Contact Tips FAQs
Straight answers to the questions people ask most when choosing, fitting and replacing MIG contact tips.
How do I know when a contact tip needs replacing?
Look at the hole the wire passes through. The first and clearest sign of wear is a bore that has gone from round to oval or egg-shaped. Other signs are an unsteady arc, wire that feeds erratically or sticks, more spatter than usual, heavy discolouration, or a tip that has fused after a burnback.
Change a tip because of its condition rather than on a fixed schedule or at every break. Do not try to file out the bore, as that roughens a precisely machined hole.
How do I choose the right size of contact tip?
The bore must match the diameter of the wire you are welding with. A tip that is too large lets the wire wander and can cause arcing inside the tip and faster wear. One that is too small makes the wire drag, stick or burn back.
If you run more than one wire size, keep a matching tip for each rather than using one oversized tip for everything. Wire diameter is marked on most tips, so compare it with your wire spool before fitting.
Do I need a different contact tip for steel, stainless steel and aluminium?
The bore must always match the wire size, but some makers also supply tips matched to the wire material and mark them accordingly. Tips for aluminium are often bored slightly larger than the nominal wire size, because aluminium wire is soft and tends to jam in a snug bore.
For steel and stainless the same standard tip style is often suitable, but check what your torch maker recommends. Aluminium also needs a suitable liner and drive rolls, not just the right tip.
What is a heavy-duty contact tip and when is it worth using?
Heavy-duty tips are usually a stronger copper alloy, such as chrome zirconium, or have a thicker body. They resist heat and wear better than plain copper, which is why they are often chosen for high-current or long-duration welding.
For light or occasional work a standard copper tip is normally adequate. Using a heavy-duty tip does not raise the torch's own current rating, so stay within the amps and duty cycle the torch maker states.