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Burnback happens when the wire melts back and fuses to the contact tip instead of feeding smoothly into the weld pool. The usual causes are a wire-feed pause, too much wire stickout, or settings that put heat into the wire faster than it can travel. It can ruin a tip, waste wire, and interrupt a weld—but the fix is often a small adjustment, not a new machine.
Recognize burnback before changing settings
Burnback leaves the wire stuck inside or at the end of the contact tip, often with a small ball of solidified metal. The gun may stop feeding, make a sharp pop, or keep the arc going briefly after the wire stalls. A tip that is simply worn usually causes erratic feeding or a wandering arc; burnback is more likely when the wire has fused to the tip.
Switch off the welder before clearing the tip. Let it cool, then remove the tip and cut the wire back to clean, straight material. If the tip bore is damaged, oval, or badly spattered, replace it. Do not force wire through a fused tip or try to weld with a partially blocked one.
Check wire feed and the gun path first
A brief feed interruption is a common trigger. Check that the spool turns freely and that the wire is not crossed or trapped under another wrap. Set the spool brake just tight enough to stop overrun when feeding stops; excessive brake tension makes the drive rolls work harder and can cause slipping.
Match the drive-roll groove to the wire type and diameter. The rolls should grip without crushing the wire. Too little pressure causes slip; too much can deform soft wire and create feeding problems. With the gun straight, squeeze the trigger and watch for a steady feed. Repeat with the cable in the position you use for welding. A sharply bent or twisted liner can drag wire, especially with aluminum.
Keep the gun liner and contact tip matched to the wire diameter. A worn liner, dirty liner, or incorrect tip can add resistance. Replace a liner if the wire feeds unevenly after you have checked the spool and drive rolls. For aluminum, use a liner and feed setup intended for the soft wire; a spool gun is often easier for longer or more demanding feeds, though it costs more than improving a short, straight push-feed setup.
Set stickout and arc settings sensibly
Stickout is the length of wire extending from the contact tip to the work. Too much stickout increases electrical resistance in the wire and can make the arc less stable; too little can overheat the tip and shorten the working distance. As a starting point for many short-circuit MIG setups, aim for roughly 10–15 mm (3/8–5/8 in) of wire stickout. Use the procedure recommended for your machine, wire, and transfer mode when available.
If the wire burns back as you stop welding, check the machine’s burnback or wire-burnback control. This setting determines how long the arc remains after the drive motor stops. Too much burnback time lets the wire melt back into the tip. Reduce it in small steps and test on scrap. Too little can leave a long wire tail that is awkward to restart.
Also check that voltage and wire-feed speed are a suitable pair for the material thickness and wire diameter. If wire feed is too slow for the selected voltage, the wire can melt back quickly. If feed is too fast, the wire may stub into the work. Use the machine’s chart as a starting point, then make small changes on scrap rather than turning several controls at once.
Choose the fix that matches the symptom
| Symptom | Likely cause | First fix | When to replace or upgrade |
|---|---|---|---|
| Wire fuses to the tip at the end of a weld | Burnback time too long, or feed stops before the arc | Reduce burnback setting slightly; check trigger and feed timing | Replace a tip only if its bore is damaged or blocked |
| Wire stalls during a weld | Spool drag, tight cable bend, dirty liner, or drive-roll slip | Straighten the cable; inspect spool tension and roll pressure | Replace a worn liner if feeding remains inconsistent |
| Wire sticks to the work, then melts back | Feed too slow for voltage, or poor arc start | Check the machine chart and adjust settings on scrap | Consider a machine with adjustable start or burnback controls if this happens often |
| Repeated feeding trouble with aluminum | Soft wire buckling or excessive liner drag | Use the correct liner, rolls, and short, straight gun path | A spool gun can be worthwhile for frequent aluminum work |
Replace consumables without guessing
Contact tips are inexpensive, so replacing a clearly damaged tip is reasonable. But a new tip will not fix a spool that drags or a liner that binds. Keep tips matched to the wire diameter and use the size specified for your torch. A small mismatch can cause poor electrical contact or excess wire drag. If you need replacements, compare a MIG contact-tip assortment in the correct wire diameter with individual tips; an assortment is convenient, but a single pack is usually cheaper if you use one wire size.
For a liner replacement, verify the torch model and cable length before buying. A compatible MIG gun liner is useful when the existing liner is damaged or contaminated, but replacing it as routine maintenance is unnecessary if the wire feeds smoothly.
Use a short test routine
Before a production weld, feed wire through the gun and make a short test bead on similar scrap. Keep the cable as straight as practical, use consistent stickout, and listen for smooth feeding and an even arc. If burnback occurs, change one thing at a time: first inspect the feed path, then check stickout and settings, and only then replace suspect consumables.
Do not keep welding through repeated burnback. Fused wire can damage the tip, and a blocked tip can make feed behavior less predictable. A few minutes spent checking spool drag, drive-roll pressure, cable bends, and burnback timing is usually cheaper than cycling through tips or buying a new torch.