MIG and TIG are the two workhorses of the modern fabrication shop, and choosing between them is one of the more consequential decisions a welder makes. Both join metal with an electric arc under shielding gas, but they trade speed, control, and skill in very different proportions.
How they differ at the arc
MIG, or gas metal arc welding, feeds a continuous wire electrode that melts into the joint while shielding gas protects the pool. It is fast, forgiving, and easy to learn, which makes it the default for production and general fabrication. TIG, or gas tungsten arc welding, uses a non-consumable tungsten electrode and, usually, a separately fed filler rod. The welder controls heat with a foot pedal and adds filler by hand, giving extraordinary control at the cost of speed.
When MIG is the right call
For thicker steel, long runs, and high output, MIG wins. A skilled operator lays down clean, strong welds quickly, and a beginner can become productive in days rather than months. Structural work, trailers, frames, and general repair all lean toward MIG because throughput matters and the joints are rarely cosmetic.
When TIG earns its keep
TIG is the choice when appearance, precision, or thin material is involved. It welds aluminium and stainless beautifully, handles thin sheet without burning through, and produces the clean, stacked-dime beads seen on show-quality work. Aerospace, food-grade stainless, and fine repair work rely on it. The trade-off is speed and a steeper learning curve; TIG rewards patience and punishes haste.
Practical considerations
MIG equipment is generally simpler and gas consumption is straightforward. TIG demands more setup, cleaner base metal, and a steadier hand, but it generates almost no spatter and needs little cleanup. Material type matters too: aluminium is far easier on TIG or with a MIG spool gun, while mild steel is happy on either.
The honest answer for many shops is to own both. Use MIG when volume and thickness dominate, and reach for TIG when the joint must look perfect or the metal is thin or exotic. Matching the process to the job, rather than forcing every weld through one machine, produces stronger, cleaner results with less frustration.