Welding Processes Compared: MIG, MAG, TIG & More

MIG, MAG, TIG, and manual metal arc welding all produce a welded joint. They differ so much in seam quality, production speed, and cost structure, though, that the choice of process can decide whether an entire assembly succeeds. Specify a drawing as simply "welded," and that decision gets left to the manufacturer.

In brief: Welding processes differ mainly in how they generate heat and what shields the weld pool. MIG and MAG welding use an arc with a consumable wire electrode and a shielding gas. TIG welding uses a non-consumable tungsten electrode instead, and manual metal arc welding uses a coated stick electrode. Under DIN EN ISO 4063, every process carries its own number, for example 135 for MAG or 141 for TIG.

What Are Welding Processes, and Why Does the Choice Matter for Buyers?

Welding processes differ mainly in how they generate the heat needed for welding. They also differ in what protects the melt from the surrounding air: a shielding gas, a coated electrode, or a layer of flux powder. The choice of process largely determines seam quality, achievable wall thickness, and how well the process automates.

For buyers, this matters: the welding process, together with the material and the required volume, determines which manufacturer can even produce economically in the first place. If the drawing omits the specification, the manufacturer usually picks whatever process their workshop already has. That's not necessarily the process that's optimal for the assembly. This is especially true for Far East production, where different workshops often specialize in different processes. Switching manufacturers can therefore mean switching welding processes too.

What Is the Difference Between MIG and MAG Welding?

MIG and MAG welding both belong to gas-shielded welding with a consumable wire electrode. They differ in the gas used. MIG welding (metal inert gas welding, DIN EN ISO 4063 process 131) uses inert gases like argon or helium. These gases don't react with the melt. MAG welding (metal active gas welding, process 135) uses reactive gases or gas mixtures instead. These deliberately influence penetration and weld pool temperature.

In our sourcing projects, the distinction between MIG and MAG rarely gets kept clean on quotes from the Far East. The same equipment usually handles both variants on the shop floor anyway. For unalloyed and low-alloy steel, MAG is the more common process in Europe. MIG dominates instead for aluminum and other non-ferrous metals, as well as for stainless steel. An inert gas is needed in each case, to avoid unwanted changes to the melt.

What Is Tungsten Inert Gas Welding (TIG)?

This welding process is one of the most precise of the common processes. With TIG welding (tungsten inert gas welding, DIN EN ISO 4063 process 141 with filler material, 142 without), the arc burns between a non-consumable tungsten electrode and the workpiece. An inert shielding gas protects the melt throughout. Filler material, if needed, gets fed in separately, either by hand or by machine.

The process produces very clean, spatter-free seams and is therefore particularly suited to thin sheet metal, tubing, and visually demanding parts. The drawback is lower deposition rates compared with MIG/MAG, which usually makes TIG welding uneconomical for large-format series parts. For thin-walled stainless steel tubing, though, the quality advantage often outweighs the longer welding time. That's especially true in applications like food or medical technology.

What Is Manual Metal Arc Welding?

With manual metal arc welding, also known as MMA or stick welding, the arc burns between a coated, consumable stick electrode and the workpiece. The coating gives off gases and forms a slag as it melts, both of which protect the weld pool from oxidation. Under EN ISO 4063 this process carries the number 111. It is one of the oldest processes still in widespread use.

Its big advantage is independence from shielding gas cylinders. That makes the process well suited to construction-site and outdoor repair welding, where wind would otherwise blow away a gas shield. For high-volume series production, it's rarely the most economical choice, though, due to lower deposition rates and the need to change electrodes. In Far East manufacturing, this process shows up mainly in repairs and one-off parts, less often in series production.

What Is Submerged Arc Welding?

This welding process also uses an arc as its heat source, but hides it completely under a layer of granular flux. Submerged arc welding (DIN EN ISO 4063 process 121) makes neither the arc nor spatter visible, since the flux fully covers the weld point. The flux partially melts and forms a slag layer that further protects the seam from oxidation.

The process achieves very high deposition rates alongside high seam quality. It's limited to flat or slightly inclined welding positions, though. It pays off mainly on long, straight seams on thick-walled parts like beams or vessels. For short or heavily curved seams, the setup effort rarely pays off.

Which Welding Process Numbers Exist Under DIN EN ISO 4063?

The standard ISO 4063 assigns a unique number to every welding process. That number frequently shows up directly in the weld seam designation on the drawing.

Which Welding Process Fits Which Material and Volume?

Which process makes economic sense depends mainly on the material, sheet thickness, and required volume. For stainless steel and aluminum, MIG or TIG is usually the better fit, while unalloyed structural steel in high volumes points toward MAG.

In practice, manufacturers often combine several processes within a single assembly, for instance TIG for the visible outer seam and MAG for load-bearing inner seams. Anyone who doesn't specify the desired process in the requirements specification leaves that decision to the manufacturer.

How Does the Welding Process Affect Quality Inspection?

The chosen welding process directly influences which checks make sense during incoming goods inspection. TIG seams are usually easy to judge visually. MAG and submerged-arc seams on thick-walled parts, though, often require non-destructive testing like ultrasonic or X-ray inspection to catch internal defects. The inspection method itself should match the welding process chosen, rather than being fixed the same way across every assembly.

In our sourcing projects, we always have the welding process documented in the inspection report. It's not just the pass/fail result that gets recorded. When complaints come in, seam defects often only make sense once the process and the parameters used are known too. The final outcome alone rarely explains what went wrong.

Frequently Asked Questions About Welding Processes

Which Shielding Gas Does MIG Use, and Which Does MAG Use?

MIG welding uses an inert, unreactive shielding gas like argon or helium. MAG welding uses an active gas or a CO₂-based gas mixture instead. That gas choice also determines the fitting material. MIG suits aluminum and other non-ferrous metals as well as stainless steel, MAG suits unalloyed and low-alloy steel.

Which Welding Process Suits Stainless Steel?

TIG and MIG welding both suit stainless steel well. Both use an inert shielding gas that doesn't attack the chromium oxide layer that gives stainless steel its corrosion resistance. MAG welding is usually not the right choice for it.

What Does the Number Behind the Weld Seam on a Drawing Mean?

That number is the process number under DIN EN ISO 4063. It indicates which welding process should produce the seam, for example 135 for MAG welding or 141 for TIG welding with filler material.

Which Welding Process Is Cheapest for High Volumes?

For high volumes of unalloyed steel, MAG welding is usually the most economical thanks to its high deposition rate and good automation potential. For long, straight seams on thick-walled parts, submerged arc welding can be even cheaper.

Conclusion: The Right Welding Process Determines Quality and Cost

No welding process is inherently the best; each combines specific strengths around material, seam quality, and volume. Specifying the right process already in the requirements specification avoids later disputes over seam quality and rework. Leaving that decision to the manufacturer instead carries exactly that risk.

Line Up supports you in selecting the right welding process and in quality-checking welded assemblies from Far East production. 👉 Schedule a no-obligation consultation.