Overview of the different welding processes

Inert gas welding (MIG) is an arc welding process in which a continuously fed welding wire acts as both electrode and filler material. An electric arc is formed between the wire and the workpiece, melting and joining the two materials. To protect the electric arc and the weld pool from atmospheric influences such as oxygen and moisture and thus prevent oxidation, argon or helium is usually used as the inert shielding gas.

A MIG welding system consists of several essential components: a power source that provides the welding current, a wire feed mechanism that continuously supplies the welding wire, a hose assembly with a welding torch that brings the wire and gas to the welding area, and a gas supply unit for supplying the shielding gas.

A wide variety of metals, especially non-ferrous metals such as aluminum and copper, can be welded with MIG welding, allowing for high welding speeds and clean welds with minimal rework. The process is also easy to automate and results in minimal welding distortion.

Since the shielding gas can be easily dispersed by the wind, which affects the welding quality, it has the disadvantage of being susceptible to wind and rust. For this reason, MIG welding is not suitable for outdoor use. It is also essential that the workpiece surface be clean, as impurities can affect the welding quality.

Metal-gas arc welding (MAG) is an arc welding process in which a continuously fed welding wire acts as the electrode and filler material. An electric arc is formed between the workpiece and the wire electrode, causing the two materials to melt and bond. The electric arc and the weld pool are surrounded by an active shielding gas, which is usually carbon dioxide (CO2) or mixed gases of argon with CO2 or oxygen. It protects them from atmospheric influences and has a targeted influence on the welding properties.

A MAG welding system consists of several main components: a power source that generates the welding current, a wire feed mechanism that continuously supplies the welding wire, a hose assembly with a welding torch that brings the wire and gas to the welding zone, and a gas supply unit for the shielding gas.

The versatility of MAG welding is one of its strengths, especially for processing steels with different alloys. It allows for high welding speeds and ensures reliable and strong welds, which can also have an attractive visual appearance. This process is extremely popular in industry due to its compatibility with different material thicknesses and its automation capability.

However, MAG welding can be affected by external factors such as wind, as the shielding gas can be dispersed, which has a negative effect on the quality of the welds. In addition, the surface of the workpiece must be carefully prepared, as contamination can have a negative effect on the welding results. These limitations make the process less suitable, especially for outdoor applications.

Tungsten inert gas (TIG) welding is a fusion welding process that uses a non-consumable tungsten electrode. An electric arc is formed between this electrode and the workpiece, melting the material. An inert shielding gas, usually argon or helium, surrounds the welding area and protects it from atmospheric influences such as oxygen and moisture to prevent oxidation and other chemical reactions.

A typical TIG welding system consists of a power source for the welding current, a hose assembly with a welding torch including the tungsten electrode and gas supply, a gas supply unit for the shielding gas, and a ground cable to form the electrical circuit. Manual addition of filler material is optional, especially for thicker materials or special applications.

TIG welding has the advantage of being able to weld almost any metallic material, including thin sheet metal and gas-sensitive metals such as titanium. This process produces high-quality, clean, spatter-free welds with high strength and good surface finish. TIG welding can also be used in any position and is well-suited to mechanized processes, such as orbital tube welding.

This process is less economical for thicker materials due to the relatively slow welding speed and higher energy consumption. In addition, TIG welding requires considerable skill and experience on the part of the welder, especially when manually feeding the filler metal. TIG welding equipment often requires a higher initial investment compared to other welding processes, and the process is less suitable for environments with dust or fumes.

Laser welding, a high-precision process, involves joining materials using a concentrated laser beam as a heat source. Over a small area, the laser beam generates a high energy density, resulting in local melting of the material and the formation of a weld bead. To protect the weld pool from oxidation and impurities, a shielding gas, usually argon or helium, is used.

Laser welding systems typically consist of a laser source (such as a CO₂ laser or a solid-state laser), a beam guidance system, focusing optics, a workpiece holder, and a gas supply unit for the shielding gas. These elements work together to precisely align the laser beam with the welding point and enable controlled welding.

Advantages of laser welding include, for example, high welding speeds, low thermal deformation of the workpiece, precise control of welding parameters, and the ability to join different materials. In addition, this process allows for deep, narrow welds with high strength.

The disadvantages include the high cost of purchasing laser systems and the need for special protective measures due to the intensity of the laser radiation. In addition, the process requires precise positioning of the workpieces and is sensitive to material reflections, which can affect the quality of the weld.

Gas welding, also known as autogenous welding, is a thermal welding process. In this case, the heat required to fuse materials is produced by the combustion of a fuel gas with oxygen. Acetylene is typically used as the fuel gas because, in combination with oxygen, it reaches a flame temperature of approximately 3,200 °C, sufficient to melt most metals. The welder has complete control over the welding process by manually guiding the resulting electric arc. This advantage makes the process particularly suitable for applications requiring precision.

A gas welding system consists of several main components: two gas cylinders (one for oxygen and one for fuel gas), regulators to regulate gas pressure, gas supply hoses, a welding torch to mix and ignite the gases, and anti-return devices to prevent flashbacks. In addition, different nozzle shapes can be used to adapt the flame focus to different parts and applications. This flexibility makes the process particularly popular for repair applications and thin sheet metal.

The advantages of gas welding include its mobility and versatility, since no power source is required. It is particularly suitable for repair work, for which the welding machine can be used independently of a power source. In addition to welding, brazing and cutting work can also be carried out, making this process indispensable in many workshops.

However, the disadvantages are the slow welding speed and the risk of thermal distortion (misalignment of the welding position) due to the high heat spread. Using a gas cylinder requires strict safety measures due to the risk of breakdown and explosion. In addition, operating costs are higher than with other processes due to higher gas consumption. The environmental impact of burning acetylene is also a disadvantage. Due to these factors, this process is not suitable for large industrial uses.