Technical Foundation
What Is a TIG Welder?
TIG (Tungsten Inert Gas / GTAW) welding uses a non-consumable tungsten electrode and a shielding gas (typically argon) to produce a precise, clean arc, with filler metal added separately by hand — it's the process of choice for high-quality welds on thin material and where weld appearance and control matter most. The critical machine spec is AC vs. DC output: DC output is used for steel and stainless steel, while AC output (which cycles polarity) is required for aluminum and magnesium, since AC's cleaning action breaks up the oxide layer that DC alone can't penetrate.
Amperage range and duty cycle determine what material thickness the machine can weld and for how long before it must cool down — duty cycle is quoted at a specific amperage (e.g. 60% at 150A) and drops as amperage increases toward the machine's maximum. Input power (120V, 240V single-phase, or 3-phase) constrains where the machine can be used, and features like high-frequency arc start (versus scratch start), pulse capability and foot pedal amperage control affect weld quality and control on precision or aesthetic work.
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| Spec | What It Means | Why It Matters |
|---|---|---|
| AC/DC Capability | DC-only vs. AC/DC output | AC is required for aluminum/magnesium; DC-only machines cannot weld these materials |
| Amperage Range | e.g. 5-200A output range | Sets minimum thickness controllability and maximum material thickness weldable |
| Duty Cycle | % on-time at a rated amperage, e.g. 60% at 150A | Determines how long the machine can weld continuously before overheating |
| Input Power | 120V, 240V single-phase, 3-phase | Constrains where the machine can be plugged in and used |
| Arc Start Method | High-frequency start vs. scratch/lift start | HF start avoids tungsten contamination and arc strikes on the workpiece |
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Applications
Where TIG Welders Get Used
TIG welders are specified wherever weld precision, appearance and control matter most, especially on thin material, aluminum, or applications with strict weld-quality requirements.
Aerospace & Precision Fabrication
AC/DC TIG welders with pulse control specified for critical welds on thin aluminum and stainless aircraft components.
Food & Beverage Equipment Fabrication
DC TIG welding of stainless steel tanks, piping and equipment requiring clean, sanitary weld finishes.
Automotive & Motorsport Fabrication
AC/DC TIG welders for aluminum chassis, exhaust and body fabrication requiring precise heat control.
Sculpture, Art & Custom Fabrication
TIG welders valued for their control and weld appearance on visible, finish-critical metalwork.
Piping & Pressure Vessel Fabrication
DC TIG used for root passes on pipe welds requiring code-compliant, X-ray-quality weld integrity.
General Metal Fabrication Shops
Multi-process welders with TIG capability added alongside MIG and stick for shops needing process flexibility.
FAQ
TIG Welders Questions, Answered
Do I need an AC/DC TIG welder or is DC-only enough?
It depends entirely on the materials you're welding — DC-only TIG welders work well for steel, stainless steel, titanium and most other common metals, but they cannot properly weld aluminum or magnesium because DC alone can't break up the tenacious oxide layer on those metals. If aluminum welding is needed now or in the future, an AC/DC machine is required; if you'll only ever weld steel and stainless, a DC-only machine is more cost-effective.
What does duty cycle actually mean, and why does it matter?
Duty cycle is the percentage of a 10-minute period a welder can operate continuously at a given amperage before it needs to cool down — for example, 60% duty cycle at 150A means 6 minutes of welding followed by 4 minutes of rest. Duty cycle drops as you increase amperage toward the machine's rated maximum, so a machine that seems to have enough peak amperage for a job may still be undersized if it can't sustain that output long enough for continuous production welding.
What's the difference between high-frequency start and scratch/lift start?
High-frequency (HF) start ignites the arc without touching the tungsten to the workpiece, using a high-voltage spark, which keeps the tungsten tip cleaner and avoids contaminating or arc-striking the base metal — the standard for quality TIG work. Scratch or lift start requires briefly touching the tungsten to the work to start the arc, which is simpler and cheaper but can contaminate the tungsten tip and mark the workpiece, so it's found mainly on entry-level machines.
Why would I need pulse capability on a TIG welder?
Pulse TIG alternates between a high peak current and a lower background current at an adjustable frequency, which reduces overall heat input into thin material (reducing warping and burn-through), improves control on out-of-position welds, and can produce a more uniform, visually consistent weld ripple pattern — valuable on thin-gauge aluminum, stainless sheet, and aesthetic or aerospace-grade welding where both heat control and appearance matter.
Can a 120V TIG welder handle real production work, or is it just for hobbyists?
120V TIG welders are genuinely useful for thin-gauge material (typically up to roughly 1/8 in. depending on the machine and metal), light fabrication, and repair work, and modern inverter-based 120V units are capable of good quality welds within their amperage range — but they max out at a lower amperage than 240V or 3-phase machines, which limits them on thicker material or high-volume production. Match the machine's input power and amperage range to your actual material thickness and duty requirements, not just budget or portability.
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