TIG arc starting problems usually come from tungsten condition, work clamp contact, gas coverage, torch setup, or start-mode settings before they come from a failed machine. If the arc will not start, starts only when scratched, wanders at ignition, snaps to the cup, or contaminates the tungsten immediately, check the tungsten point, work lead, cup/gas lens, collet grip, polarity, amperage start setting, and HF or lift-arc mode first.
The fastest check is to install a clean sharpened tungsten, clamp directly to clean bare metal, verify argon at the cup, remove drafts, and try a start on clean scrap. If the arc starts normally after those steps, the problem was setup or consumable condition, not the power source.
Related TIG checks include unstable TIG arc from poor tungsten prep, why TIG tungsten turns black, TIG porosity troubleshooting, and TIG cup size and gas coverage selection.
Common Symptoms
| Symptom | Likely Cause | First Check |
|---|---|---|
| Arc will not start with HF | Wrong mode, poor work lead, dirty tungsten, HF issue | Confirm HF start mode and clamp to clean metal |
| Arc starts only by touching | HF not active or work path too weak | Verify start mode, pedal/remote, and work clamp |
| Arc wanders at start | Poor tungsten grind, contaminated tungsten, long arc length | Regrind tungsten and shorten arc gap |
| Tungsten sticks on lift start | Too much pressure or wrong lift technique | Touch lightly and lift smoothly |
| Arc jumps to cup or side of tungsten | Loose collet, cracked cup, dirty gas lens, off-center tungsten | Inspect torch front end |
| Starts rough after every stop | Too little post-flow or contaminated tungsten | Check tungsten color and post-flow time |
Most Common Causes
- Contaminated tungsten: touching the filler, puddle, bench, or dirty base metal makes starts rough.
- Poor tungsten prep: uneven grind marks, blunt tips, split tips, and wrong taper make the arc wander.
- Weak work clamp path: paint, rust, mill scale, loose lugs, or clamping through a table can block a clean start.
- Wrong start mode: HF, lift-arc, scratch start, 2T/4T, pedal, or remote settings may not match the torch setup.
- Gas coverage failure: bad cup, clogged gas lens, loose back cap, low post-flow, or drafts oxidize the tungsten.
- Wrong tungsten size for amperage: oversized tungsten can be hard to start at very low amperage; undersized tungsten overheats.
- Dirty base metal: aluminum oxide, oil, rust, and coatings interfere with stable starts.
Inspection Steps
- Confirm process and polarity. Most DC TIG on steel/stainless uses DCEN. AC is used for aluminum and magnesium on AC-capable machines.
- Confirm start mode. Know whether the machine is set for HF start, lift-arc, or scratch start.
- Regrind tungsten. Use a clean dedicated wheel or tungsten grinder. Grind lengthwise, not around the electrode.
- Check tungsten size. Match electrode diameter to amperage range and machine start capability.
- Clamp directly to the work. Clean to bare metal and avoid relying on rusty tables, hinges, or fixtures.
- Inspect the torch front end. Check cup, gas lens, collet, collet body, back cap, O-ring, and tungsten centering.
- Verify argon at the cup. Flow at the regulator does not prove gas is reaching the tungsten.
- Check post-flow. If tungsten turns blue, gray, or black after the stop, it may start poorly next time.
- Try clean scrap. If the arc starts clean on scrap, the original part may be dirty, coated, oxidized, or poorly grounded.
HF Start vs Lift-Arc Checks
| Start Type | Problem | Fix |
|---|---|---|
| HF start | No arc unless touching | Confirm HF mode, remote settings, work clamp, and torch connection |
| HF start | Arc wanders before stabilizing | Regrind tungsten, shorten arc gap, clean base metal |
| Lift-arc | Tungsten sticks | Use lighter touch and smoother lift; clean tungsten and workpiece |
| Scratch start | Tungsten contamination | Use a copper strike plate or HF/lift start where procedure allows |
| Any mode | Hard restart | Increase post-flow, regrind tungsten, inspect gas leaks |
Field Fix vs Proper Fix
| Problem | Field Fix | Proper Fix |
|---|---|---|
| Dirty tungsten | Regrind point | Fix dipping, filler angle, gas coverage, and post-flow |
| Weak work path | Move clamp to clean metal | Repair cable, lug, clamp, or table return path |
| Arc wanders | Shorten arc length | Correct tungsten grind, size, and torch angle |
| Lift start sticks | Touch lighter | Confirm lift mode and clean contact point |
| HF start fails repeatedly | Try lift mode if available | Have HF circuit/service items checked by qualified repair |
Common Wrong-Part Mistakes
- Using a collet that does not match tungsten diameter.
- Installing a gas lens without the matching cup and insulator setup.
- Buying torch parts by welder model instead of torch series.
- Using oversized tungsten for low-amp work and blaming the machine for hard starts.
- Replacing the foot pedal before checking torch switch, remote setting, work clamp, and tungsten condition.
Compatibility Notes
TIG start behavior depends on welder start type, torch switch or pedal setup, tungsten size, torch family, collet size, gas lens or standard collet body, cup size, and work lead condition. WP-9/20-style consumables and WP-17/18/26-style consumables are not automatically interchangeable. Verify torch series and tungsten diameter before ordering consumables.
Related Failure Paths
- Black tungsten from low post-flow or gas leaks.
- Arc wander from poor tungsten preparation.
- Porosity from poor gas coverage during start and stop.
- Tungsten inclusion from scratch starting or sticking lift starts.
- Hard starts from poor work clamp contact.
- Unstable starts from dirty aluminum oxide or contaminated base metal.
Safety Notes
- Disconnect input power before servicing torch leads, work leads, or internal machine connections.
- Use eye protection when grinding tungsten.
- Follow shop rules for thoriated tungsten handling and dust control.
- High-frequency start can interfere with sensitive electronics; follow equipment and site requirements.
- Secure argon cylinders and use ventilation during test welds.
Sources Checked
- Weld Support Parts tungsten prep, tungsten discoloration, TIG porosity, and TIG cup support pages.
- CK Worldwide TIG guide and TIG troubleshooting guidance.
- Miller TIG welding basics and TIG problem troubleshooting guidance.
- Lincoln Electric high-frequency TIG start technology reference.
