Tig Welding
TIG welding, or Gas Tungsten Arc Welding (GTAW), is an arc-welding process using a non-consumable tungsten electrode and inert shielding gas, typically argon, to protect the weld pool from oxidation. It offers precise heat control, low spatter, and clean welds, especially on thin stainless steel, aluminum, magnesium, copper, and non-ferrous alloys.
In a CNC machining or millwork environment, TIG welding follows precision machining once parts have accurate fit-up, clean edge prep, and controlled joint geometry. The arc forms between tungsten and workpiece, while filler wire is added externally when the joint demands more cross-section than autogenous fusion provides. This gives direct command over bead size, penetration, and heat-affected zone shape, protecting dimensional accuracy on frames, brackets, stainless fixtures, coolant tanks, and process piping. Because TIG rewards tight gaps and clean surfaces, poor fit-up forces excess filler and distortion risk climbs. The process is integrated carefully with CNC equipment, since high-frequency start and arc noise can emit electromagnetic/radio-frequency interference that disrupts controllers, encoders, and breakout boards. Grounding, shielding, cable separation, and isolating electronics are standard countermeasures. Pre-weld cleaning of oxides, coatings, and contaminants is equally critical to avoid porosity, lack of fusion, unstable arc behavior, and contaminated tungsten.
Why is tungsten used instead of a consumable wire?
Tungsten has a high melting point and sustains the arc without becoming filler metal, so heat input and metal addition are controlled separately. That separation is what gives TIG its precision on thin and non-ferrous workpieces.
When is filler metal necessary?
Filler is added when the joint gap, thickness, or strength requirement exceeds what an autogenous fusion weld can reliably bridge. If the joint is closed and fusion is adequate, filler can be omitted entirely.
Why is argon used so often?
Argon is inert and shields the weld pool and tungsten from atmospheric oxygen and nitrogen. This prevents oxidation and metallurgical degradation, which is essential for clean, sound welds on aluminum, stainless steel, and non-ferrous alloys.