Choose a welder by matching the process to your material and the quality you need: MIG for fast, easy general fabrication and steel work; TIG for precise, clean welds on thin material, stainless steel and aluminium; MMA (stick) for portable site work and outdoor welding; a multi-process machine when your jobs vary; and laser welding for high-volume thin sheet. Beyond process, the machine itself must suit your material thickness (amperage), how long you weld continuously (duty cycle), your power supply (single-phase 230V or three-phase 400V), portability needs, skill level and total budget including running costs.
This page gives you a decision framework so you can specify the right machine the first time rather than learning the hard way.
Which welding process should I choose?
Pick the process from two questions: what material am I joining, and how good does the weld need to look and perform?
- MIG/MAG (GMAW) is the workhorse of general fabrication. It’s the easiest to learn, lays metal down quickly and copes well with mild steel from roughly 0.8mm up to thick plate. With the right wire and gas it also handles stainless and aluminium. Choose MIG for production, repairs and anyone who needs results fast.
- TIG (GTAW) gives you the most control and the cleanest, most precise welds. It’s the process for thin sheet, stainless steel, aluminium, exposed welds that must look good, and code-quality work. TIG is slower and harder to master, but nothing else matches it for finesse.
- MMA / stick (SMAW) is the most portable and forgiving of dirty, rusty or outdoor conditions. There’s no shielding gas to blow away, so it’s the default for site work, structural steel and maintenance away from a clean workshop. It excels on thicker steel and is cheap to get started with.
If your work spans several of these, a multi-process welder runs MIG, MMA and often TIG from one box. For repetitive high-volume thin-gauge sheet, laser welding delivers speed and minimal distortion at a higher capital cost.
Read more on each in our MIG welders guide, TIG welders guide, MMA welders guide, multi-process welders guide and laser welding guide.
MIG vs TIG vs MMA: how do they compare?
| Factor | MIG/MAG | TIG | MMA (stick) |
|---|---|---|---|
| Best for | General fabrication, production, steel | Thin material, stainless, aluminium, fine work | Site work, outdoors, thick steel, repairs |
| Ease of learning | Easy | Hard | Moderate |
| Speed | Fast | Slow | Moderate |
| Weld appearance | Good | Excellent | Functional |
| Thin material | Good (with control) | Excellent | Poor below ~2mm |
| Outdoor/windy | Poor (gas blows away) | Poor | Excellent (no gas) |
| Consumables | Wire + shielding gas | Tungsten + filler + gas | Coated electrodes only |
| Typical skill barrier | Low | High | Low–moderate |
The short version: MIG for speed and ease, TIG for precision, MMA for portability. Most workshops end up owning more than one, which is exactly why multi-process machines are popular.
How do I match machine amperage to material thickness?
Amperage capacity decides how thick you can weld. As a broad rule of thumb for steel, you need roughly 40 amps per millimetre of thickness for a single pass, though joint type, technique and multi-pass welding all shift this.
- A 160–180A single-phase machine comfortably handles sheet and light fabrication up to around 5–6mm.
- A 200–250A machine covers most general fabrication.
- 300A and above, usually three-phase, is for heavy plate and continuous industrial work.
Don’t just buy on peak amperage. A machine rated at 250A maximum may only deliver that briefly. What matters is how much current you get continuously, which brings us to duty cycle.
What duty cycle do I need?
Duty cycle is the percentage of a ten-minute period a machine can weld at a given current before it must cool down. A welder rated 200A at 40% duty cycle can weld at 200A for 4 minutes, then needs 6 minutes to cool.
- Light/occasional use: a modest duty cycle (30–40% at your working current) is fine for short welds and DIY-grade tasks.
- Production and long runs: look for a high duty cycle (60%+) at the amperage you actually weld at, not just at a low figure.
The trap is reading the headline rating. Always check duty cycle at your real working amperage, because manufacturers often quote a high duty cycle at a low current and a low one at maximum current. For continuous professional fabrication, undersizing duty cycle is the most common and most frustrating mistake.
Single-phase 230V or three-phase 400V?
This is dictated by your premises and your amperage needs.
- Single-phase 230V is what you have at home and in most small workshops. It’s convenient and portable but limits you to roughly 250A for MIG/MMA, with duty-cycle compromises at the top end.
- Three-phase 400V is found in industrial units and unlocks higher amperage, better duty cycles and more efficient, stable power for heavy and continuous work.
If you only have single-phase, size your expectations accordingly. If you have three-phase available, a three-phase machine is almost always the better long-term choice for serious fabrication. Confirm your supply before buying, including the rating of the circuit and plug, as a high-amperage machine can demand more than a standard 13A or 16A socket provides.
How important is portability?
Match the machine’s weight and power needs to where the work happens.
- On-site, outdoors or up scaffolding: prioritise a light, single-phase or inverter MMA machine, or an engine-driven welder where there’s no mains at all. MMA wins here because there’s no gas bottle to lug or shield from wind.
- Fixed workshop: weight matters less, so you can choose a larger, higher-duty machine and gain capability.
Modern inverter technology has made even powerful machines dramatically lighter and more efficient than older transformer units, so portability and power are no longer the trade-off they once were.
What’s the real budget, including running costs?
The sticker price is only part of the cost. Factor in:
- Shielding gas (MIG and TIG) — bottle rental or purchase plus refills. MMA needs none, which is part of its appeal for occasional users.
- Consumables — MIG wire, TIG tungstens and filler rods, MMA electrodes, plus contact tips, nozzles, liners and tungsten grinding.
- Power — three-phase machines are more efficient under heavy load.
- PPE and ancillaries — a good auto-darkening helmet, gloves, regulators and clamps.
Browse our welding consumables range to estimate ongoing costs for each process. A cheap machine that’s wrong for the job costs far more in wasted wire, rework and downtime than the right machine bought once.
How does skill level affect the choice?
Be honest about who’s welding.
- Beginners get results fastest with MIG — it’s the most forgiving and the quickest to a usable weld.
- MMA is straightforward to start but takes practice to run a clean bead and control slag.
- TIG has the steepest learning curve; it rewards practice with unmatched quality but frustrates newcomers expecting instant results.
If a machine will be shared across a team of mixed ability, a MIG or multi-process unit usually serves the widest range of users.
Putting it together
Work through the framework in order: process (material + quality), then amperage (thickness), duty cycle (how long you weld), power supply (single or three-phase), portability, budget with running costs, and skill level. Get those right and the shortlist almost writes itself.
Weldability SIF supplies machines across all these processes, and our team can help you match a specific model to your work. [VERIFY: specific Weldability SIF machine ranges, models and any advisory/specification service to reference here.] Start with our welding machines hub to compare options, or read the dedicated guides linked above.