Welding Processes Power Supply, part 4
There are many welding processes that apply power supply and which are presented in this article. One of the most popular welding processes that commercial welders perform these days and which had great usage in the past decades is the arc spot welding. The advantage of this type of welding is the ability of the commercial welder to spot weld from one side of the work. Moreover, this is a very fast welding method for the production of multiple spot welds with a high degree of reproducibility.
MIG welders know that the arc spot welding can be done by using gas shielded metal arc processes and tungsten inert gas. When the multiprocess welder performs tungsten spot welding, one uses the same power supply that is required when performing regular TIG welding process. In this case however, the commercial welder requires special spot welding gun and controls. During the TIG spot welding there is a fusion of the parent metal and no filler wire is used. As a rule, the commercial welder performs TIG spot welding on cold rolled and on stainless steels.
The MIG spot welding is usually performed by the MIG welders with usage of high amperages. The welding equipment used at the Gas shielded metal arc spot welding have higher volts. As every arc welder knows that welding currents that have smaller diameter wires up to about 1/16 in. may reach 500 amp. The wires with 1/16 in. diameter and larger make for welding currents of up to 750 amp. Similar to the TIG spot welding, special control is needed here as well through a special wire drive and control unit.
Plasma cutters also perform plasma arc welding, which is based on the plasma cutting technique and is similar to the tungsten inert gas process. This welding type has fewer limitations and is cheaper in price. The plasma welding is a fusion process with possible usage of cold filler wire. The electrode in this process is tungsten coated and water cooled because of the high temperatures used. The plasma here can be focused and result in a deep penetration on the weld.