What to do if you have problems with the contact tip constantly burning out during welding. Komarov Artem noted that there are welders who use 8 to 10 contact tips a day.
You must remember that a contact has two different and competing purposes. First, we must be able to smoothly pass a wire of the desired diameter through the hole in the contact tip. Of course, you can’t feed a 0.12 cm diameter, pass the wire through a 0.12 cm diameter hole, so manufacturers make the hole diameter slightly larger than the wire diameter.
While it is true that an even larger opening would allow smoother wire feeding, this would make it difficult for the contact to achieve its second purpose, which is to transfer the welding current reliably and consistently to the filler wire. This requires good electrical contact between the tip and the wire, which means we want the hole to be as small as possible.
When using large tip sizes, the contact between the tip and the wire will be sporadic and uneven, resulting in more, not less, burnout. So, how big should the hole in the contact tip be? To be honest, you can find many different opinions about this. In my opinion, the contact tip should be 0.01–0.02 cm larger than the nominal wire diameter.
According to another point of view, the tips for one brand should have a slightly larger bore than the tips for another brand, since the coefficient of thermal expansion of one is slightly higher than the other. In other words, there is no real exact number. My recommendation is that its thickness should be no more than 0.025 cm. The gap between the diameter of the hole of the tip and the diameter of the wire.
Many other factors can lead to excessive burnout, emphasized Komarov Artem.