Guide
Types of welding: stick, MIG, TIG, plasma, oxy-fuel, laser, and which to choose
Six processes, each with its metal, its speed and its finish. Here is how they work and how a shop chooses the one for your part.
Updated
Stick welding (SMAW)
An electric arc melts the base metal and a coated electrode. The coating produces a slag that shields the weld pool, then chips off with a hammer.
It is the field process by definition: a compact machine, no gas, unaffected by wind. It welds thick, rusty or painted steel. The bead needs more finishing and the pace is slower.
MIG and MAG welding
A wire electrode feeds continuously and melts under the arc. A gas shields the pool: inert for MIG, active for MAG. Flux-cored wire does the same job without a gas bottle.
It is the shop’s production process. Fast and steady, it joins steel from 1 mm to several centimetres. It suits very thin or highly visible joints less well.
TIG welding
A tungsten electrode, which does not melt, creates the arc. The welder adds filler metal by hand, under argon. The bead is fine, clean, without spatter.
It is the process for visible joints, stainless, aluminum and thin sheet. It is slower than MIG and needs an experienced welder.
Plasma welding
An arc squeezed through a nozzle forms a plasma jet, hotter and narrower than a TIG arc. It penetrates deeply in one pass, with little distortion.
It is found in aerospace and precision piping. In a fabrication shop, plasma is mostly used to cut sheet, not to weld.
Oxy-fuel welding
An oxygen-acetylene flame heats the parts and a filler rod. No electricity is needed.
The process remains useful in plumbing, repair and brazing. For metal fabrication it has given way to the arc: slower, more heat spread, more distortion.
Laser welding
A concentrated beam melts the metal without contact. The bead is narrow, distortion minimal, the pace high.
This process equips electronics, medical and automotive plants, on thin, repetitive parts. It does not replace the arc for thick structures and one-off parts.
Which one for your part
| Situation | Usual process |
|---|---|
| Steel structure, chassis, bracket | MIG |
| Thick reinforcement, dirty or damp environment | Flux-cored or stick |
| Food-grade stainless, aluminum, visible joint | TIG |
| Field repair, outdoors | Stick |
| Thin sheet in high volume | Laser or pulsed MIG |
| Pressure piping, aerospace | TIG or plasma |
The process is chosen at the drawing, not at the station. Metal, thickness, welding position and expected finish decide before the first arc.
What PacoMetal uses
The shop welds with MIG, TIG, stick and flux-cored wire, in-house and on site with the mobile unit. Plasma is used to cut sheet. Laser welding is not offered.
On a single project the processes combine: MIG for the structure, TIG for the joints that show. That is what was done on the Mika Sushi Bar wine cellar and on the Bill Durnan arena railings.