Kemppi Individual Feed Rolls FAQs
Straight answers to the questions people ask when choosing, setting up and replacing individual wire feed rolls.
What do feed rolls do?
Feed rolls grip the welding wire and push it from the spool, through the feeder and down the torch cable to the contact tip. The wire is pushed by a driven roll working against a pressure roll, and the groove in the roll is what holds the wire.
Because they feed the wire the whole time you weld, the grooves wear and the wrong roll type or size causes slipping, a flattened wire and an unstable arc. Choosing the right roll matters as much as choosing the wire.
Which groove type do I need for my wire?
It depends on the wire. V-groove rolls suit solid steel and stainless wire. Knurled V-groove rolls, which have small teeth to grip, suit flux-cored and metal-cored wires. Smooth U-groove rolls suit aluminium and other very soft wires. A U-cogged type exists for very soft cored wires.
The wrong type either slips or bites into the wire. Check the wire maker's recommendation and your machine manual before ordering.
How do I match the roll to the wire diameter?
The groove must match the wire diameter. A roll made for thicker wire will not grip a thinner wire and the wire will slip, while a roll that is too small can crush it. For example, a 0.9 mm wire needs a roll marked for 0.9 mm.
Check the size on the roll, the wire spool and your machine manual. If you are replacing a roll, read the size stamped on the old one, or the machine manual, and match the roll type to your wire as well.
How can I tell if my feed rolls are worn?
Worn grooves lose their shape and slip, even when the pressure seems right. Signs include uneven or hesitant feeding, wire slipping, bird-nesting and a build-up of metal shavings in the groove. People often raise the pressure to compensate, which then flattens the wire and clogs the liner.
Before replacing the rolls, clean them and check the liner, guide tubes and contact tip, because these cause similar faults. Replacing worn rolls as a matched set is good practice.