Process
MIG / TIG assembly
Filler-metal welds for 4–14 mm frames, fixtures, and joints that a resistance welder cannot reach or should not run. Tack, then fusion — and expect the form to move.
What MIG / TIG assembly is on a wire form
After the centerline is bent, some parts still need a joint that is not a cross-wire nugget: a frame corner, a wire to a plate, a stainless fixture, a repairable field weld. MIG (GMAW) and TIG (GTAW) put filler into that joint.
This is fabrication sitting on top of forming. Cycle time is slower than resistance welding. Distortion is higher. Inspection looks like a weldment: size, length, and sometimes dye penetrant — not a peel test on a grid.
When filler is the right call
- The joint is not a clean wire-on-wire cross.
- Alloy is a poor resistance candidate (some 300-series, 330, nickel).
- You need a fillet you can specify and see.
- Electrode access for resistance weld is blocked by the 3D path.
- The assembly includes tube, plate, or a bought-in stamping.
Tacks exist to hold a fixture. They are not a substitute for the specified weld. If the print says “tack weld,” say how many and where, or you will get whatever held in the shop fixture.
What changes from 4 to 14 mm
| Diameter | Inch | Fusion weld |
|---|---|---|
| 4 mm | 0.157 in | Easy to blow through. TIG or small MIG; heat input is the process. |
| 8 mm | 0.315 in | Standard frame tacks and fillets. Fixture the span or the bow shows up after cool-down. |
| 12 mm | 0.472 in | Real weldment. Preheat and sequence matter on carbon; stainless still moves. |
| 14 mm | 0.551 in | Treat it as structural fabrication. Resistance weld may still win on a grid — not on a corner. |
Print, sequence, and distortion
- Weld symbol, size, and length — not “weld to suit”
- Filler / process if the alloy demands it (especially stainless and nickel)
- Finish: as-welded, ground flush on a named face, then plate
- Datums after weld, not only after form — the part will move
A 3D CNC program can be perfect and the MIG pass still pulls a 12 mm frame out of the hole pattern. Inspect the welded state, or fixture during weld and check after.
Related
- Mesh grids and cable trays
- Resistance welding
- 3D CNC wire forming
- Heat treating — stress relief after a heavy weldment