The Ultimate Guide To TIG Welding Settings

The Ultimate Guide to TIG Welding Settings

What TIG Welding Settings Control—and Why They Matter

Dialing in TIG welding settings is the difference between a flawless stack of dimes and a frustrating mess of porosity and distortion. TIG, or GTAW, gives you granular control over heat, arc shape, and cleaning action, so each parameter must be matched to the base metal and joint design. Core settings include polarity and current type (DC or AC), amperage and slope, pulse parameters, shielding gas flow, and tungsten geometry. Getting these right improves penetration, bead profile, and metallurgy, while minimizing rework and post-processing. This guide walks through practical, repeatable baselines and the “why” behind them so you can tune with intent, not guesswork.

Power Source Modes: DCEN, DCEP, and AC for Different Metals

On most inverter TIG machines, you’ll choose between DC and AC, and then set electrode negative (EN) or positive (EP) in DC. DCEN (Direct Current Electrode Negative) is the default for steels, stainless steels, nickel alloys, and titanium because it concentrates heat in the workpiece for deep, controlled penetration. DCEP (Direct Current Electrode Positive) is rarely used for welding but sometimes employed for quick oxide “spot cleaning” on aluminum; it overheats and balls the tungsten quickly. AC is the standard for aluminum and magnesium, alternating between EN for penetration and EP for oxide removal, with frequency and balance fine-tuning the arc.

• DCEN: Primary mode for carbon steel, stainless, and most reactive alloys; sharp or truncated tungsten point; argon shielding.
• DCEP: Very limited use; avoid for production welding due to tungsten overheating and shallow penetration.
• AC: Aluminum and magnesium; set AC balance for cleaning vs penetration and AC frequency for arc focus.

Amperage Control, Foot Pedal Technique, and Starting Current

Amperage is your heat input lever, and how you meter it matters as much as the maximum you set. Many welders use a foot pedal to ramp current up for tacking, then modulate during travel to maintain a stable puddle size. Start current, slope-in, and slope-out (crater fill) settings help prevent tungsten contamination at start and shrinkage cracking at the end. For bench work, a high-frequency start with 10–30% starting current often lights cleanly; on thin sections, shorter ramps reduce heat soak. On production fixtures, a torch switch with programmable upslope/downslope gives repeatability without a pedal.

Rule-of-Thumb Amperage by Material

For DCEN on steel and stainless, a common baseline is about 1 amp per 0.001 inch of thickness (40 A for 1 mm, 100 A for 0.100 in), then adjust for joint fit and heat sinking. Aluminum on AC typically needs more current—about 1.5 amps per 0.001 inch—because heat is lost to oxide disruption and higher thermal conductivity. Match tungsten diameter to peak current to avoid tip overheating: 1/16 in (1.6 mm) to ~90 A DC or ~70 A AC, 3/32 in (2.4 mm) to ~150–200 A, and 1/8 in (3.2 mm) beyond that. Always set machine max amperage a bit above expected need so the pedal has “headroom,” then weld by puddle size, not by numbers alone.

Stainless steel: baseline settings

For 304/316 and the other austenitic grades, run DCEN with straight argon and a low-carbon filler matched to the base — ER308L for 304, ER316L for 316, ER309L for stainless-to-carbon or an unknown grade. Start near 1 amp per 0.001 in of thickness and expect to trim the pedal down as the part heats: stainless has about a third of mild steel’s thermal conductivity, so it stores heat locally and keeps climbing through a bead. Use a 2% lanthanated tungsten sized to the current with a long, lightly truncated point, a gas lens with a #8–#12 cup at roughly 12–20 CFH, and a post-flow around one second per ten amps so the weld and tungsten stay shielded while they cool below oxidizing temperature. Keep interpass temperature under about 300°F (150°C) to avoid sensitization, and add pulse at 1–2 PPS on thin sheet to hold heat tint and distortion down. Where the root is hidden and fully penetrated, back purge it. For the technique and shop workflow that go with these numbers, see TIG welding stainless steel like a pro.

Starting and Crater Fill Settings

Set start current just high enough to establish a puddle quickly without blasting the joint—typically 10–25% of max for thin sheet and 20–40% for thicker plate. Use 0.2–0.7 seconds of upslope to avoid a cold-lap start on small parts; extend upslope for heavy fixtures. For crater fill, program 0.5–2 seconds of downslope with a final current of 5–15 A to taper out smoothly and prevent crater cracking, especially on aluminum and stainless.

