OPERATION AND APPLICATION
OperationMIG welding is usually carried out with a handheld gun as a semi-automatic process. The MIG process can be suited to a variety of job requirements by choosing the correct shielding gas, electrode (wire) size and welding parameters. Welding parameters include the voltage, travel speed, arc (stick-out) length and wire feed rate. The arc voltage and wire feed rate will determine the filler metal transfer method. This application combines the advantages of continuity, speed, comparative freedom from distortion and the reliability of automatic welding with the versatility and control of manual welding. The process is also suitable for mechanised set-ups, and its use in this respect is increasing. MIG welding can be carried out using solid of flux-cored wire, or a copper-coated solid wire electrode. The shielding gas or gas mixture may consist of the following:
• Carbon dioxide
• Argon and carbon dioxide mixtures
• Argon with oxygen or helium mixtures
Each gas or gas mixture has specific advantages and limitations. Other forms of MIG welding include using a flux-cored continuous electrode and carbon dioxide shielding gas, or using self-shielding flux-cored wire, requiring no shielding.
The purpose of the MIG Welding power source is to feed the welding zone with the welding material, by means of a special torch, and to maintain the electric arc that is struck between the piece to be welded and the consumable wire. Unlike M.M.A. and T.I.G power sources, where there is only one regulating parameter (welding current), on M.I.G.-M.A.G. power sources there are two regulating devices, one which regulates electric arc intensity (welding voltage), and another which regulates the rate of welding wire feed (welding current).