The humans invented the first HF Welder torch to locally melt metal with focused heat. These torches made way for arc soldering, which gave even more intense heat. The TIG welder is one of the most versatile welding machines that can pinpoint heat even more, which allows for smaller, precision welds. Another popular type of soldering machine used today is the MIG welder.

Industries use Arc welding or stick welding in a number of applications which includes construction and repair work. This type uses a welding power supply with either direct or alternating current to create an electric arc between an electrode and the base material to melt metals at the fusing point. It's covered with flux to protect the weld area from oxidation and contamination. There are two types of arc welders which include air or oil cooled AC welders or DC welders that use an air cooling system. Arc welding is only limited to soldering ferrous metals.

MIG or metal inert gas soldering is a semi-automatic or automatic arc welding process that is also known as gas metal arc welding (GMAW). The process features a continuous and consumable wire electrode and shielding gas, fed through a MIG torch or the CO2 fusing gun. A direct current power source is usually used with a MIG welder, although alternating current is the second choice. One of the benefits of these soldering machines is that the voltage, amperage and the speed is adjustable. These machines also feature a variety tension and valve to control the flow of gas. A MIG welder used without shielding gas in a process is known as flux core arc welding. In this process the welding wire has a core filled with flux and has a hotter arc capable of welding thicker pieces of metal. A MIG welder used to weld copper, zinc, brass, steel, tin and aluminum. These machines are versatile and easy to learn, and is the ideal choice if you want to work on a variety of metals by purchasing only one welder.

Maintenance of an arc when welding with an ac power source is rather a problem because the arc extinguishes every half cycle when the current is zero, that is, it will extinguish 100 times a second with a normal 50 hertz mains supply. For re-ignition the required voltage must be available at the time the current is zero. This is achieved in ac welding by keeping the current and voltage waves out of phase by using a power source with a low operating power factor of about 0.3.

For these conditions, almost the full OCV is available to re-ignite the arc while the current is zero. The operating power factor of a power source can be improved while maintaining the ease of re-ignition only by using auxiliary means of maintaining or re-igniting the arc, for example, a high frequency high voltage spark gap oscillator can be used to supply a high voltage pulse at the appropriate instance. If such a technique is used to maintain the arc, then the power factor of normally adopted for gas tungsten arc welding using an ac welding power source. The situation can be further improved by using thoriated electrode with better electron emitting property.

Similarly, in arc welding machine (shielded metal arc welding) the electrode coatings with lower ionisation potential help in easy re-ignition of the welding arc.

In RF Welding Machine the arc maintenance is rather easy and it is only at the time of short-circuit between the electrode and the workpiece that the arc is extinguished. However, this problem is solved by providing suitable dynamic volt-ampere characteristics of the power source. Here again electrode coatings with low ionisation potential or with better emissivity can help in easy initiation and maintenance of the welding arc.