What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
A TIG welder (Tungsten Inert Gas welder, also called GTAW) is a machine that joins metal by creating an electric arc between a non-consumable tungsten electrode and your workpiece, shielded by argon gas — and it’s the right tool when you need clean, precise welds on thin steel, stainless, or aluminum. If you’re asking “whats a TIG welder” because you’re deciding whether to buy one, the short version is this: it produces the cleanest welds of any process but demands the most skill and runs the slowest. Here’s how to figure out if it fits your workshop.
As an Amazon Associate we earn from qualifying purchases at no extra cost to you.
What we cover
How a TIG Welder Actually Works
Unlike MIG or stick welding, nothing melts off the electrode — the tungsten stays intact and only carries the arc. You feed filler rod into the puddle by hand (or weld autogenously, fusing the base metal alone on thin material). A foot pedal or fingertip control adjusts amperage live while you weld, which is what gives TIG its famous precision on sheet metal, bicycle frames, and exhaust work.
The tradeoffs are real: most TIG machines weld at roughly half the speed of MIG, require both hands plus a foot, and have the steepest learning curve of any welding process. Plan on 20–40 hours of practice before your welds look consistent on steel, longer on aluminum.
AC vs. DC: The Decision That Shapes Everything
This is the single most important buying fork.
- DC-only machines weld steel, stainless steel, titanium, and chromoly beautifully, but cannot properly weld aluminum. They’re simpler and cheaper — typically $300–$800 for a capable unit.
- AC/DC machines add alternating current, which breaks up the oxide layer on aluminum while the electrode-negative portion of the cycle does the welding. If aluminum is ever in your plans, you need AC. Expect $800–$2,500 for a good inverter-based AC/DC machine.
Established names you’ll see in this space include Miller (the Diversion and Dynasty lines), Lincoln Electric (Square Wave TIG 200), ESAB, PrimeWeld, and Everlast. Budget imports under $400 exist, but check that pedal control and high-frequency arc start are actually included — many cheap units are lift-start only.
Matching Amperage and Features to Your Projects
A rough rule: you need about 1 amp per 0.001″ of steel thickness. That means a 200-amp machine handles material up to roughly 3/16″–1/4″ comfortably. Here’s how common shop situations map to specs:
| Project type | Material | Min. amperage | AC needed? | Typical machine budget |
|---|---|---|---|---|
| Sheet metal, auto body patch panels | Steel 0.030″–0.063″ | 100–130A, low-end control to ~5A | No | $400–$900 |
| Chromoly roll cages, bicycle frames | 4130 chromoly 0.035″–0.120″ | 150A | No | $500–$1,200 |
| Stainless exhaust, kitchen fab | 304/316 stainless | 150–180A | No | $600–$1,500 |
| Aluminum boat repair, intercooler piping | Aluminum 0.063″–0.250″ | 200A AC | Yes | $900–$2,200 |
| Heavy aluminum castings, thick plate | Aluminum 1/4″+ | 250A+ AC, water-cooled torch | Yes | $2,000+ |
Note the low end matters as much as the top: for auto body work, a machine that can start and hold a stable arc at 5–10 amps is more valuable than one rated at 250 amps that can’t run below 20.
Features Worth Paying For (and Ones That Aren’t)
- High-frequency (HF) start: Essential for aluminum, very nice for everything. Avoid scratch-start-only machines for TIG.
- Foot pedal: Non-negotiable for thin work. Fingertip controls on the torch are a budget alternative for one-position welding.
- Pulse: Genuinely useful — pulsing reduces heat input on thin material and helps beginners build timing. 1–2 pulses/second is the sweet spot for learning.
- AC balance and frequency control: On AC machines, adjustable balance (cleaning vs. penetration) and frequency (arc focus) matter on aluminum. Fixed-frequency budget machines work, just less flexibly.
- Duty cycle: Often ignored. A machine rated 60% at 150A means 6 minutes of welding per 10 at that amperage — fine for hobby work, limiting for production runs.
The Real Cost of Owning One
The machine is maybe 60% of your startup spend. A realistic first-year budget for a mid-range AC/DC setup:
| Item | Cost range | Notes |
|---|---|---|
| AC/DC TIG machine (200A class) | $900–$1,800 | Includes torch and pedal on most bundles |
| Argon cylinder, 80 cf, filled | $250–$400 | Refills ~$40–$70; budget 15–20 CFH flow rate |
| Consumables kit (tungstens, cups, collets) | $40–$80 | 2% lanthanated tungsten covers almost everything |
| Filler rods (ER70S-2, 308L, 4043/5356) | $60–$120 | Buy small quantities first |
| Auto-darkening helmet, gloves | $100–$300 | You likely own these already |
Worked example: an 80 cf cylinder at 15 CFH gives roughly 5.3 hours of arc time. At $55 per refill, that’s about $10/hour of gas — so a weekend fabricator burning 2 hours monthly spends ~$240/year on argon. Gas, tungsten, and filler together typically run $300–$400/year for hobby use.
Also check your power: most 200A machines run on 120V at reduced output but need a 240V circuit (often 30–50A) for full capacity. Dual-voltage inverter machines are worth the small premium if your shop wiring is uncertain.
What Wears Out and What Goes Wrong
- Tungsten contamination is the #1 beginner issue — dipping the electrode in the puddle or running insufficient post-flow gas (set 1 second of post-flow per 10 amps) grays the tip and destabilizes the arc.
- Torch consumables (cups, collets, gas lenses) are cheap and last months; back caps crack if the torch is dropped.
- Ground clamps and cables fail before the machine does on budget units — a poor ground causes arc wander that beginners blame on themselves.
- Dirty metal causes more bad welds than bad settings. Aluminum especially needs a dedicated stainless brush and acetone wipe.
FAQ
Can a TIG welder replace a MIG welder?
Not practically. TIG excels at precision and thin material; MIG is 2–3x faster on anything over 1/8″ and far easier to learn. Most serious shops run both — multi-process machines exist if you can only buy one unit.
Is lift-start TIG good enough?
For steel on a tight budget, yes. For aluminum or frequent start-stop work, high-frequency start is worth the upgrade — it avoids tungsten contamination on every arc initiation.
What thickness can a 200A TIG handle?
Single-pass: steel and stainless to about 1/4″, aluminum to about 3/16″. Thicker material is possible with beveling and multiple passes, but MIG is usually the better tool there.
The bottom line: if your projects involve thin steel, stainless, or any aluminum — and you value weld quality over speed — a 200A AC/DC TIG welder is the most capable single machine you can put in a small shop. If aluminum is never on your list, a DC-only unit saves real money.