Flexlite GF 303G Parts FAQs
Practical answers on choosing and looking after the front-end parts, neck and liner of a gas-cooled MIG torch.
Does the contact tip material matter for steel, stainless and aluminium wire?
It can. Tips are usually made from electrolytic copper or from a harder copper alloy. Electrolytic copper conducts very well but softens at lower temperatures, so it suits lower currents. A harder alloy tip usually lasts longer at medium to high current and with rough or abrasive wire. Tips made for aluminium wire normally have a slightly larger bore, because aluminium wire expands more when heated, so use a tip made for the wire you run.
The wire diameter and the thread are the first things to match. Check the torch manual or the markings on your old tip for the thread and bore before choosing the material.
Why do flux-cored wires wear contact tips faster?
Cored wires and some uncoated wires have a rougher surface than a smooth copper-coated solid wire, so they scour the bore of the tip as they pass through. The bore then opens up, the arc becomes unstable and wire may wander or burn back.
If you switch to a cored wire, expect to inspect and change tips more often, and consider a harder alloy tip. Keep the liner clean and the tip tight, because worn or loose parts add to the heat load. Your wire supplier's guidance and the torch manual will say which tip suits the wire you use.
How can I tell my gas-cooled torch is overheating?
Common signs are a handle that vibrates with the arc length changing quickly, heat that you can feel travelling back through the neck and handle into the cable, and a blue or oxidised look at the end of the liner. Running for too long at high current is the usual cause. Other causes include consumables sitting too close to the weld pool (short stickout or a flush tip), mixed shielding gas, which tends to run hotter than carbon dioxide, and a poor or distant work clamp.
Try shorter weld periods, a better placed clamp, a longer stickout or heavier-duty front-end parts. If it keeps happening, the job may need a torch with a higher rating. Always follow the maker's ratings and your risk assessment.
How should I fit and trim a liner so wire does not burn back?
Follow the instructions supplied with the liner and the torch manual. A liner that is too short or badly seated is a known cause of wire burnback and feed problems, and cutting too short is the most common cause of early liner wear. Lay the torch cable out straight before measuring and cutting, rather than copying the old liner, which may have been cut wrongly. Cut square and remove any burr from the end.
The front end of a steel liner is usually finished at an angle so that it sits centrally in the seat at the back of the contact tip. A liner that looks fused or shows melted ringlets at the end has overheated, so look for the cause as well as changing it.