Types of MIG Welding: The Complete Guide to Transfer Modes, Gases, Wires, and Machines

The Four Standard Types of MIG Transfer: Short Circuit, Globular, Spray, and Pulsed Spray

Ask ten welders what “type” of MIG they run and most will answer with a mode name, not a machine. That’s because transfer mode is the single biggest lever you pull on weld quality. The AWS transfer-modes poster maps four standard modes, and nearly every other MIG variant is a rewrite of one of them. Here’s how each behaves at the arc, and where each belongs.

Short-Circuit Transfer (GMAW-S): The Thin-Metal Workhorse

Short circuit is the mode you hear before you see it: a rapid buzz, roughly 20 to 200 cycles a second, as the wire touches the puddle, pinches off a droplet, and the arc extinguishes and re-establishes with every cycle. That on-off rhythm is what keeps heat input low.

Typical settings run 16–22 volts with argon/CO2 mixes like 75/25, 80/20 or 90/10. It welds in every position, handles sheet metal and poor fit-up, and leaves a shallow, wide penetration profile — which is exactly why it’s prone to lack of fusion on thick plate. Bring your baseline in with the complete MIG setup and settings guide before you chase voltage.

Globular Transfer: The Ugly Middle Ground

Crank voltage up without enough argon and droplets grow larger than the wire diameter, detaching by gravity rather than by electromagnetic pinch. The arc crackles, spatter flies, and the bead looks rough. Globular shows up with 100% CO2 or CO2-rich mixes at moderate-to-high voltage, works flat only, and offers deep penetration — but it’s rarely chosen on purpose. It’s a byproduct of drifting past short circuit without reaching spray.

Spray Transfer: Hot, Fast, and Spatter-Free

Spray needs at least 80% argon and generally 25–30 volts or higher. Instead of pinching off big drops, the wire tip tapers to a sharp point and throws thousands of fine droplets smaller than the wire diameter axially across the arc. The sound is a smooth hiss.

Beads come out clean, penetration is deep and finger-shaped, and deposition is high — but it’s flat and horizontal only, on roughly 1/8 in. material and up. NIST droplet-transfer research measured current standard deviation under 10 A for spray modes — the steadiest of the four — against the highest variance for short circuit.

Pulsed Spray Transfer: Spray Quality in Every Position

Pulsed MIG alternates a high peak current, enough to force spray detachment, with a low background current where no metal transfers at all. Pulse rates span roughly 20 to 2,000 pulses per second. Because average current stays low, you get spray-like fusion out of position and on thinner steel without burning through.

One regulatory detail worth knowing: under ASME Section IX (QW-409.2), changing between short-circuiting and spray, globular, or pulsating transfer is an essential variable. Switch modes on a qualified procedure and it needs requalification — proof that mode isn’t a casual setting.

Rule of Thumb: Pick Your Mode in Seconds

• Thin sheet, gaps, or vertical/overhead? Short circuit, 16–22 V.
• 1/8 in. or thicker, flat, production run? Spray, 80%+ argon, 25–30 V+.
• Thick parts but out of position? Pulsed spray.
• Hearing crackle and seeing spatter rain? You’ve landed in globular — add argon or reduce voltage.
• 100% CO2 in the tank? Short circuit or globular only; true spray is off the table.

Screenshot this list, then confirm your results with a visual check of good versus bad MIG welds before you commit a whole part to a new mode.

Advanced and Specialized MIG Types: STT, RMD, CMT, Double-Pulse, and MIG Brazing

Walk through a modern welding supply catalog and you’ll see names that sound like separate processes: STT, RMD, CMT, double-pulse, MIG brazing. They aren’t. Every one of them is still gas metal arc welding — the same continuously fed wire, the same shielding gas, the same molten pool. What changed is the software. Instead of a flat, constant voltage curve, the power source reshapes current and voltage hundreds or thousands of times per second to control exactly how each droplet crosses the arc.

That’s the whole idea behind these advanced types: waveform control. The machine decides when to push hard and when to back off, and your job gets easier because of it. A peer-reviewed welding process profiling study measured how much these controlled waveforms actually change the shop environment, and the numbers are striking. Fume generation came in at roughly 13 mg per gram of electrode for shielded metal arc welding, about 1.5 mg/g for pulsed-spray GMAW, and only about 1 mg/g for CMT. Manganese emissions ranged from 0.45 mg/g for SMAW down to 0.08 mg/g for CMT.

