---
title: "TIG vs MIG Welding: Which Your Part Needs"
description: "TIG is slower and more controllable; MIG lays metal down fast. How thickness, material, cosmetics and volume decide which your part needs."
canonical: https://openspindle.com/blog/tig-vs-mig-welding
author: "Tom"
datePublished: 2026-09-06T00:00:00.000Z
dateModified: 2026-09-06T00:00:00.000Z
category: "Process & DFM"
---

# TIG vs MIG Welding

TIG feeds filler by hand into an arc from a non-consumable tungsten electrode, giving fine control over heat and bead placement. MIG feeds consumable wire continuously through the torch, laying metal down several times faster with far less operator input. Use TIG for thin material, for aluminum and stainless where appearance or cleanliness matters, and where distortion must be controlled. Use MIG for thicker steel, long weld runs, and production volume where speed drives price. On most parts thickness and visibility decide it.

## What each process does

TIG, properly gas tungsten arc welding, strikes an arc between a tungsten electrode and the part. The electrode is not consumed. If the joint needs filler, the welder feeds a rod into the puddle with the other hand while modulating current with a foot pedal or torch control. Two hands and a foot, all working the same puddle.

MIG, properly gas metal arc welding, runs a spool of wire through the torch and into the arc. The wire is both electrode and filler, fed continuously at a set rate. The welder controls travel speed and gun angle; the machine controls deposition. One hand, one trigger.

That difference in mechanism is the whole article. Everything below follows from a hand-fed puddle you can throttle versus a continuously fed one you cannot.

## How the two compare

| Factor | TIG | MIG |
| --- | --- | --- |
| Deposition speed | Slow. Hand-fed, one bead at a time | Fast. Continuous wire feed, often several times the travel speed |
| Heat input | Low and adjustable during the weld | Higher, and set before the weld |
| Distortion risk | Lower, and controllable | Higher on thin material |
| Thin material | Down to roughly 24 gauge in skilled hands | Struggles below about 18 gauge without burn-through |
| Thick material | Possible but slow; needs many passes | Preferred above about 1/4 inch |
| Bead appearance | Stacked, uniform, often left unfinished | Coarser, usually ground if it will be seen |
| Spatter | Essentially none | Some, and it needs cleanup |
| Aluminum | Excellent with AC and a clean joint | Workable with a spool gun or push-pull, less controllable |
| Operator skill | High. The bottleneck is the welder, not the machine | Moderate. Easier to reach an acceptable weld |
| Cost driver | Labor hours | Wire, gas and cycle time |

## Thickness decides more of these arguments than anything else

Below about 18 gauge, MIG becomes difficult. The wire feed delivers heat faster than thin sheet can shed it, and the result is burn-through, blown-out edges and warped panels. TIG lets the welder back the current off mid-bead and keep the puddle small, which is why thin stainless boxes, small brackets and tube frames in light wall are almost always TIG.

Above roughly a quarter inch, the argument inverts. Filling a groove in half-inch plate with hand-fed TIG is possible and slow, and slow is the cost. MIG fills it in fewer passes with less labor, and on structural steel nobody is looking at the bead anyway.

Between those two, thickness stops deciding and the other factors take over: what the metal is, whether the weld is visible, and how many you need.

## Material changes the answer, particularly aluminum

Steel is the easy case. Carbon steel welds well either way, and the choice comes down to thickness, cosmetics and volume.

Stainless is where heat control starts to matter for reasons beyond distortion. Too much heat, and chromium carbides precipitate at the grain boundaries in the heat-affected zone, which strips the local chromium that gives stainless its corrosion resistance. The zone next to a hot weld can then rust while the rest of the part does not. TIG's lower and more controllable heat input reduces that exposure, and it is one reason stainless assemblies for food, medical or marine service are usually specified TIG.

Aluminum is the sharpest split. It conducts heat away fast, oxidizes instantly, and the oxide melts far hotter than the metal underneath. TIG on AC breaks up that oxide layer during the weld and gives the control aluminum's narrow window needs. MIG can weld aluminum, but the soft wire needs a spool gun or a push-pull feeder to avoid birdnesting in the liner, and the process gives up much of the control that made TIG the default. If your part is aluminum and the weld matters, expect it to be quoted TIG.

## Cosmetics, and what a finished weld costs

A TIG bead is usually presentable as welded. The stacked-dime appearance people associate with good TIG is the visible record of a hand-fed puddle, and on a visible corner it can be left alone.

A MIG bead is rarely left alone on a cosmetic part. It is coarser, it carries spatter, and if the part will be seen it gets ground flush and blended, which is labor. That labor is the trap in comparing the two on speed. MIG lays the weld down faster, then a person spends time removing the evidence. On a part where every joint is visible, the finishing hours can erase the deposition advantage entirely.

So the real question is not which process welds faster. It is which process gets you to a finished, acceptable part in fewer total hours. On a hidden structural weldment that is usually MIG. On a visible stainless enclosure it is usually TIG, even though the arc time is longer.

