Knowing when to change your liner:
The thing we often oversee, and here’s why………
First, what is a liner? Liners are a tightly wound spring that run the wire from your wire feed unit up to the handpiece and through to the tip. The liners are wire size and wire material specific.
Different types of welding wire take different liners.
Everyday mild steel wire uses a wound steel wire liner. They are sturdy and flexible and have a good life.
Aluminium wire uses a softer liner like kevlar or teflon. The aluminium wire is soft so the liner has to be soft as well. Say you were to use a standard steel liner, it would then cause the welding wire to wear down as it moves through.
Liners handle a range of sizes of wire, eg 0.6 – 0.9 wire. The next liner might take 1.0 – 1.2. Depending on the brand of your gun.
It is difficult to determine when the liner is worn out and requires changing. There is no visible way to tell on the outside if they have reached the end of their life. You can usually only diagnose a worn out liner by symptoms. Common symptoms are, vibration in the handpiece, birdnesting, erratic feeding.
A liner under normal use will wear out in 2 places first…
One place is straight out of the welding machine and the other is in the swan neck/bend on the handpiece. The liner will wear out on the outside of the bend, much like a river wears away the outside of the bank when it bends. Once they do this you will start to see the symptoms listed above
When you are having feed problems and you have checked your wire tension, changed your tip, the liner is your next port of call. They are cheap at less than $20 and take about 25mins to replace depending on your level of experience.
If you are experiencing feed problems, check you wire tension and your contact tip. After that it might be time to consider changing your liner!