Surface Tension Transfer (STT)

STT is a waveform-controlled short-circuit variant. It measures the arc in real time, drops the current right before the droplet touches the pool so the metal transfers by surface tension rather than by a violent pop, then surges current to wet the puddle out. That low-heat, low-spatter behavior is why it’s credited with handling poor fit-up better than standard short circuit, and why pipeline crews use it for open-root passes where the gap wanders and a burn-through ruins the joint. Expect a real cost premium — STT-capable power sources typically run well above a basic short-circuit machine.

Regulated Metal Deposition (RMD)

RMD is the cousin of STT: same philosophy, different software. It also modulates the short-circuit cycle to keep heat input low while producing a stable, consistent root. On pipe and pressure work, RMD gives welders a root that matches up nicely for the fill passes to follow, with far less cleanup than a stick root. If you’re used to running roots on basic MIG setups, the difference feels like cheating.

Cold Metal Transfer (CMT)

CMT takes the short-circuit idea one step further and physically pulls the wire backward as the droplet detaches. That mechanical retraction means almost no current is needed to break the short, which slashes heat input and spatter. It’s the go-to for very thin sheet metal, dissimilar thickness joints, and coated or heat-sensitive material. As the study above shows, it’s also the cleanest option measured for fume. Welding automation cells and precision fabrication shops gravitate toward it for exactly that reason.

Pulsed MIG and Double-Pulse Waveforms

Standard pulsed spray cycles between a high peak current that detaches a droplet and a low background current where no transfer occurs. The payoff: spray advantages in all positions at a lower average current than a true spray arc needs. Double-pulse goes further, alternating between two pulse conditions. The result is a rhythmic, TIG-like “stacked dime” bead that robotic and automated setups chase for appearance and controlled heat input. For more on controlled, high-deposition automation, see our piece on robotic submerged arc welding.

MIG Brazing

MIG brazing swaps steel wire for a lower-melting-point filler such as silicon bronze. The base metal never melts — the filler just wets and bonds to it. That’s why it dominates on galvanized steel and coated automotive panels, where burning through the zinc coating means corrosion and ugly rework. It requires its own wire, gas, and settings, and it is not intended for structural steel joints.

Two Real-World Scenarios

A pipeline contractor running open-root passes on 6-inch line pipe picks STT or RMD because the root gap on field joints is never perfect. A conventional short arc at that heat would blow through or leave cold lap; the controlled waveform lets the root tie in cleanly with minimal grinding before the fill and cap.

Down the road, a collision repair shop MIG-brazes quarter panels on a galvanized unibody car. Steel wire at fusion temperatures would vaporize the zinc coating and leave bare metal to rust, plus risk panel warping on thin high-strength steel. Silicon bronze filler at lower current joins the panel without destroying the coating, and the joint is easy to dress.

The takeaway: these advanced types aren’t new arc processes. They’re the same GMAW arc, just controlled with far more precision. When they earn their price tag, it’s because of fume, distortion, fit-up, or coating damage — the four problems that quietly cost more than the machine ever will.

MIG vs MAG vs Flux-Cored vs Metal-Cored: The Filler and Process Family Types

Here’s where a lot of confusion starts. The four transfer modes describe how molten metal crosses the arc. They say nothing about what that metal is made of, or what’s protecting the pool. Those are separate decisions, and in the shop they’re the ones people mix up most. One welder says “I’m running flux-core,” another says “I’m running MAG,” and both are describing different axes of the same process. Let’s untangle the family tree.

The AWS A3.0 terminology standard files wire-fed, gas-shielded welding under gas metal arc welding (GMAW), with flux-cored work under flux-cored arc welding (FCAW). Within GMAW, wire construction and shielding choice split the family into distinct types.

Solid-Wire GMAW: MIG and MAG

A solid, bare wire feeds through the gun while an external cylinder shields the pool. When that gas is inert — pure argon or argon/helium — it’s technically MIG. When it’s active and reacts with the weld — CO2 or argon/CO2 mixes — it’s MAG. Most North American welders call all of it MIG, which is fine in conversation but muddy in a procedure.

