General MIG amp ballparks for ~3 mm mild steel — and why duty cycle at that amp matters for continuous runs versus tacks. Research guidance only, not a WPS.
Affiliate disclosure: This page contains affiliate links. We may earn a commission if you buy through them. Nothing here is a paid ranking. Gear cards below are research / Untested — not personal on-site reviews. Amp and duty figures are general education, not a welding procedure specification or machine certificate.
Research ranges only — common training-style mild-steel MIG ballparks with solid wire. Joint type, position, wire diameter, gas, and technique shift the real setting. Not a procedure.
| Mild steel thickness (approx.) | MIG amp ballpark (research) | Notes |
|---|---|---|
| ~1–1.5 mm | ~40–80 A | Thin sheet; burn-through risk if hot |
| ~2 mm | ~70–110 A | Light fab / brackets |
| ~3 mm | ~90–140 A | Focus of this page — mid-range MIG talk |
| ~4–5 mm | ~120–180 A | Often wants more duty headroom |
| ~6 mm+ | ~160 A+ (multi-pass common) | Machine rating and prep matter more |
Example used in the diagram: 40% duty at a stated amp ≈ 4 minutes weld / 6 minutes cool in a 10-minute window at that rating. Manufacturers test differently — always read the specific unit’s manual.
Research placement only. No on-site use claims. Links go to Machine Mart via Awin.
Entry 100 A-class research pick for lighter domestic/site seams. Check published duty at the amps you actually need for ~3 mm — Untested.
Untested View on Machine Mart
Higher-amp multi-process research option when ~3 mm continuous runs need more headroom than a small entry MIG. Untested.
Untested View on Machine MartResearch and training materials often discuss roughly 90–140 A as a ballpark for ~3 mm mild steel with common solid MIG wire diameters, depending on joint type, position, and wire size. Treat that as a research range to compare against machine labels — not a procedure for your job.
In a simplified 10-minute window at the stated amp, 40% duty means about 4 minutes of welding and 6 minutes of cooling at that rating. Manufacturers publish duty differently; always read the plate and manual for the unit you buy. This is education, not a certificate.
Short tacks leave natural cool time. Long beads or production seams keep the machine near its rated amp for longer, so a low duty rating at that amp forces pauses or thermal cut-out. Size amp headroom to how you actually weld, not only peak amps on the box.
Some light domestic and site jobs around 2–3 mm are discussed with entry 100 A-class machines, especially with short seams. Continuous heavier runs may want more amp and duty headroom. We have not tested the named products on site; compare labels and manuals yourself.
No. Amp tables here are general mild-steel MIG research ballparks for UK site fab discussion. Coded work follows your written WPS and employer procedures.
No. Figures are framed as research ranges from common training and manufacturer-style guidance. Product cards are Untested research placements only.