Loading …
Overview of the most commonly used welding processes and when they are used
Welding is one of the core competencies in the metal fabrication trade. Choosing the right welding method for the specific task is about both the material, material thickness, the requirements for strength and appearance, as well as whether the work takes place in the workshop or in the field.
On drawings and in welding procedures, the processes appear as numbers according to ISO 4063: 111 is manual metal arc welding with a covered electrode, 131 is MIG and 135 is MAG with solid wire, 141 is TIG with filler wire, and 311 is gas welding with oxygen and acetylene.
MIG (Metal Inert Gas) and MAG (Metal Active Gas) are both wire welding processes where an endless wire is fed through a welding torch and melts in the arc. The difference lies in the shielding gas: MIG uses an inert gas (typically argon or helium) and is mainly used for aluminium and stainless steel, while MAG uses an active gas (often CO2 or mixtures with argon) and is used for unalloyed and low-alloyed steel.
TIG (Tungsten Inert Gas) uses a non-consumable tungsten electrode and a separate filler rod, which the welder feeds into the weld pool with the other hand. The method produces very clean and controlled welds and is used where high demands are placed on quality and appearance — for example on stainless steel, aluminium and thinner materials.
With manual arc welding (also called stick welding or MMA) the arc burns between a coated electrode and the workpiece. The coating forms a protective slag and gas over the melt. The method is robust works well outdoors and in the field because it does not depend on shielding gas and is widely used for construction and repair work.
Gas welding uses a flame from fuel gas (typically acetylene) and oxygen to melt the material, often with an additive wire. Although the method has been superseded by electrical processes, the flame is still used for heating, bending, brazing and certain repair tasks.
The choice of method depends on material, material thickness, requirements for strength and finish, and the work site. A skilled metal fabricator knows the strengths and limitations of each method and combines them according to the task.