A motor automatically unwinds a filler wire (2) from a reel and feeds it automatically towards the welding point. This wire is guided directly to the welding point by the contact sleeve (1).
Unlike tungsten inert gas welding (TIG) the filler wire melts. At the same time, shielding gas (3) is added through a nozzle, which protects the weld pool (4) against the effect of oxygen and therefore ensures oxidation-free joining of the metal parts (6). The finished weld is also called a weld run or bead (5).
For MAG welding (with active gases) a gas mixture of argon, carbon dioxide and oxygen is used. The proportions of the individual gases can be adjusted to the requirements of the material to be welded. In this way, secondary phenomena or side effects such as burn-in and spatter can be reduced. MAG welding is mainly used for unalloyed steels.
MAG Welding Specifications
Aluminium and aluminium alloys as well as low to high-alloy rustproof steels are materials which can be joined with MAG welding. In the case of higher alloy steels and aluminium, helium or argon can be used as the shielding gas, whereby argon is frequently used for cost reasons. The advantage of inert gases is that it is possible to weld with higher temperatures without the material oxidising. MAG welding can only be used indoors in enclosed rooms. Wind and weather could blow the shielding gas away and the welding process would take place without oxidation protection. This weld would then be of reduced quality, susceptible to rust and far less load-bearing.
This type of welding is frequently used to make vehicles, vessels and pipes as well as in mechanical engineering. Even in shipbuilding, it is difficult to image life without MAG welding. As, due to the fast welding speed, little deformation is to be expected, even in difficult or awkward positions, this arc welding procedure is primarily used for repairs and maintenance of thin metal sheets from 0.6mm thick. The weld is high-strength. Therefore almost no rework is necessary.
A differentiation is made between the following arcs:
- Short arc welding
Used for thin sheets as well as in difficult positions. A fine droplet, low sputter, i.e. smooth material transition is produced.
- Long arc welding
Used for thicker sheets and plates; A coarse droplet, spatter-intensive and non-short-circuit-free transition of the materials is produced.
- Spray arc welding
Used for thicker sheets and plates; By using argon-based mixed gases, large melting and higher speeds are achieved for welding thicker sheet and plate thicknesses. A fine droplet, very low spatter and short-circuit free material transition is produced.
- Pulsed arc welding
User for all sheet and plate thicknesses with mixed gases rich in argon. A pulsed current is supplied via the background current. The intensity of the droplets created during welding can be set, depending on the requirements. The results are a very uniform, fine droplet, very low spatter and practically short-circuit free material transition. Heat effects of the surrounding materials. This procedure can be used in all Welding positions. Due to these special advantages, it is now the most used welding procedure.
Advantages of MAG welding
The weld is protected against oxidation. No slag is produced. The working speed is very high. The result is lower heat effects of the surrounding material. This procedure can be used in all Welding positions. Due to these special advantages, it is now the most used welding procedure.
Wind susceptibility – metal shielding gas welding cannot take place outdoors. MAG welding requires a great deal of experience and is not easy to control. In addition, all rust must be removed from the weld area beforehand. Apart from proper protective clothing, particular attention must also be paid to strict use of eye protection in proper condition, as the weld flame develops a noticeably bright arc.