MIG/MAG welding: This is how it works

In MIG/MAG welding, the arc is created by a short circuit when the wire comes into contact with the component. After the short circuit, the arc ignites and the melting wire serves as filler material.

To protect the arc and the molten pool from the reactive oxygen in the environment, shielding gas flows from the gas nozzle. It covers the welding area and, above all, prevents oxidation of the liquid metal - i.e., the weld droplets and the molten pool. 

This is how a MIG/MAG welding system is structured:

(1) Mains connection

(2) Power source

(3) Hosepack

(4) Grounding cable

(5) Welding torch

(6) Ground terminal

(7) Workpiece

(8) Filler metal

(9) Shielding gas

Dip transfer arc

When the wire touches the workpiece, a short circuit occurs, the current increases, and the wire electrode liquefies, causing the arc to ignite. In a further short circuit, the molten wire is transferred to the molten pool. This recurring process enables safe root welding and the welding of thin sheets in almost any position.

Intermediate arc

The intermediate arc alternates irregularly between short-circuit and spray transfer in the power range. This typically leads to increased spatter formation. Nevertheless, this arc is suitable for position welding and for applications that require reliable penetration.

Spray arc

In the high power range, droplet transfer occurs without short-circuiting. The arc burns stably, delivers high melting power and high arc energy, and enables deep penetration. This makes it particularly suitable for welding thicker sheets.

Pulsed arc

The pulse arc combines a low-power base current phase with a high-power pulse current phase. In the base current phase, the arc burns steadily and preheats the workpiece surface. In the pulse current phase, a precisely metered current pulse triggers a single weld drop. This precisely controls the material transfer, prevents unwanted short circuits, and reduces spatter formation.

Rotating arc

At very high welding currents, the arc can be set in rotation by magnetic force. This so-called high-performance arc transfers the droplet into the molten pool in a rotating motion. It achieves very high melting rates and is particularly suitable for welding thicker sheets and for applications involving gap bridging. 

Mix processes (combined arc)

Mix processes are characterized by the cyclical alternation between two types of arcs and combine their advantages in a targeted manner.

A common example is the combination of short arc and pulsed arc:
During the pulse phase, penetration and heat input are provided. During the short arc phase, the weld pool cools down and remains more controllable. Among other things, this combination enables safe vertical welding and uniform seam scaling—while maintaining high seam quality.