## Volume, and where the crossover sits

At prototype and low volume, TIG's labor cost is spread across few parts and its flexibility is worth paying for. Fixturing is minimal, changes are easy, and a skilled welder can work from a drawing without dedicated tooling.

As volume rises, MIG's speed compounds and the fixturing investment starts to pay back. Once a weldment is repeating in the hundreds, shops will look at MIG, at fixtures that hold the distortion out, and at whether the joints can be redesigned so a faster process can reach them.

There is a third option worth knowing about at that point. Robotic MIG is common on repeating weldments, and it changes the economics again: consistent travel speed, consistent heat, and much less bead variation than a person can hold over a shift. It needs volume to justify programming and fixturing, but if your part is heading for production it is worth asking whether it should be designed for it now rather than re-engineered later.

## What to put on the drawing

Specifying the process by name is usually the wrong instinct. Shops know which process suits the joint, and pinning them to one can price you out of a perfectly good alternative. What you should specify is the requirement the weld has to meet, and let the shop choose the process that meets it.

Say whether the weld is structural or cosmetic, and where. Say whether it must be continuous or whether stitch welds are acceptable, because continuous welding on thin sheet is an invitation to distortion and is often unnecessary. Give the weld symbol with size, and say which side. If the assembly has to hold a dimension after welding, say so and give the tolerance, because that is what tells the shop to fixture it, to sequence the welds, or to plan a straightening operation.

If the part is stainless and will live outdoors or in a wash-down environment, say that too. It tells the shop to control heat input and to passivate afterward, and it is the difference between a part that stays bright and one that shows rust at every joint in six months.

## A quick selector

| If your part is | Expect | Because |
| --- | --- | --- |
| Thin gauge sheet, under 18 ga | TIG | MIG heat input burns through and warps |
| Aluminum, any visible weld | TIG | Oxide layer and heat conduction need AC and fine control |
| Stainless for food, medical or marine | TIG | Lower heat input protects corrosion resistance at the joint |
| Visible architectural or consumer part | TIG | Bead is presentable as welded; no grinding hours |
| Structural steel weldment, hidden joints | MIG | Faster fill, appearance does not matter |
| Plate over 1/4 inch | MIG | Fewer passes, far less labor per joint |
| Repeating production weldment | MIG, possibly robotic | Speed and consistency compound with volume |
| A frame that must hold a dimension | Either, with fixturing | Sequence and fixturing matter more than the process choice |

## Related reading

- [Welding capabilities](https://openspindle.com/capabilities/welding.md)
- [Sheet metal fabrication](https://openspindle.com/capabilities/sheet-metal-fabrication.md)
- [Stainless steel properties](https://openspindle.com/materials/stainless-steel.md)
- [Aluminum properties](https://openspindle.com/materials/aluminum.md)
- [Sheet metal gauge chart](https://openspindle.com/reference/sheet-metal-gauge-chart.md)
- [Sheet metal bend radius chart](https://openspindle.com/reference/sheet-metal-bend-radius-chart.md)
- [Passivation spec](https://openspindle.com/reference/passivation-spec.md)
- [Stainless vs aluminum](https://openspindle.com/blog/stainless-vs-aluminum.md)

## Frequently asked questions

### Is TIG stronger than MIG?

No. A correctly executed weld in either process develops the strength of the joint design and the filler, and both can meet the same weld procedure specifications. TIG is often assumed to be stronger because it is cleaner and more controlled, which reduces the chance of defects like porosity or lack of fusion. The strength comes from the joint and the procedure, not from the process name.

### Why is TIG more expensive if the machines cost about the same?

Because you are buying hours, not equipment. TIG deposits metal far more slowly and demands a more skilled operator, so the same joint takes longer and the labor rate behind it is higher. On a visible part some of that is recovered, because a TIG bead often needs no grinding while a MIG bead does.

### Can aluminum be MIG welded?

Yes, with a spool gun or a push-pull feeder to stop the soft wire jamming in the liner. It is used on thicker aluminum and on production work where speed matters. For thin aluminum, or anywhere the weld will be seen, TIG remains the usual choice because aluminum's heat conduction and oxide layer leave a narrow window that hand control manages better.

### Should I specify the welding process on my drawing?

Usually not. Specify what the weld has to achieve: structural or cosmetic, continuous or stitch, the weld symbol and size, and any dimension the assembly must hold after welding. Shops choose the process that meets that. Naming a process can rule out an equally good approach and price the job higher than it needs to be.

### What causes a welded frame to come out of square?

Heat. Every weld shrinks as it cools and pulls the parts toward it, so an unfixtured frame welded in the wrong order will move. It is managed by fixturing, by sequencing welds to balance the pull from side to side, by stitch welding instead of running continuous beads where the joint allows, and sometimes by straightening afterward. Tell the shop which dimensions matter and it will plan for them.