What changes with MAG is cost and penetration. Lincoln Electric notes that argon-based shielding for axial spray and pulsed spray is more expensive than straight 100% carbon dioxide. CO2 buys deeper penetration and a cheaper bottle, at the price of extra spatter. That trade-off is why farm shops lean on CO2 while precision shops pay for argon mixes.

Flux-Cored: Gas-Shielded (FCAW-G) and Self-Shielded (FCAW-S)

Flux-cored wire is tubular. Instead of a solid metal core, it carries fluxing agents that generate slag and shielding gas as they burn. That single design change splits the family in two.

Gas-shielded flux-cored (FCAW-G) adds an external gas bottle on top of the flux, improving arc stability and bead appearance. In code and in practice it’s generally treated as a globular-transfer process — big droplets, gravity-driven, heavy on deposition. It’s the workhorse of structural steel and shipbuilding.

Self-shielded flux-cored (FCAW-S) needs no gas at all. The flux core protects the pool by itself, which makes it the standard pick for pipeline, bridge, and field work where a bottle is a liability.

Cost is a real differentiator. The PMC process comparison study lists cost per linear meter of weld at $10.89 for gas-shielded flux-cored, $12.37 for short-circuit GMAW, and $31.07 for stick. Flux-cored wins on deposition and cost; MIG wins on cleanliness and control.

Here’s how that plays out in real life. A rancher tried to patch a feed trailer with MIG on a breezy afternoon. The gas drifted, the arc sputtered, and the beads came out porous. He switched to a self-shielded flux-cored wire and welded the same joint clean in one pass — no bottle, no windscreen, no fuss.

Metal-Cored Wire: The High-Deposition Middle Ground

Metal-cored wire looks like flux-cored — tubular — but its core is metallic powder rather than flux. The payoff is flux-cored deposition rates with almost no slag. You get fast fill plus the low cleanup of solid wire, which is why heavy equipment and trailer builders love it. Nearly all metal-cored wire still runs with a gas shield, usually a rich argon/CO2 mix.

Dual-Shield and MIG Brazing Wire

Dual-shield wire combines an outer gas shield, a flux core, and a metallic powder core — three layers of protection built for heavy structural passes. MIG brazing wire is different again: typically silicon bronze, deposited at low heat so the base metal barely fuses. It’s the go-to for galvanized and coated steel and for joining dissimilar metals without burning off the coating. If any of this still sounds interchangeable, our breakdown of flux core vs MIG draws the line clearly.

The Family at a Glance

Pick the filler and shielding family before you pick a transfer mode — because the wire you load into the gun quietly decides which modes are even available to you. Get that order right and the rest of your settings fall into place far faster.

Shielding Gas Types for MIG: How Gas Chemistry Changes the Weld (and the Transfer Mode)

Pick up a MIG torch and you’re holding two decisions at once: what the wire does, and what the gas around it does. Shielding gas is not a consumable afterthought you top up when the cylinder runs dry. It decides which transfer modes are even possible, how the bead sits, how deeply it bites, and how much spatter you grind off Monday morning. Change the gas and you’ve effectively changed the type of MIG welding you’re running, even if the machine, wire, and technique stay identical.

The Gas Families That Actually Matter

• 100% CO2: The budget option and still a workhorse. It supports short circuit and globular transfer only and cannot sustain a true axial spray arc. Expect a wide, deep-penetrating bead and noticeably more spatter.
• Argon/CO2 mixes (75/25, 80/20, 85/15, 90/10): The workhorses for carbon steel. More argon means a smoother arc and a better shot at spray transfer. A true spray arc generally needs at least 80% argon, which is why 85/15 and 90/10 exist.
• Argon/O2 98/2: A thin-sheet favorite. The small oxygen addition stabilizes the arc and improves wetting on light-gauge carbon steel.
• Argon/helium mixes: Helium raises heat input, so it earns its price on thick aluminum and heavy sections where you need more punch without more amps.
• Tri-mix (helium/argon/CO2): Built for stainless, trading cost for smoother wetting and a cleaner bead face.

Argon-rich mixes give smoother, spatter-light beads; CO2-rich shielding trades that polish for penetration and price. That’s why the Lincoln Electric GMAW guide ties gas choice directly to transfer mode rather than treating the two as separate topics.

