Three weld types, three jobs. Where each lives in a luminaire body, a switchgear cubicle, or a steel frame, and the spec line that should pick for you.
Gas tungsten arc, single-pass on thin stainless and aluminium. Beautiful bead, but a third the speed of MIG. Reserve it for joints the customer can see.
Gas metal arc, continuous wire feed. Works on 0.8–25 mm steel. Spatter cleanup is the trade. 80% of enclosure and frame work in any Saudi shop is MIG.
Resistance weld through overlapping sheet, no filler. Used inside cabinets where the joint never shows. 0.5 sec per nugget, no cleanup.
Mill scale, oil, primer, all defects under the bead. Grind to bright metal before any process. Skipping prep is what causes porosity nobody can chase down later.
Indicative comparison for stitching 3 mm carbon steel parts.
| Process | Thickness · Speed | Cost / m |
|---|---|---|
| TIG (GTAW) | 0.5–8 mm · 0.1–0.3 m/min | 3–4× MIG, slowest, cleanest |
| MIG (GMAW) | 0.8–25 mm · 0.3–1.5 m/min | Baseline production cost |
| Spot (RSW) | 0.5–3 mm overlap · per nugget | 0.3× MIG, fast, no filler |
| Stick (SMAW) | 3–25 mm · 0.2–0.5 m/min | Site repair, no shielding gas |
| Laser hybrid | 2–12 mm · 1.5–4 m/min | 10× MIG capital, narrow HAZ |
Designers learn these the slow way, through warpage, porosity, and rework.
A weld is a localised pour of molten metal. As it cools, it contracts and pulls the parent metal with it. Long continuous welds warp panels. Use stitch welds (20 mm on, 60 mm off) where strength allows.
Chromium oxidises instantly at weld temperature. Argon shielding at 15 L/min protects mild steel, but stainless needs 20–25 L/min, and a back-purge if the inside surface sees food, gas, or chemicals.
Aluminium melts at 660 °C but its oxide melts at 2,070 °C. A constant arc burns through before the oxide breaks. Pulsed MIG punches through the oxide on each pulse, the only reliable way for <3 mm aluminium.
"Weld here" is not a spec. AWS A2.4 or ISO 2553 weld symbols define fillet/butt, throat thickness, both-sides, length, pitch. Without the symbol, the welder guesses and the QA inspector argues.
A 1 mm gap on a butt joint takes 3× the filler, leaves porosity, and warps more. 0.1 mm fit-up tolerance, tack every 100 mm, then run the full weld. Spend time at the fixture, not the grinder.
Our welding bay runs 16 MIG stations, 4 TIG (inverter, AC/DC for aluminium), and a Tecna spot welder. WPS-qualified to ISO 15614, NDT by liquid penetrant on every visible joint.
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