upset but welding
Upset butt welding is a welding technique that produces coalescence simultaneously over the entire area of abutting surfaces or progressively along a joint, by the heat obtained from resistance to electric current through the area where those surfaces are in contact.
flash butt welding
The welding process used in joining mild steel shanks to high speed drills is Flash butt welding.
contact resistance
In arc welding, the electric arc is produced between the work and the electrode by Contact resistance.
work is connected to the positive terminal and electrode holder to the negative terminal
The welding set up is said to have straight polarity, when Work is connected to the positive terminal and the electrode holder to the negative terminal.
direct current is used
Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals when cool result in a binding of the metals.
For arc welding Direct current is used.