Liners FAQs
Straight answers on choosing, fitting and looking after the wire liner in a MIG torch cable.
What does a MIG torch liner do?
The liner is the guide tube that runs through the torch cable and carries the welding wire from the wire feeder to the contact tip. It supports the wire along the way so it does not buckle or snag, and a good one lets the wire run with little friction.
Because every metre of wire passes through it, the liner wears over time. A worn, dirty or wrong-sized liner is one of the most common causes of poor wire feeding and an unsteady arc, so it is worth checking before blaming the machine.
Which liner do I need: steel or plastic?
Steel (coiled) liners are strong and resist buckling, and are normally used for steel wire. Aluminium and other soft wires feed better through plastic liners, such as PTFE, which have a smooth bore with less drag. Some makers also use other plastics for short, straight runs at lower duty.
Steel liners are generally avoided for aluminium, because the wire can pick up traces of steel and the rough bore causes drag. Check the wire type in the torch manual and choose the liner designed for it.
How do I match the liner to my wire diameter?
Each liner is made for a range of wire sizes. A bore that is too large lets thin wire wander and buckle, which causes poor feeding and wears the liner out faster. One that is too tight adds friction and drag.
Check the size range printed on the liner or its packaging against the wire on your spool, and change the liner when you move to a different diameter. Matching the liner to both the wire size and the wire material gives the smoothest feed.
What do the liner colours mean?
Many makers colour-code liners by wire size, often with coloured shrink wrap or end caps, so you can tell sizes apart at a glance. Some makers use the same colour on the feed rolls for the same wire diameter.
However, the colours and the ranges they cover differ between makers, and even between product lines, so never rely on colour alone. Read the wire size range printed on the liner or its packaging and check it against your torch manual or the maker's selection table.