A contact tip wears from the inside. Its bore goes oval and slightly oversize under arc heat, so the electrical contact with the wire becomes intermittent and the wire no longer emerges where it should.
The symptoms are an arc that wanders, more spatter than usual, and occasional sticking — at settings that welded cleanly last month. The tip will look almost new. Change it before adjusting anything on the machine: it is the cheapest part in the system and the commonest cause of what feels like a machine fault.
The questions welders ask
How long should a tip last?
A few hours of arc time in clean conditions, considerably less with rusty or dusty wire, and almost no time at all if spatter has been allowed to bridge the tip and nozzle. Keep a box of them — the reason people weld with worn tips is that they only own one.
Last reviewed 2026-08-14