storage and sealed packing for sea freight.
Soap Film Over Borax
The most common combination. The soap carries the ambient-temperature part of the forming operation and the borax residue covers the points where temperature climbs.
Dry Film for High-Speed Presses
A thin dry film for plants that want clean parts before passivation, or that run fast headers where a heavy film would load the feed system.
Coating Weight Control and Inspection
Gravimetric Check
A measured length is stripped in a solvent or alkaline bath, dried and weighed. The mass difference divided by the surface area gives the coating weight in g/m². We record this value on the inspection sheet for each lot.
Adhesion and Coverage Check
The film must be continuous, with no bare metal and no powdery rub-off. A bend test on a short sample plus a wipe test shows whether the film is bonded or sitting loose on the surface.
Common Coating Faults and Their Causes
Bare Patches Along the Coil
Usually incomplete cleaning before coating, a low level in the coating bath, or line speed too high for the bath length.
Flaking at the Outer Diameter
Excess film weight combined with high coiling tension. The outer wraps are pressed together and the film cracks in storage.
Build-Up at the Pay-Off
Very heavy film or humid storage. The soap takes up moisture and the wraps start to bond, which shows up as jerky pay-off and variable cut-off length.
Applications
Screws and Machine Screws
Head forming and thread rolling on multi-station headers, where cut-off length repeatability drives thread quality.
Bolts, Nuts and Rivets
Two-blow and three-blow heading, including parts with a shank-to-head ratio that needs a fully annealed structure.
Cold-Formed Special Parts
Non-standard fasteners, insert nuts, and small structural parts where the forming sequence is long and die lubrication cannot be re-applied mid-stroke.
Product Advantages
- Coating weight held to a stated range and verified per lot, so feed and cut-off behaviour stays repeatable from coil to coil.
- Borax carrier with soap film works at ambient temperature and still leaves a lubricating residue where forming temperature rises.
- Spheroidize annealed structure available for high deformation ratios, keeping crack risk low in the head and thread zone.
- Diameter tolerance of ±0.02 mm up to 2.0 mm keeps cut-off length and die clearance consistent.
- Oil-free dry film option for plants that need clean parts before passivation.
Quality Control
Each lot is checked for chemical composition by optical emission, tensile strength and hardness, coating weight, diameter and ovality, and surface condition under magnification. A mill test certificate 3.1 is issued with the shipment, and retained samples are kept for twelve months for traceability.
Selection and Ordering Notes
- State the grade and diameter, and whether a spheroidize annealed structure is needed for your deformation ratio.
- Give the coating weight window in g/m². If it is not fixed yet, tell us the press speed and the head diameter and we will propose a range.
- Name the lubricant used at the press, because some oils strip the soap film on contact.
- Confirm coil weight and pay-off direction so the coil matches your feeding equipment.
- For parts that are passivated after forming, ask for the oil-free dry film option.
Send us your part drawing, grade and press speed, and we will match the coating weight and annealing condition to your forming process.
