Common wire drawing line problems and how to solve them

Almost every problem on a wire drawing line becomes visible in the same place: at the die. The wire breaks at the die, the die wears early, the die runs hot, the scratch is noticed as the wire exits. That visibility is misleading, because where the symptom appears and where the problem was born are usually not the same. The die is the last point at which the output of all preceding stages is read. A mistake in surface preparation is invoiced at the die.

This guide takes the seven most frequently reported problems and treats each in the same layout: symptom, likely causes, what to check. The aim is not to give a fixed recipe but to let an engineer work from the symptom and quickly narrow down which stage of the line to examine. Along the reference sequence (degreasing → rinsing/activation → zinc phosphate → drawing soap → drawing) we have marked which symptom each stage can be responsible for; where you want more depth, you will find a link to the relevant article.

1. Wire breaking at the die

Symptom: the wire breaks at a particular die or at random stages. If break frequency increases through the shift, the problem should be sought in the line itself rather than in the material.

Likely causes:

• The lubricating film failing to establish at the die entry: inadequate coating weight or soap not being carried to the surface.
• A worn or ovalised die, or one with pick-up inside it.
• An uneven reduction distribution in the pass schedule; excessive area reduction falling on a single die.
• Defects originating in the wire rod: surface cracks, laps, slag inclusions, out-of-tolerance section.
• Misalignment or a faulty guide roller preventing the wire entering the die axially.

What to check:

1. Determine whether the breaks concentrate at one die. If they do, look at lubrication and mechanical setting; if they are scattered, material becomes the stronger possibility.
2. Look at the wire surface before the die: is the layer matt, continuous and adherent? Bare, bright bands mean the film has not been established. Verify coating weight with the method in coating weight measurement; for KİMSOL zinc phosphate the typical band is 3–15 g/m².
3. Remove the die in question and inspect the entry cone and the bearing area. If there is pick-up or oval wear, change the die — but keep looking for the cause in lubrication.
4. If the reduction at the stage where breaks occur is high relative to its neighbours, rebalance the pass schedule.
5. If brittle-looking breaks recur, question the wire rod batch; this is not a problem that line settings will solve.

2. Die life shorter than expected

Symptom: dies grow in size, ovalise or show scoring in the bearing area before reaching their defined target. Dimensional deviations and downtime rise along with die change frequency.

Likely causes:

• Abrasive residue left on the wire surface: salts remaining from inadequate rinsing, loose phosphate sludge settled on the surface.
• A dusting phosphate layer that has not keyed into the surface; free crystals carried into the die.
• Soap becoming abrasive through metal swarf and wear particles mixing into the soap box.
• The lubricating film staying thin; increased metal-to-die contact and adhesive wear.
• Misalignment or vibration in the die holder; one-sided wear.

What to check:

• Measure the conductivity and overflow rate of the rinse stages. A saturated rinse leaves residue on the wire.
• Review the sludge in the bath; suspended sludge settles onto the wire. For methods see phosphate sludge management and phosphate bath maintenance.
• Check whether the layer is dusting: if running a dry cloth over the wire leaves noticeable grey dust on the cloth, adhesion is weak.
• Look at what is in the soap box; metallic glitter or hard grains show the soap is contaminated.
• Examine the symmetry of the wear. One-sided wear points to misalignment; symmetrical, rapid growth points to a lubrication or residue problem.

3. Scratches, scuffing and galling on the wire surface

Symptom: longitudinal scratches in the drawing direction, bright friction bands, and in severe cases material transfer from the die. Pick-up is seen inside the die and motor current rises. This picture is the clearest evidence that the film has been interrupted and metal and die are in direct contact; the friction regime has shifted from boundary lubrication to dry contact. We covered the mechanics of that transition in friction in cold forming.

Likely causes:

• The soap film forming discontinuously: inadequate coating weight or soap not being carried to the die entry.
• Coarse phosphate crystals; a porous structure unable to hold the soap and a layer that breaks up during forming.
• A degraded die entry cone; soap not being dragged into the die throat.
• Line speed and reduction too high for the softening behaviour of the soap.
• A patchy, locally missing layer due to inadequate degreasing; bare areas entering the friction zone.

What to check:

1. Find at which stage the scratching starts. Take and compare samples between passes; galling almost always starts at a single die and is carried on from there.
2. Inspect the entry cone and bearing area of that die; if there is pick-up, change the die.
3. Check by hand whether a tunnel has opened in the soap box. The box may look full while the wire contacts a hard crust; the detail is in dry drawing soap film stability.
4. Verify the crystal appearance; a fine, densely crystalline layer carries soap better. For the effect of activation see the activation bath and crystal size.
5. Re-assess whether the soap type suits the line speed and pass schedule; the selection logic is in drawing soap selection.

4. Soap film not keying in, and dusting

Symptom: the soap does not stay on the wire surface; it falls off along the line and dust builds up at the die exit and on the capstans. For soap to stay on the surface it needs something to key into, and that something is the porous crystalline skeleton of the phosphate layer. If the soap is dusting, the problem is usually not the soap itself but the carrier surface beneath it.

Likely causes:

• Coating weight below the target range; the surface lacking the pore volume to hold soap.
• A coarse, large-crystalline phosphate structure; a weak or exhausted activation stage.
• The soap taking up moisture: hygroscopic powder or granular soap cakes and transfers unevenly to the surface.
• Crusting and tunnelling in the soap box; the wire contacting a hard surface instead of loose powder.

