Abstract
Sincee a phenomena in wire feeding, when the arc current passed through a semi-automatic wire feed system had been previously reported, in this report, the several experiments in connection with electric phenomena in the contact-tip had been conducted. The results were as follows. The contact point exists at the top of the contact-tip. The contact voltage drop between the wire and contact-tip is about 1 volt. Usually, the wire touches the contact-tip and the current doesn't create sparks. But, it is fact that sometimes the wire doesn't touch the inner surface of the contact-tip in limited conditions. On the wire surface, various patterns can beobserved, for example, rough surface, melting spot etc. It was assumed that these surface patterns are made by electric joule heat passing from wire to contact-tip.
