Miller Feed Rolls FAQs
Answers to common questions about choosing, fitting and looking after MIG wire feed (drive) rolls.
How do I match the roll to my wire size?
Each groove is made for a particular wire diameter, so the roll must match the wire in the feeder. A groove that is too large lets the wire slip, and one that is too small squeezes or shaves it.
Most rolls have the size marked on the side, and many have a different size in each groove so the roll can be turned over. Rolls should also be changed when the wire diameter or the wire material changes. Check the size marking against the wire spool before you fit them.
How do I know when feed rolls are worn, and how often should I check them?
A sensible habit is to look at the rolls every time you fit a new spool of wire and replace them if needed. Signs of wear include a groove worn into one side, a groove that is rounded off or clogged, knurling that has flattened, and wire that slips or shaves even at correct pressure.
Knurled rolls generally wear out faster than smooth ones. If the groove looks worn, swapping the roll is usually a quick job and often cures erratic feeding.
Can I use steel feed rolls to weld aluminium wire?
Usually not. Aluminium wire is soft, and the choice of drive roll is a major cause of feeding problems with it. Rolls with a rough or sharp-edged groove, or rolls that are misaligned, shave fine particles off the wire, and these build up in the groove and liner.
For aluminium, use rolls made for soft wire, normally with a smooth U-shaped groove, set to the lowest pressure that feeds the wire. Many users also fit a liner made for aluminium. Follow the machine and wire makers' instructions.
My wire feeds badly or tangles at the rolls. What should I check?
Do not assume the rolls are the cause. Check the groove type and size against the wire, then the roll pressure. Then look downstream: a worn or blocked contact tip, or a dirty, kinked, wrong-size or wrongly trimmed liner, stops the wire while the rolls keep pushing, and the wire piles up at the rolls.
The liner should be a little larger than the wire and cut to the correct length. Replace it when buildup causes erratic feeding. Also check that the rolls line up with the inlet guide.