What to check:

• Verify the phosphate side first: coating weight, crystal appearance and adhesion. If the phosphate is weak, no change on the soap side will give a lasting result.
• Check the renewal interval of the activation bath. An exhausted activation leads to coarse crystals and weak adhesion.
• Confirm that soap packs have not been left open and that storage is dry and cool. Do not feed caked soap to the line.
• Fill the soap box by emptying and cleaning it completely rather than topping it up. Crusted soap does not turn back into loose powder.
• If dusting persists once all this is in place, re-assess the right soap character for your line within the Kimkal range with the technical team.

5. Coating weight fluctuating from batch to batch

Symptom: with the same product, the same line and the same recipe, coating weight varies between batches; some coils draw without trouble while others break at the same dies. Coating weight is not the product of the phosphate bath alone; the source of the fluctuation is usually not in the bath but in the variability of the surface arriving at the entry.

Likely causes:

• Changing degreasing efficiency: the bath saturating with oil, temperature or concentration falling, contact time shortening.
• Differences in the starting condition of the wire rod surface: different supplier, different waiting time, oxide or light rust on the surface.
• The activation bath becoming exhausted or contaminated; nucleation density falling.
• The acid balance drifting in the phosphate bath, or the accelerator level falling.
• Bath temperature and contact time differing between batches; effective concentration falling through sludge accumulation.

What to check:

1. Put total acid and free acid on the shift routine. In KİMSOL zinc phosphate baths the typical range is total acid ≈40–60 points and free acid ≈5–8 points; the real issue is holding these values steady between batches.
2. Record bath temperature (60–80 °C) and contact time (5–15 min). A temperature drop is the most frequently missed cause of fluctuation.
3. Monitor the concentration, pH and temperature (40–70 °C) of the degreasing bath.
4. Look at whether water forms an unbroken film on wire leaving degreasing. Beading water shows the oil has not been fully removed.
5. Measure coating weight to a defined sampling plan and follow it as a trend. A single measurement gives no information; a trend does.

6. Rust and staining on the wire surface

Symptom: phosphated wire shows brown-red staining, spot rust or irregular colour differences before drawing or while waiting in intermediate stock. Sometimes it appears only on the outer windings of the coil, sometimes across the whole surface.

Likely causes:

• Inadequate rinsing after phosphating; residue left on the surface starting corrosion in the presence of moisture.
• Incomplete drying; moisture trapped between the windings.
• Low coating weight or a discontinuous layer; inadequate corrosion resistance.
• A damp, open intermediate storage area and coils in contact with cold floors; condensation.
• An excessively long wait between phosphating and drawing.

What to check:

• Measure the conductivity and refresh rate of the final rinse water. A saturated rinse is the most common cause of rust.
• Check the temperature and time of the drying stage; verify that drying reaches the centre of the coil.
• Review the intermediate storage area: coils should not be in direct contact with the floor or left in a condensing environment.
• Define the waiting time between phosphating and drawing; assess coils exceeding it separately. The subject is covered in why phosphated wire rusts.
• If the staining concentrates in particular areas, go back to the degreasing side: a surface that cannot be cleaned locally will also be coated only locally.

7. Die overheating

Symptom: one or more dies get too hot to touch, discolouration appears on the die holder, motor current rises. Heating is not a cause but a consequence: the heat generated at the die has two sources, the work of plastic deformation and friction. The deformation share is set by the pass schedule, the friction share by lubrication. A single die running noticeably hotter than the others almost always shows that lubrication has been interrupted at that stage.

Likely causes:

• The lubricating film failing to establish at that stage; the friction coefficient rising.
• Pick-up or wear inside the die; the rubbing surface area increasing.
• Excessive reduction falling on that die in the pass schedule.
• Cooling water flow rate dropping, the line blocking, or inlet temperature rising.
• Line speed being increased while cooling and lubrication conditions are left unchanged.

What to check:

1. Compare temperatures die by die. If one die stands out, examine lubrication at that stage first.
2. Verify the cooling circuit: flow rate, blockage in the line, cooling water inlet temperature.
3. Remove the die and inspect it for pick-up and wear; distinguish whether the heating comes from the die or from the film.
4. If the area reduction at that die is high relative to its neighbours, rebalance the reduction distribution.
5. Monitor whether enough soap is reaching the hot die; for the approach see reducing drawing soap consumption.

Trying to cool an overheating die is suppressing the symptom. If the heat is being generated because lubrication has been interrupted, more cooling water only delays the moment the problem becomes visible.

In summary: read the symptom at the die, look for the cause up the line

All seven problems share a pattern: the symptom emerges in the drawing zone while the cause usually lies further upstream — in degreasing, in activation, in the phosphate bath or in the soap box. Set your troubleshooting order in reverse: before changing the die, look at the film; before looking at the film, look at the carrier surface; before looking at the carrier surface, look at how the surface was prepared. Changing the die is usually the quickest but shortest-lived fix.

If you would like to assess the coating weight target and soap character together for your line speed, pass schedule and material conditions, talk to our technical team. Producing phosphating chemicals and drawing soaps since 1982, Kimfosan provides process support tailored to field conditions from its plant in Kartepe / Kocaeli; for product and application documents see the document centre.