TL;DR
Wire feed problems are usually a contaminated or kinked liner, worn drive rolls, or incorrect drive roll tension. Replace the liner first; it is the most common root cause.
What you might see
- wire stuttering or stalling during welding
- bird-nesting at the drive rolls
- wire burn-back into the contact tip
- inconsistent wire speed during a weld
Likely causes
Liner contaminated with metal shavings or worn inside diameter, causing drag and buckling
Drive rolls worn smooth or groove size mismatched to the wire diameter
Drive roll tension too high crushing soft wire, or too low allowing slippage
Contact tip bore worn, increasing resistance and causing wire to burn back
Required tools
- Replacement liner per Lincoln Power MIG gun model
- Replacement drive rolls (if worn)
- Replacement contact tip
- Wire cutters
- Combination wrench for drive roll hub nut
Safety first
- Keep fingers away from drive rolls during wire threading. The rolls are powered by the feed motor and can crush fingers if the trigger is accidentally depressed.
- Remove power before replacing the liner or drive rolls.
Procedure
- 1
Remove the MIG gun from the wire feeder. Pull the liner out from the gun end. Inspect it for kinks, metal shavings, or deformation.
- 2
Replace the liner with the Lincoln-specified liner for the gun model and wire size. Insert from the gun neck end and trim to the correct length per the Lincoln installation guide.[1]
- 3
Inspect the drive rolls. The groove size must match the wire diameter. Rolls with flattened groove walls or worn groove radii must be replaced.[1]
- 4
Set drive roll tension: tighten just enough so a hand-brake on the spool does not stall the feed. Too tight crushes soft wire; too loose causes slippage. Follow the Lincoln Power MIG operator tension guide.[1]
- 5
Thread the wire through the rolls and liner to the contact tip. Verify the wire exits straight with no kinks at the transition from rolls to liner.
- 6
Replace the contact tip if it is worn (see the inconsistent-arc guide on this machine). A worn tip is a frequent secondary cause of burn-back.
- 7
Make a test weld on scrap at the target wire speed. Steady, smooth wire feed and a stable arc confirm the repair.
Sources
Lincoln Electric Power MIG Industrial MIG Welder Operator Manual, Lincoln Electric
Lincoln Electric Power MIG Operator's Manual, wire drive system and liner replacement procedure (general)
View source
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Stop fixing the same fault twice.
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