Welding machines or welders are among the most essential tools for a welding professional. Welding machines generate heat that melts metal parts, so that these parts can be joined. However, there is no single welding machine that is suitable for all welding projects.
In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that, based on weld configuration (butt, full penetration, fillet, etc.), can be stronger than the base material (parent metal). Pressure may also be used in conjunction with heat or by itself to produce a weld. Welding also requires a form of shield to protect the filler metals or melted metals from being contaminated or oxidized.