Shielding Gas, Cups, and Flow Rates

Pure argon is the standard shielding gas for most TIG work, delivering a smooth, stable arc and clean bead appearance. Flow rate depends on cup size, gas lens use, joint geometry, and draft conditions, not just a single magic number. As a starting point: 10–15 CFH (5–7 L/min) with standard cups indoors, 15–20 CFH (7–10 L/min) with larger cups or mild drafts, and slightly less when using a gas lens. Overgassing can actually entrain air and cause porosity, so set for a calm, laminar shield—not a hurricane.

Choose cup size to match access and shielding needs: smaller for tight joints, larger for better coverage over wide fillets or reactive metals. A gas lens straightens the flow, allowing longer tungsten stick-out and better gas efficiency—especially helpful on fillets and inside corners. For stainless and titanium, use trailing shields or back purging on closed joints to protect the root and minimize oxidation or sugaring. Keep hoses short and leak-free; any hiss or excessive needle bounce on the flowmeter hints at a leak or restriction.

• Baselines: #6–#8 cup with 10–15 CFH for general work; #12 cup with lens at 15–20 CFH for wide fillets or outside corners.
• Draft control: Block cross-breezes; spot increases beyond 20 CFH often indicate poor cup choice or no lens.
• Purge: Stainless roots <10 ppm O2 for critical service; taper purge flow to avoid turbulence and soot.

Tungsten Electrodes: Alloy, Diameter, and Tip Geometry

Tungsten choice affects arc starts, stability, and tip life. Modern inverters favor 2% lanthanated (blue) as a versatile option for both DC and AC, with good low-amp starts and minimal tip erosion. Ceriated (2% gray) is excellent for low-amperage precision on thin stainless and mild steels; thoriated (2% red) performs well on DC but is mildly radioactive and generally being phased out. Match diameter to current and pick a tip geometry suited to the mode: sharp to truncated point for DCEN, and truncated point or small controlled ball for AC. Keep the grind marks lengthwise to the electrode to stabilize the arc and reduce wandering.

• Diameter guides: 1/16 in (1.6 mm) ~15–90 A DC, 20–70 A AC; 3/32 in (2.4 mm) ~70–200 A DC, 90–180 A AC; 1/8 in (3.2 mm) 150–300 A+.
• DC tip: Sharpen to a long point (~2.5× diameter taper) or a truncated point with a tiny flat to resist tip nubbing.
• AC tip: Truncated point works well on inverters; avoid uncontrolled large balls that diffuse the arc and reduce penetration.
• Contamination: If the tungsten touches the puddle, stop, clip the contaminated end, and regrind—don’t weld through it.

AC Settings for Aluminum: Frequency, Balance, and Waveform

AC TIG introduces two powerful levers: frequency (Hz) and balance (%EN), plus waveform shapes on advanced machines. Frequency controls arc focus; 60–100 Hz gives a soft, wide arc for general plate, while 100–150 Hz tightens the arc for fillets and corners. Higher frequencies (above ~150 Hz) can improve directional control on thin edges but increase audible noise and may reduce puddle wetting if pushed too far. AC balance sets the percentage of time the electrode is negative (EN) for penetration versus positive (EP) for oxide cleaning; more EN boosts penetration and tungsten life, while more EP increases the etched zone and cleaning. Modern baselines often land around 65–75% EN for clean aluminum, adjusted by eye for the thinnest possible etched zone without black smut or oxide islands.

Waveform choice shapes how the current switches between EN and EP. Advanced square wave delivers crisp arc starts, strong penetration, and efficient oxide disruption; sine or soft square waves feel smoother but may broaden the puddle. If you see excessive etching or a fuzzy arc, try increasing EN a few points or dropping frequency slightly. Conversely, if the puddle won’t dig in, add a touch of EN or lower travel speed for better fusion. Always evaluate the etched zone: a narrow, even halo indicates correct balance; wide, frosty borders suggest too much EP or contaminated shielding.

• Starting points: 120 Hz, 70% EN, advanced square waveform for 1/8 in (3 mm) 6061 plate; adjust balance 5% at a time.
• Edge work: 140–160 Hz can help control arc wander on outside corners or thin flanges.
• Thick sections: Lower frequency (80–100 Hz) softens the arc for broader wetting on heavy fillets.

