Quick Answer: MIG welding (GMAW) uses an automatically fed wire electrode — faster, easier, and more cost-effective for thick metals and structural work. TIG welding (GTAW) uses a non-consumable tungsten electrode with a manually fed filler rod — delivering superior precision and cleaner welds on thin or exotic materials where quality is non-negotiable.
1. How Each Process Works
MIG Welding (GMAW — Gas Metal Arc Welding)
A continuous consumable wire electrode feeds automatically through a welding gun. The arc melts both wire and base metal simultaneously. An inert shielding gas — typically 75% argon / 25% CO₂ — blankets the weld pool to prevent oxidation. One hand operates the gun; settings are dialled in on the machine.
TIG Welding (GTAW — Gas Tungsten Arc Welding)
A non-consumable tungsten electrode generates the arc. The welder manually feeds a separate filler rod into the molten pool with the other hand, while a foot pedal controls amperage in real time. Pure argon is the standard shielding gas. The result: exceptional control over heat input, bead shape, and penetration. The key mechanical difference is how filler metal enters the weld pool: automatically in MIG, manually in TIG. That single distinction drives most of the trade-offs in speed, skill, cost, and quality.
2. Side-by-Side Comparison
| Factor | MIG (GMAW) | TIG (GTAW) | Edge |
| Speed | High — continuous wire feed; long fast beads | Slow — manual filler feeding limits travel speed | MIG |
| Weld Quality | Good — minor spatter, occasional inconsistency | Excellent — no spatter, clean bead, minimal cleanup | TIG |
| Ease of Learning | Beginner-friendly; weeks to competence | Advanced; months to years to master | MIG |
| Material Thickness | Best on 3 mm and thicker steel | Best on thin sections (under 6 mm) | Situational |
| Metal Types | Steel, stainless, aluminum | Almost any: titanium, magnesium, copper, alloys | TIG |
| Weld Appearance | Functional; post-weld cleanup may be needed | Beautiful; stack-of-dimes bead, minimal grinding | TIG |
| Equipment Cost | $300–$1,500 CAD typical | $700–$3,000+ CAD typical | MIG |
| Labour Cost | Lower — faster throughput, lower cost per bead | Higher — slow process adds labour hours | MIG |
| Skill Required | Moderate — machine settings are the key skill | High — two-hand + foot pedal coordination required | MIG |
| Best Industries | Automotive, construction, structural, manufacturing | Aerospace, food service, medical, decorative | Situational |
3. MIG Welding — In Depth
How the Wire Feed Changes Everything
The automated wire feed is MIG’s defining advantage. Because the machine continuously delivers both electrode and filler metal, the welder focuses solely on torch angle, travel speed, and gun position — dramatically reducing mental load compared to TIG.
Where MIG Excels
MIG is the dominant choice for structural steel fabrication, automotive bodywork, farm equipment repair, heavy machinery, and construction. In Ontario shops, MIG handles the bulk of day-to-day production welding on carbon and stainless steel.
MIG Limitations
Inconsistent arc strength if settings are not properly calibrated can lead to porosity or burn-through on thin material (under 1.5 mm). Outdoors, wind disrupts the shielding gas envelope — which is why stick or flux-core welding is preferred for exposed site work.
Shielding Gas for MIG
The most common MIG blend in Ontario is C25 — 75% argon, 25% CO₂. CO₂ improves penetration and reduces porosity. Pure CO₂ is cheaper but produces more spatter. Tri-mix gases are used for stainless steel MIG to produce cleaner welds.
4. TIG Welding — In Depth
Precision as a Design Feature
The foot pedal amperage control is TIG’s secret weapon. A welder can modulate heat in real time — backing off at a tight corner to avoid burn-through, boosting at a gap to fill a cold joint. No other common arc process offers this level of dynamic heat control.
Where TIG Excels
TIG is the process of choice when the weld will be visible, load-critical on thin sections, or in contact with food or chemicals. Stainless steel kitchen equipment, aluminum bike frames, titanium aerospace brackets, decorative railings, and pipe welds requiring X-ray quality all call for TIG.
