LGS3 150G Mig Torch Parts FAQs
Consumables and wear parts for a light-duty, gas-cooled MIG torch: contact tips, nozzles and wire liners, and how to choose and look after them.
How do I know when a contact tip is worn?
The main sign is the bore. A new tip has a round hole; a worn tip has a hole that has become oval or egg-shaped, or noticeably larger than the wire. Wire friction wears it, and heat speeds that up. A tip with wire fused into it after a burnback should be replaced too.
Symptoms include an unstable arc, poor starts, wire that sticks or feeds unevenly and more spatter. Spatter or blackening on the outside is not by itself a reason to change a tip, so inspect the bore rather than changing tips by habit. Compare it against a new tip if you are unsure.
Do I need a different contact tip for aluminium wire?
Often, yes. Aluminium wire is soft and expands with heat, so a tip for aluminium usually has a slightly larger bore or a design made for aluminium, to stop the wire binding. Using a tip sized for steel on aluminium wire can cause sticking and burnback.
Check the tip marking against the wire size and follow the torch and wire maker's recommendation. Aluminium also needs a suitable liner and the correct drive rolls, so treat the tip as one part of a set-up. Keep tips for aluminium separate from those used on other wires, so that you do not mix them up. Details depend on the equipment, so check your manual.
What are the differences between nozzle shapes?
Conical nozzles give good gas coverage with a clear view of the weld, and suit much manual welding. Cylindrical (straight) nozzles have a large straight bore and are commonly used at higher currents, but give less access in tight spots. Bottle-shaped and tapered nozzles have a narrower tip for better access, but gas coverage is tighter and more easily disturbed by draughts.
As a guide, use the largest bore that still lets you reach the joint. Choose the shape that fits your torch and the joints you weld most often. Check the nozzle matches your tip and diffuser.
How do I look after nozzles, diffusers and O-rings?
Remove spatter from the nozzle regularly so it does not disturb the gas flow. Anti-spatter products help, but use them sparingly, because too much gel can clog the diffuser and block the gas. Nozzles often wear more from cleaning than from welding, so avoid rough tools that damage the bore.
Check the O-rings regularly and replace any that are cracked, flattened or missing, as they seal the gas. Replace nozzles with damaged threads or cracked inserts, which usually come from overheating. Always let the torch cool before handling consumables.