Stage 01 · Surface
Mill scale off, phosphate coat on — the surface is prepared for the die.
Overview
Hot-rolled wire rod leaves the mill covered in mill scale — a hard, brittle layer of iron oxides formed as the red-hot rod cools in air. Drawn as it is, that scale would tear the carbide dies and score the wire. So before anything else, each coil is chemically cleaned and given a coating that will carry lubricant into the die.
How the line works
The crane carries each coil down the line, dipping it bath by bath.
Why it matters
01
Scale destroys dies
Iron oxide is harder than steel. Left on, it acts like grit in the die, wearing it fast and leaving scratches on the wire.
02
Lubricant needs a carrier
A bare steel surface cannot hold drawing soap under high pressure. A crystalline phosphate layer soaks up the lubricant and carries it through the die.
03
Clean surface, clean part
For cold heading and forging, any surface defect on the wire becomes a crack on the finished part. Pickling is the first line of defence.
Step by step
- 01
Acid pickling
Coils are lowered by crane into acid tanks. The acid dissolves the oxide scale and exposes clean steel.
- 02
Rinsing
Coils are rinsed in water to stop the reaction and remove acid and loosened scale.
- 03
Phosphating
A phosphate bath grows a fine crystalline layer on the steel — the lubricant carrier for drawing.
- 04
Neutralising & coating
A final neutralising / lime-type coat protects the surface and helps lubrication.
- 05
Drying
Coils are dried so the coating sets and no moisture reaches the furnace or the die.
Enquiries
We come back with availability and a quotation — usually the same working day.