TIG on Aluminum
Aluminum TIG welding uses an AC (alternating current) arc, which provides a cleaning action that breaks up the hard aluminum oxide layer before each pass. This makes TIG the preferred process for aluminum in automotive, marine, and architectural fabrication — especially on thin sections.
Shielding Gas for TIG
TIG exclusively uses 100% argon for most metals. Adding CO₂ (as in MIG) would oxidize the tungsten electrode and contaminate the weld. Helium or argon/helium mixes are used for deeper penetration on thick copper or aluminum.
5. When to Choose Each Process
If a project ticks more boxes on one side of the table below, that is typically the right process.
| Choose MIG When… | Choose TIG When… |
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6. Cost Comparison
Equipment
A quality MIG welder for professional use costs $600–$2,000 CAD. An equivalent TIG machine runs $1,200–$4,000+. AC/DC TIG units for aluminum cost more still.
Consumables
MIG uses relatively inexpensive wire (~$15–$40/kg for ER70S-6) and standard contact tips. TIG uses tungsten electrodes (reusable but gradually consumed), argon gas, and separate filler rods — contributing to a higher cost-per-metre of finished weld.
Labour
Labour is usually the dominant cost factor. Because MIG deposits metal significantly faster, MIG labour costs per metre of weld are substantially lower. On a structural steel project this can be the deciding factor — TIG at that thickness offers no quality benefit over MIG.
7. Ontario & GTA Context
In Ontario, welders performing structural work must comply with CWB (Canadian Welding Bureau) certification standards. Mobile Welding Service operates with CWB-certified welders across Toronto, Mississauga, Brampton, Vaughan, Markham, Hamilton, and Burlington.
Ontario’s weather also influences process selection. Wind-exposed sites in the GTA make both MIG and TIG challenging without shielding. An experienced mobile welder will assess wind conditions and may use temporary shielding or switch to stick / flux-core for outdoor structural repairs.
For on-site work in the GTA, the most common scenario is MIG for structural and heavy repair, and TIG for stainless steel or aluminum in commercial kitchens, facilities, and custom fabrication. Our mobile units carry equipment for both processes.
Not Sure Which Process You Need?
Our CWB-certified mobile welders assess your project on-site and recommend the right process — MIG, TIG, or stick. Serving Toronto, Mississauga, Brampton, Vaughan, Hamilton, Burlington & all GTA.
Frequently Asked Questions
What is the main difference between MIG and TIG welding?
MIG (GMAW) automatically feeds a consumable wire electrode, making it fast and beginner-friendly. TIG (GTAW) uses a non-consumable tungsten electrode and requires the welder to hand-feed a separate filler rod — enabling far greater precision at the cost of speed and skill complexity.
Which is stronger — MIG or TIG welding?
Both processes can produce welds that match or exceed base-metal tensile strength. TIG is generally considered superior on thin materials due to precise arc control. Properly executed MIG welds on structural steel are equally strong — the construction and manufacturing industries rely on MIG for load-bearing work.
Which process is faster?
MIG is substantially faster. Continuous wire-feed allows long, uninterrupted beads at high deposition rates. TIG requires manually adjusting the filler rod after each dip, resulting in much lower deposition rates — acceptable for precision but impractical for high-volume production.
When should I use TIG instead of MIG?
Choose TIG for thin materials (under ¼ inch / 6 mm), exotic or reactive metals, food-grade equipment, visible decorative welds, aerospace applications, or any situation where weld appearance and zero contamination are critical. TIG is also specified for pipe root passes where X-ray quality is required.
Is MIG or TIG welding more expensive?
TIG costs more at every level: equipment (TIG machines run roughly double the cost of MIG), consumables (tungsten and filler rods cost more than wire), and labour (slower process means more hours per metre of weld). MIG is the cost-effective default for structural and production welding.
Can mobile welders do MIG and TIG on-site in Toronto and the GTA?
Yes. Mobile Welding Service carries both MIG and TIG equipment and serves all communities across Toronto, Mississauga, Brampton, Vaughan, Markham, Hamilton, Burlington, and surrounding GTA areas. Our CWB-certified welders assess each job and recommend the appropriate process before starting work.