Contamination: Reading the Symptoms

Most “my MIG welds suddenly went bad” complaints are shielding problems, not machine problems. Oxygen contamination shows up as porosity, a dark or sooty bead, excess spatter, and an arc that wanders. Nitrogen contamination is sneakier: pinhole porosity, an erratic arc, and a brittle, glassy-looking weld that fails a bend test without warning. Both usually trace back to a leaking hose fitting, a plugged nozzle, flow set too low, or wind stripping the gas before it ever reaches the puddle. Outdoors, wind is the big one. Shielding gas blows away easily, which is exactly why windscreens are recommended for pulsed spray in open air. If you fight wind regularly, our gasless MIG welding guide covers when a self-shielded wire is the smarter type choice.

Safety: The Hazard You Can’t See

Shielding gases are heavier than air and quietly displace the oxygen in a tank, pit, or shipping container. OSHA’s welding fume fact sheet warns that helium, argon, and carbon dioxide can displace oxygen and cause suffocation in confined spaces, and that carbon monoxide can form as an additional asphyxiation hazard. The practical rules: never weld in a closed vessel without forced ventilation and an atmosphere monitor, keep cylinders secured and upright, and leak-test every connection with soapy water rather than your ears.

Gas is the cheapest variable to change and the fastest way to change your results. Choose it deliberately, and the transfer mode you wanted actually shows up at the puddle.

Filler Wire Types: Matching ER70S-6, Stainless, Aluminum, and Specialty Wires to the Job

Walk into any welding supply shop and the wire rack tells a misleading story: dozens of spools that look almost identical. They are not. In MIG welding the filler metal is the electrode, which means the wire you thread through the gun becomes part of the finished weld. Choose wrong and you will spend a Saturday chasing porosity, cracking, or a bead that looks fine and fails inspection six months later.

This is the fourth axis of “type” in MIG welding. Transfer mode decides how metal crosses the arc, gas chemistry decides arc behavior, and the wire decides what the weld actually is. Every filler falls under a classification spelled out in the AWS A3.0 terminology standard, and reading that code takes about ten seconds once you know the pattern.

Carbon Steel: ER70S-6 and ER70S-3

ER70S-6 is the most widely used general-purpose carbon steel MIG wire, and the reason is chemistry. It carries higher silicon and manganese deoxidizers than ER70S-3, which lets it shrug off light mill scale, oil film, and mild rust that would send a leaner wire straight into porosity. The “70” means 70,000 psi minimum tensile; the “S” means solid wire; the “6” is the chemistry suffix.

ER70S-3 is the lower-silicon alternative. On clean, freshly ground steel it lays a smoother, flatter bead with slightly less silicon island glass on the surface, and a lot of shops prefer it for cosmetic work where the metal is spotless. The tradeoff is forgiveness. Contaminated plate punishes S-3 far faster than S-6.

A fabricator I know burned through two spools of rusty ER70S-3 on a trailer frame, fighting pinhole porosity the whole way. The gas was fine, the machine was fine. Switching to a fresh, dry spool of ER70S-6 dried up the porosity on the next pass. The wire had been the variable all along.

For higher-strength low-alloy work, ER80S-D2 steps up the tensile strength with molybdenum, but it demands matching procedure controls and preheat discipline, so it is not a “grab whatever’s on the shelf” filler. For a deeper look at what each wire is actually made of, see our guide to what MIG welding wire is made of.

Stainless: 308L and 316L

Stainless MIG wires match base metals almost one-to-one. 308L pairs with 304 stainless, the everyday food-grade and architectural alloy. 316L pairs with 316 and adds molybdenum for better corrosion resistance in chloride-heavy environments like marine work and chemical plants. The “L” means low carbon, which cuts the risk of carbide precipitation and sensitization near the weld.

Aluminum: ER4043 and ER5356

Aluminum splits into two common families. ER4043 runs cooler, wets out and flows more readily, and is more tolerant of cracking on heat-treatable alloys like 6061. ER5356 is stronger, feeds slightly better, and anodizes to a cleaner color match, which is why it dominates anodized parts and marine structures.

If aluminum is on your bench, our breakdown of DC welding aluminum covers the polarity and setup side of the equation.

