Fe35 FAQs
Straight answers to the questions people ask when choosing and replacing consumable parts for this class of MIG torch.
How do I know when to change a MIG contact tip?
Look at the hole in the tip. A new one is round; as it wears it becomes oval or enlarged, and the arc starts to wander, the wire feeds unevenly or it keeps burning back into the tip. A tip clogged with spatter at the entrance also makes feeding harder.
Inspecting the tip before each welding session is a good habit, and heavy use wears tips faster. Change it as soon as the bore is no longer round rather than waiting for it to fail.
How do I choose the right size of contact tip?
The bore should match the wire diameter, with just enough clearance for the wire to feed smoothly. A tip that is too large loses steady electrical contact and tends to cause burn-back; one that is too tight can jam the wire.
Tips are sold for each wire size, and also for each thread and torch type, so check both the wire diameter you use and the thread on your torch before choosing. Your torch manual will list the correct tip.
Why is there a separate contact tip for aluminium?
Aluminium wire is soft and expands more than steel as it heats, so aluminium tips are made with a slightly larger bore to stop the wire jamming and tangling in the feed system. Using a tip made for steel with aluminium wire can give poor contact and feeding trouble.
Buy tips marked for aluminium, and keep them separate from the tips you use for steel so they do not get mixed up. Check the torch maker's recommendation for the wire size you are using.
What types of gas nozzle are there and which should I choose?
Cylindrical nozzles give the widest gas coverage and suit higher currents and larger contact tips. Conical and tapered nozzles narrow towards the end, which gives better access in tight corners and T-joints but may collect spatter more quickly.
A sensible rule is to choose the largest nozzle that still lets you see and reach the joint. Make sure the nozzle is the type designed for your torch, because threads and fittings differ between torch families.