Troubleshooting guide › Process troubleshooting › Submerged arc welding problems
Submerged arc welding gives deep penetration and clean, spatter-free beads at 600-1200 A, but everything happens under the flux where the operator cannot see it. The bead that comes out of the flux is the only feedback. This page explains what each bead fault means, how current, voltage and speed interact on SAW, and the tractor and machine faults that look like welding faults.
Reviewed by the Cruxweld technical team, October 2026. Settings are starting points to confirm on a test piece; acceptance is decided by the code or drawing the job is built to. Checks marked “call” are for our technical team.
| Change | Effect on the bead |
|---|---|
| Raise current | Deeper penetration, bead wider and higher, more flux consumed |
| Raise voltage | Wider, flatter bead, less penetration and reinforcement, more flux melted, better slag release on rough plate |
| Raise travel speed | Narrower bead, less penetration, undercut above the limit |
| Longer stick-out | More deposition, less penetration, bead higher; too long gives overlap |
| Wire off-centre | One side undercut, the other overlapped; slag trapped; root missed |
Change one thing at a time and run a short test seam after each change. Set current for penetration first, then voltage for bead width, then speed for the size.
| Wire diameter | Current range | Characteristic |
|---|---|---|
| 2.0 mm | 200-400 A | Flat (CV) |
| 2.4 mm | 300-500 A | Flat (CV) |
| 3.0 mm | 350-600 A | Either: 3.0 mm is selectable in both modes on the CSW machines; use the mode the feeder is set to |
| 4.0 mm | 500-800 A | Drooping (CC) |
| 5.0 mm | 700-1000 A | Drooping (CC) |
| 6.0 mm | 820-1200 A | Drooping (CC) |
Typical ranges; the wire and flux combination sets the final values.
Damp flux is the first suspect; then dirty or rusty plate, rust or drawing lubricant on the wire, and a flux layer too thin so air reaches the arc.
Travel too fast for the current, current or voltage too high, wire off the joint centre.
Stick-out too long, voltage too low, groove too narrow, wire off-centre.
Backing bar pressing too hard or badly fitted, root gap too wide.
Current too high, travel too slow, root gap too large, backing not tight.
Voltage too low, bead too convex, wrong flux for the joint, plate rusty.
Deep narrow bead (depth more than the width), high sulphur in the plate, no run-off tabs so the end of the seam cracks as it shrinks.
Previous layer not cleaned, wire misaligned on the final pass, flux trapped against an unmelted sidewall.
Current too low, speed too high, voltage too high, wire misaligned, mains voltage sagging at peak hours.
Feed rolls slipping, contact tip worn, speed drifting, flux depth varying.
| Symptom | Likely cause | What to do |
|---|---|---|
| Hard arc starting | Contact tip burnt, wrong wire diameter selected on the panel, stick-out wrong, wire end not touching clean plate | Replace the tip; select the wire size; bring the wire 3-5 mm from the plate before start; cut a sharp wire end |
| Wire will not feed down while touching the plate | Wire-touch protection active | Lift the wire, or hold the feed switch for more than 3 s to override |
| Welding stops after about 20 s with no arc | Automatic shutdown: arc did not strike, or current was lost | Check earth, tip, wire contact; restart |
| Unstable voltage during the weld | Burnt tip, feed roller worn or not pressed, poor earth, earth cable too long | Replace tip, set roller pressure, shorten and clean the earth |
| Tractor travel uneven | Wheel loose, clutch slipping, rails or plate dirty, hoses dragging | Tighten wheels, check clutch, clean the track, support hoses |
| Tractor will not start | Control cable (14-core) damaged, start button, control box board | Check the cable and plug; call service for the board |
| Slow wire feed only after start | Poor negative cable contact, source fault | Clean and tighten the earth; call service |
| Current out of control | Control cable damage, machine fault | Isolate; call service |
| Fault code E19 (thermal) | Ambient over 40 degrees C, fan failure, temperature relay | Run the machine off-load to cool; check the fan |
| Fault code E43 (communication) | Loose or broken control cable, overload protector tripped on the feeder or travel motor | Reseat the cable; reset the overload after clearing the cause |
| Fault code E18 (feedback line) | Voltage feedback wire broken or positive cable not connected | Check the feedback lead and the output connection |
| Fault code E70 (short circuit on mode change) | Torch or head touching the work when switching SAW to MMA | Lift the head clear and retry |
Fault codes shown are typical of Cruxweld inverter SAW machines; other codes are explained by our technical team.
| 10 mm square-edge butt, one side | 550-650 A, 30-32 V, 50-60 cm/min |
| 12 mm fillet, 8 mm leg | 500-600 A, 28-30 V, 45-55 cm/min |
| 20 mm single V, fill passes | 600-700 A, 32-34 V, 40-50 cm/min |
| Stick-out | 25-35 mm (about 8 times the wire diameter) |
| Flux depth | 25-40 mm |
| Wire position (fillet) | Pointing at the root, 1-2 mm off the vertical plate, torch 40-45 degrees |
Starting points for mild steel with a general-purpose flux. Confirm on a test seam.
Usually the mains voltage is sagging under the load, or the contact tip is wearing and the stick-out is growing. Watch the voltmeter and replace the tip.
Flat (constant voltage) with wire up to 3 mm: the feeder runs at a set speed and the current follows. Drooping (constant current) with 3 mm and above: the current is set and the feeder adjusts speed to hold the arc voltage. Select the one the wire size needs.
Light rust and mill scale are tolerated by fused fluxes at high current. Heavy rust gives porosity on any process; grind it.
Lamps, fault codes and the checks an operator can do outside the cabinet, for the machines this page applies to.
SAW results depend on the power source holding the set current and voltage for hours at 100 % duty cycle, and on the tractor keeping a constant speed and wire position. A machine with voltage compensation and a flat (constant voltage) characteristic for wire up to 3 mm, and a drooping (constant current) characteristic for 3 mm and above, covers the normal range. Fault codes on the display save a lot of guessing.
Send a photo of the weld or cut, your machine model, consumable and plate thickness. Our technical team replies on WhatsApp with the likely causes and the next checks to make.
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