Tig Welding Guns

A1: Air-cooled guns are lightweight (0.5-1kg) and portable, suitable for low-current (≤200A), short-duration welding (e.g., repair work). Water-cooled guns are heavier (1.5-3kg) but handle high current (≥200A) and continuous welding (e.g., industrial production). Choose based on current needs: if you weld ≤3mm aluminum or steel occasionally, air-cooled suffices; for thick materials or daily heavy use, water-cooled is better.

A2: For aluminum (AC welding), use pure tungsten (EWP) or zirconiated tungsten (EWZr) for stable arc. For stainless steel (DC welding), use thoriated tungsten (EWTh-2) for high current capacity or ceriated tungsten (EWCe-2) for low current precision. Electrode diameter matches material thickness: 1.6mm for ≤1mm metal, 2.4mm for 1-3mm, 3.2mm for ≥3mm.

A3: Common causes: ① Poor tungsten electrode contact (tighten the electrode collet). ② Low shielding gas flow (check for leaks; increase to 10-15L/min). ③ Contaminated electrode (grind a new tip—avoid touching the weld pool with the electrode). ④ Incorrect polarity (DCEN for steel, AC for aluminum).

A4: After each use, remove spatter with a brass brush (avoid steel brushes, which scratch the nozzle). If spatter is stuck, heat the nozzle slightly to loosen it, then wipe with a cloth. Replace the nozzle if it’s cracked (leaks gas) or worn (irregular gas flow). Apply anti-spatter spray before welding to reduce buildup.

A5: Yes, but adjust settings and accessories: ① For steel/ stainless steel: Use DCEN (direct current electrode negative) and argon shielding gas. ② For aluminum/ copper: Use AC (aluminum) or DCEN (copper) with argon (aluminum) or argon-helium mix (copper, for deeper penetration). Always match the electrode to the metal (e.g., ceriated for steel, zirconiated for aluminum).

A6: Contamination occurs when the electrode touches the weld pool (melts metal onto the tip) or is exposed to oil/rust on the base material. To avoid: ① Keep a 1-3mm gap between the electrode and workpiece. ② Clean the base material with acetone or a wire brush. ③ If contaminated, grind the tip to remove impurities—use a dedicated tungsten grinder for a smooth, tapered end.

A7: Too low: Weld turns gray/porous (oxidation). Too high: Turbulence pulls in air (porosity). For 6-8mm nozzles (small workpieces), 8-12L/min. For 10-12mm nozzles (larger areas), 12-18L/min. For high winds (outdoor welding), increase by 5-10L/min and use a wind screen.

A8: ① Use AC current (breaks aluminum oxide layer). ② Clean the aluminum surface with a stainless steel brush (oxide prevents fusion). ③ Preheat thick aluminum (100-200℃) to avoid cold cracks. ④ Use a larger gas nozzle (10mm) for better coverage—aluminum oxidizes quickly.

A9: ① Check travel speed—too fast causes narrow, uneven beads; too slow leads to burn-through. ② Ensure steady gun movement (use a guide or practice hand stability). ③ Adjust current: Low current creates weak, narrow beads; high current causes irregular melting. ④ Keep the gun angle consistent (15-20° from the workpiece).

A10: A gas lens replaces the standard collet body with a porous metal filter, creating a laminar gas flow that extends farther from the nozzle. This improves shielding on irregular shapes (e.g., corners) and allows longer electrode stick-out (useful for hard-to-reach areas). It’s essential for aluminum and stainless steel welding.

A11: No. Without inert gas (argon/helium), the weld pool reacts with oxygen/nitrogen in the air, forming brittle oxides and porosity—ruining weld strength. Even “no-gas” TIG is a myth; some processes use flux, but that’s not true TIG. Always ensure gas flow before striking an arc.

A12: ① Use a larger diameter electrode (e.g., 3.2mm instead of 2.4mm for 250A). ② Choose a heat-resistant electrode (thoriated for DC, zirconiated for AC). ③ Reduce current if possible, or use a water-cooled gun to dissipate heat. ④ Avoid long arc length (keep it ≤ electrode diameter to reduce heat on the electrode).

A13: Undercut (grooves along weld edges) is caused by: ① Too high current (melts base metal faster than filler metal can fill). ② Travel speed too fast (insufficient filler). ③ Gun angle too steep (directs heat to edges). Fixes: Lower current by 10%, slow travel speed, or adjust angle to 10-15°.

A14: ① Use deionized or distilled water (tap water causes mineral buildup). ② Add 5-10% coolant additive to prevent corrosion and freezing. ③ Flush the system monthly (run clean water through for 5 minutes). ④ Check hoses for kinks/leaks—replace if swollen or cracked. ⑤ Drain water if storing in cold environments.

A15: Yes, but use a specialized orbital TIG gun (e.g., Swagelok orbital gun) with a rotating nozzle. These guns are mounted on a track around the pipe, ensuring consistent speed and angle—critical for pressure pipes (e.g., oil/gas lines). They require programming for weld parameters but produce uniform, code-compliant welds.

