MIG/MAG （Manual Metal MIG Welding）

Summary:

The wire electrode is fed by the wire feeder and conducts electric current through the contact tip to create an arc with the workpiece. It is positioned within the shielding gas nozzle, where the shielding gas flows out to protect the weld joint from atmospheric oxygen, hydrogen, and nitrogen.

Current type:

MIG/MAG gas shielded welding is performed using direct current (DC) with the electrode connected to the positive and the workpiece connected to the negative. However, there are some flux-cored wires that require the opposite polarity for welding. Recently, in certain very specific applications, such as MIG gas welding machine of extremely thin aluminum sheets, alternating current (AC) is also used.

Types of Welding Electrodes:

The flux coating on welding electrodes can be classified into different categories, and their compositions can vary significantly. The composition of the flux coating determines the melting characteristics, welding performance, and strength of the weld joint. For welding electrodes used with non-alloy steels, there are different types of flux coatings, including basic types and mixed types. The abbreviations used in the classification are derived from the corresponding English terms. Specifically, C stands for cellulose, A for acid, R for rutile, and B for basic. When it comes to welding electrodes for stainless steel, there are only two types available: rutile and basic.

The relationship between welding current (A) and electrode diameter can be estimated using the following empirical formulas: