MIG/MAG Process (135/136): Fundamentals and Parameters
Introduction
The MIG/MAG process is the most widely used in the metalworking industry. In EN ISO 4063:
- 135 — MAG (Metal Active Gas): active gas (CO₂ or Ar+CO₂/O₂ mixture) → carbon and low-alloy steels
- 136 — MAG with flux-cored wire (FCAW): tubular wire with internal flux
- 131 — MIG (Metal Inert Gas): inert gas (Ar or Ar+He) → aluminium, stainless steel, copper
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Metal Transfer Modes
| Mode | Voltage | Current | Application |
|---|---|---|---|
| Short-circuit (dip) | 14–22 V | 60–180 A | Thin sections, all positions |
| Globular | 22–26 V | 180–280 A | Flat position, rarely used |
| Spray | >26 V | >280 A | Flat/horizontal, high deposition |
| Pulsed | Variable | Variable | All positions, stainless and aluminium |
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Shielding Gases (EN ISO 14175)
| Mixture | EN designation | Application |
|---|---|---|
| Pure CO₂ | C1 | Carbon steel (economical) |
| Ar + 18% CO₂ | M21 | Carbon steel |
| Ar + 2% O₂ | M13 | Austenitic stainless |
| Pure Ar | I1 | Aluminium, copper |
| Ar + 30–70% He | I3 | Aluminium (better fusion) |
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Main Parameters
Arc voltage (U): controls bead geometry. Low voltage → narrow, convex bead; high voltage → wide, flat bead.
Wire feed speed (WFS): determines welding current for a given wire diameter.
Travel speed (TS): controls heat input: $$Q = \frac{U \times I}{TS \times 1000} \times \eta \quad [kJ/mm]$$
Thermal efficiency η: 0.8 for MAG.
Contact tip to work distance (CTWD / stick-out): typically 10–20 mm.
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Typical Parameters (MAG, ER70S-6 wire Ø1.2 mm)
| Thickness (mm) | Voltage (V) | Current (A) | WFS (m/min) | TS (cm/min) | Heat input (kJ/mm) |
|---|---|---|---|---|---|
| 2 | 17–19 | 90–120 | 4–6 | 40–60 | 0.15–0.25 |
| 4 | 20–22 | 150–180 | 6–8 | 30–45 | 0.25–0.40 |
| 6 | 22–25 | 180–220 | 8–10 | 25–35 | 0.35–0.55 |
| 10 | 24–27 | 220–270 | 10–13 | 20–30 | 0.50–0.80 |
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Consumables — Solid Wires (EN ISO 14341)
| EN designation | Min. Rm (MPa) | Application |
|---|---|---|
| G 42 2 M21 3Si1 | 420 | General carbon steel |
| G 46 2 M21 4Si1 | 460 | Carbon steel (better wetting) |
| G 50 4 M21 6 | 500 | Low-alloy steel |
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Reference Standards
- EN ISO 4063:2010 — Welding and allied processes. Nomenclature of processes
- EN ISO 14175:2008 — Welding consumables. Gases and gas mixtures
- EN ISO 14341:2011 — Welding consumables. Wire electrodes and weld deposits for MAG welding
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