Spares and consumables for a lighter-duty, gas-cooled MIG torch, including liners for soft wires and nozzle options.
What liner suits aluminium or stainless wire?
Soft wires such as aluminium, and often stainless, are normally fed through a plastic or PTFE-type liner rather than a coiled steel one. These liners have lower friction, so the wire is less likely to catch, buckle or birdnest.
Stainless is sometimes run through a steel liner, so check what the wire and torch makers recommend. Match the liner bore to the wire diameter, because liners are sold for stated wire size ranges. Check the length against your cable too, and look at the torch manual for the liner type it is designed to take.
Why is a steel liner a poor match for aluminium wire?
Aluminium wire is soft and has little stiffness, so it bends and deforms easily under push. A coiled steel liner creates more drag, which can shave the wire, load the liner with debris and cause buckling and birdnesting at the drive rolls.
Steel liners can also leave traces of steel on the wire, which is undesirable for aluminium work. For this reason, many welders keep a dedicated soft-wire liner for aluminium. Mark your liners by wire type so the wrong one is not fitted by mistake, and change the liner when you change wire material.
How do I trim a new liner correctly?
Lay the torch cable straight and avoid twisting it while you cut, because torch cables are often helically wound and a liner trimmed while twisted can end up too short. A liner that is too short leaves a gap at the contact tip and can cause erratic feeding or birdnesting, while one left too long can kink.
Use a liner gauge if the torch maker provides one, and follow the manual. Plastic liners often need a clean, square cut and no burrs. After fitting, feed the wire through by hand and check it runs smoothly before welding.
How can I tell the liner needs replacing?
Signs include erratic wire feeding, an unstable arc, frequent burnback of the contact tip, a drop in current, and birdnesting. First remove the wire and blow clean compressed air through the liner with the cable straight, since debris is a common cause. If feeding is still rough, the liner is probably worn and should be replaced.
Check the liner last, because drive rolls, tip size and wire quality are common causes too. The liner should never carry welding current. If the cable is discoloured or unusually hot along its length, stop and have the torch cable repaired or replaced.
What does a tip adaptor do and when should it be replaced?
The tip adaptor holds the contact tip and passes current to it. It is a replaceable part so that the repeated changing of tips wears the adaptor rather than the torch neck. On some torch designs it also acts as the gas diffuser.
Replace it if the threads are worn or damaged, if the gas holes are blocked with spatter, or if the tip will not tighten fully. Adaptors do not interchange between torch styles, so match thread, length and design to your torch from the manual or the old part. Some adaptors are insulated, and the manual shows whether yours should be.
Why does a loose contact tip or adaptor cause problems?
Loose front-end parts make poor electrical contact, so they overheat. Signs are a tip that looks cooked or discoloured, burnt diffuser edges, and a liner that looks heat-damaged. Poor current transfer also makes the arc unstable.
Tighten the tip and adaptor firmly, following the maker's instructions, once the torch is cool. When the torch is cold or after changing consumables, recheck them. Gas flow also cools the front-end parts, so make sure the nozzle is clean and the flow is correct.