A16: Small nozzles (6-8mm): Offer better visibility for tight spaces (e.g., corner welds) but require precise gas flow (10-12L/min). Large nozzles (10-12mm): Provide broader gas coverage for large workpieces or high winds (flow 12-18L/min) but reduce visibility. Match to workpiece size—nozzle diameter should be 2-3x electrode diameter.

A17: Oil, rust, or paint on the base material causes porosity and poor fusion. Clean with: ① Acetone (removes oil). ② Stainless steel brush (removes rust/oxide—use a new brush for aluminum to avoid cross-contamination). ③ Sandpaper (for thick oxide layers on aluminum). Wipe clean with a lint-free cloth before welding.

A18: Uneven flow (causes erratic shielding) may stem from: ① A cracked gas hose (replace). ② A clogged gas filter in the gun (clean or replace). ③ A loose nozzle (tighten it). ④ Debris in the gas lens (disassemble and clean with compressed air). Test by holding the nozzle 5mm from a soap film—bubbles should be uniform.

A19: 2% thoriated (EWTh-2) has higher current capacity and longer life, ideal for DC welding of steel (200-300A). It’s radioactive (low level) but widely used in industry. 2% ceriated (EWCe-2) works well at low current (≤150A), is non-radioactive, and starts arcs easily—better for precision work (e.g., electronics) or AC aluminum welding.

A20: ① Clean the gun: Remove spatter, wipe with a dry cloth, and store in a case. ② For air-cooled guns: Hang vertically to avoid bending the cable. ③ For water-cooled guns: Drain coolant, blow air through hoses to dry, and disconnect from the water supply. ④ Keep electrodes in a sealed container to avoid moisture/rust. ⑤ Store in a dry, cool place (avoid direct sunlight).

A21: Trigger issues (no arc start, stuck trigger) are often due to: ① Dirt in the trigger mechanism (disassemble and clean with compressed air). ② A broken spring (replace with a manufacturer-approved part). ③ Damaged wires (check for cuts in the cable—repair with heat-shrink tubing). Avoid pulling the trigger sharply to extend its life.

A22: Yes, but it’s challenging. Use a filler metal compatible with both (e.g., ER4043 aluminum-silicon alloy) and a DC TIG gun with high-frequency start. Preheat aluminum to 150-200℃ (steel needs no preheat) and keep the arc on the aluminum side (it conducts heat poorly). Weld in short bursts to avoid brittle intermetallic compounds.

A23: AC balance controls the ratio of “electrode positive” (EP) to “electrode negative” (EN) cycles. EP cleans the oxide layer (essential for aluminum), while EN provides penetration. For thin aluminum (≤2mm), use 70-80% EP (more cleaning). For thick aluminum (≥3mm), use 50-60% EP (more penetration). Test on scrap to find the sweet spot—too much EP causes spatter; too little EN causes poor fusion.

A24: ① Auto-darkening helmet (shade 10-12 for TIG) to block arc UV/IR radiation. ② Leather gloves (heat-resistant, gauntlet-style to protect wrists from spatter). ③ Flame-retardant jacket (cotton or leather—avoid synthetic fabrics that melt). ④ Respirator (if welding in confined spaces, to filter fumes from aluminum or stainless steel). ⑤ Safety glasses under the helmet (for lens changes).

A25: Porosity (tiny holes) is caused by: ① Contaminated base metal (reclean). ② Low gas flow or leaks (check connections with soapy water). ③ Moisture in the gas (drain the gas cylinder or replace the filter). ④ Filler metal with oil (wipe with acetone). If porosity persists, increase gas flow by 2-3L/min or switch to a larger nozzle.

A26: With a single pass: Air-cooled guns handle ≤3mm steel/aluminum; water-cooled guns handle ≤6mm. For thicker materials (6-20mm), use multi-pass welding: first pass (root) with low current, then fill passes with higher current. Preheat thick steel (150-300℃) to reduce cracking, and use a filler metal matching the base material.

A27: Foot pedals allow hands-free current control (ideal for continuous welding, e.g., long seams) and offer precise adjustment during the weld. Hand controls (integrated into the gun) are better for tight spaces (e.g., overhead welding) or when foot movement is restricted. Choose based on comfort—most professionals prefer foot pedals for fine control.

A28: Overheating cables (warm to the touch) are due to: ① Exceeding the cable’s current rating (e.g., 100A cable used for 200A). ② Cable kinks (restrict current flow, increasing resistance). ③ Poor connections at the gun or machine (tighten terminals). Replace with a heavier-gauge cable (e.g., 4AWG instead of 6AWG) for high-current use.

A29: Yes. TIG’s precise heat control makes it ideal for brazing (using filler metal with lower melting point than base metal). Use a low current (50-150A), argon gas, and brass filler (e.g., BCuP-5). Heat the base metal until the filler flows—avoid melting the base metal. Clean joints first to ensure adhesion.

A30: ① Check gas flow: Turn on gas, block the nozzle, and ensure the pressure gauge holds (no drop = no leaks). ② Test arc start: Strike an arc on scrap metal—should start smoothly with no sputter. ③ Inspect weld appearance: A good test weld has a uniform bead, no porosity, and solid fusion. ④ Check cooling: After 5 minutes of welding, the gun should be warm but not hot (air-cooled) or cool (water-cooled).