Pulse TIG Parameters: Peak, Background, PPS, and Duty Cycle

Pulse TIG modulates current between a higher “peak” and lower “background” level to control heat input and bead appearance. Used correctly, it reduces distortion, helps with uphill control, and sets a rhythm for filler addition. The key parameters are pulses per second (PPS), peak amperage, background amperage (as a fraction of peak), and peak time (duty cycle). Many machines also let you program upslope into peak and downslope into background for smoother transitions. Think of pulse as a metronome: peak forms and moves the puddle, background lets it cool and freeze, locking in toe lines.

When to Use Pulse

On thin stainless sheet, 1–2 PPS provides a comfortable cadence for consistent filler dips while limiting heat tint. For critical cosmetic beads on aluminum fillets, 30–50 PPS tightens ripple spacing and reduces wash-out. Micro work and autogenous welds may use 100–200+ PPS at modest amplitude changes to stiffen the arc without obvious ripple. Pulse is not a band-aid for poor fit-up; use it to refine already sound technique and settings.

Baseline Pulse Setup

As a general baseline, set peak amperage to the manual value you’d use without pulse (for example, 90 A on 0.060 in stainless). Choose 30–50% background (27–45 A in this case) and a 40–60% peak time. Start at 1–2 PPS to develop timing; if you need less heat input and tighter bead spacing, step up to 4–10 PPS. For cosmetic aluminum work, try 30 PPS, 35–45% background, and 50% peak time, then refine by puddle response and ripple clarity.

Technique, Travel Speed, Filler Selection, and Heat Input

Machine settings only work when technique supports them. Maintain a tight arc length—ideally 1–1.5× the tungsten diameter—to concentrate heat and prevent wandering. Keep a 10–15° torch push angle with most materials, and feed filler at the leading edge of the puddle to avoid chill lines. Travel speed should be just fast enough to preserve a small, consistent puddle without lagging toes; if the bead swells, either increase amperage briefly with the pedal or pick up speed. Use chill bars, tack strategically, and sequence welds to spread heat and minimize distortion on thin assemblies.

• Filler alloys: ER70S-2 for mild steel, ER308L/ER309L/ER316L to match stainless grades, ER4043 or ER5356 for aluminum (match to base and service conditions).
• Heat input: Reduce by using pulse, tighter arc, gas lens, faster travel, and intermittent pedal application; increase by reducing travel or slightly lengthening arc (with caution).
• Edge protection: For thin edges, start a touch hot to form a puddle quickly, then back off the pedal and increase travel to avoid burn-through.
• Cleanliness: Degrease and mechanically remove oxides before welding; aluminum requires stainless brushes dedicated to that alloy.

Troubleshooting TIG Welding Settings: Porosity, Undercut, and Warping

Even with sound technique, settings that are a bit off can produce recurring defects. Systematically adjust one variable at a time and watch how the puddle and bead respond. Most TIG problems trace back to shielding, amperage control, AC balance/frequency on aluminum, tungsten geometry, or poor fit-up. Keep a notebook of baselines for each alloy and thickness so you can return to known-good parameters quickly. Below are common issues with likely causes and targeted fixes.

• Porosity in bead: Likely shielding gas issue (flow too low/high, drafts, leaks) or contaminated base/filler. Fix by setting 10–15 CFH with a gas lens, blocking drafts, leak-checking lines, and cleaning with acetone and fresh abrasives.
• Arc wander: Often from blunt or contaminated tungsten, excessive stick-out, or magnetic arc blow on DC. Regrind lengthwise, switch to gas lens, shorten stick-out, and reposition ground clamp.
• Undercut at toes: Travel too fast, arc too long, or background current too low during pulse. Slow slightly, tighten the arc, and raise background to improve puddle support.
• Wide etched zone on aluminum: Too much EP (low %EN) or excessive AC frequency. Increase EN by 5–10% and/or drop frequency toward 100–120 Hz; confirm clean base metal.
• Lack of fusion: Amperage too low or moving too quickly. Increase peak current or dwell slightly longer at the toes before adding filler.
• Tungsten nubbing/balling on DC: Current exceeds tungsten capacity or contact with the puddle. Upsize tungsten, reduce amperage, and ensure a truncated point with a small flat.
• Distortion/warping: Excess heat input from slow travel or high amperage. Use stitch welding or pulse, add chill bars and tacks, and sequence welds to balance shrinkage.