Cold Heading Lubricants: How to Trial a Change
When a cold heading lubricant changes, compare the new run with an accepted run on the current tooling before changing the die specification. Record the incoming wire surface and the lubricant applied on the machine separately. The trial should show which condition changed and where the first difference appeared.
Identify what changed at the forming station
Wire can arrive with a surface treatment and a lubricant from an earlier operation. The header may apply another lubricant during forming. A lubricant trade name alone leaves the incoming surface, application point and other products in the sequence unspecified. Ask the wire supplier what is on the delivered wire and ask the lubricant supplier which stage the proposed product is intended for.
A study of drawing, extrusion and cold heading evaluated lubrication at multiple steps, including the phosphate and soap treatment and additional lubricants. Cold-forging lubricant experiments published by Ngaile and colleagues compared alternatives to zinc phosphate precoat under defined test conditions. Use these studies to frame the trial and confirm suitability on the actual line.
Build a comparison that can guide a tooling decision
| Record | What to capture |
|---|---|
| Accepted baseline | Wire lot and surface preparation, machine lubricant, tool revision and condition, station and accepted parts. |
| Trial change | The proposed wire treatment or machine lubricant, where it is applied and any unavoidable changes in wire, speed or setup. |
| Station evidence | Label the first affected intermediate part and retain a corresponding baseline part. Record where marks or incomplete fill first appear. |
| Tool and part checks | Compare pickup on the same working surfaces and part measurements at the same locations. Include machine load records when comparable data are available. |
Keep the die geometry and wire lot constant where practical and record every difference that cannot be avoided. If the new wire and its surface treatment arrive together, record them as a combined change. A short trial can show initial part quality and visible pickup. A claim about tool life needs longer observation under agreed production conditions.
When should the die specification be reviewed?
If the comparison points to a repeatable issue at one station, send its incoming and outgoing samples, die drawing and the trial record. The supplier can then review the working surface, support and geometry alongside the lubrication change.
See Jungu's bolt forming die and bolt and screw tooling range. For station documentation, use the forming sequence guide.
Send the die drawing and lubricant comparison record to Jungu for a tooling review.