Specialty Wires: MIG Brazing and Hardfacing

Silicon bronze filler is the backbone of MIG brazing, joining thin and galvanized sheet at temperatures low enough to avoid vaporizing the zinc coating. Hardfacing wires lay wear-resistant overlays on buckets, plows, and crusher parts, trading ductility for abrasion resistance.

Wire Diameter, Storage, and Feeding

Diameter scales with thickness and voltage. Match small wire to thin metal, larger wire to thick plate, and always feed clean stock through a matched liner and fresh contact tip. For aluminum, a Teflon liner and a dedicated lubricator keep soft wire moving without shaving. Store every spool dry and off the floor; rust and moisture migrate straight into your weld as porosity.

One more detail worth knowing: electrode behavior itself is measurable. The NIST droplet transfer research shows that wire and transfer variables shift arc stability in ways you can actually quantify, not just feel. Match the wire to the job, keep it clean, and the arc will do most of the work for you.

MIG Machine Types: Transformers, Inverters, Synergic Multiprocess, and Portable Units

Transfer mode, gas, and wire get all the attention, but there is a fourth axis hiding in plain sight: the machine itself. The power source you plug in decides which modes you can reach, how long you can weld before the fan starts screaming, and how much you pay. Two welders running identical wire and gas can produce wildly different arcs simply because one is a basic transformer box and the other a synergic inverter.

Transformer vs. Inverter: The Core Split

Transformer-based MIG welders are the old guard. They step down mains voltage through a heavy copper-and-steel transformer and put out a rock-steady constant-voltage arc. They are tough, simple, and cheap on the used market, which is why so many garage machines are transformer units. The trade-offs are weight, lower electrical efficiency, and limited waveform control.

Inverter machines convert incoming AC to DC, then switch it at high frequency to build a far lighter unit with precise control over the output waveform. That control is exactly what opens the door to pulsed and advanced transfer modes. The Lincoln Electric GMAW guide shows how closely arc behavior tracks the power supply, and pulse options are not available on most basic transformers. As AWS forum experts note, pulse-capable power supplies can cost two to three times more than a conventional constant-voltage machine.

Synergic and Multiprocess: One-Knob and Do-It-All Machines

Synergic machines take the guesswork out of the dials. You enter the base metal, wire diameter, and shielding gas, and the machine sets voltage and pulse parameters for you; the operator then adjusts one control for the heat they want. For shops hiring less-experienced hands, that is a training shortcut as much as a convenience.

Multiprocess units bundle GMAW, TIG, and stick into one box, ideal when you need flexibility without three separate machines. Just remember that the electronics matter enough that ASME Section IX treats a change in power source model as an essential variable for GMAW procedures, per the AWS A3.0M/A3.0 standard. Swap the machine and a qualified procedure may need requalification.

Field and Portable Machines

Engine-driven welders and suitcase wire feeders bring MIG to pipelines, farms, and sites with no mains power. A suitcase feeder is a compact wire drive that rides near the work and pulls from a spool; pair it with a generator and you have mobile MIG. Spool guns place the spool right at the torch, which solves the feeding headaches of soft aluminum wire. For a visual breakdown of how current density creates each mode, the AWS GMAW transfer modes poster is worth pinning above the bench.

Picture a hobbyist who mostly builds trailers buying a 300 A industrial inverter, only to find his 120 V garage circuit cannot feed it and he never needs more than 200 A. A small fabrication shop running two shifts, meanwhile, buys a synergic inverter not for more power but to cut training time: new hires dial in material, wire, and gas, and start laying clean beads on day one.

Buy for duty cycle and modes, not peak amps. Match input voltage to your shop wiring and confirm the machine can run the transfer mode your work demands; pulsed and advanced modes are locked behind inverter electronics. If you are still learning the ropes, work through our MIG Welding at Home guide before spending big, and if running wire is new to you, our beginner’s guide to using a wire welder covers setup and travel speed. Because the torch is where arc meets metal, keep fresh consumables on hand too — this contact tip guide explains wear and selection. Choose the machine that fits the work, not the spec sheet.

Benefits, Challenges, and the Mistakes That Ruin MIG Welds (Plus the Fixes)

MIG has a split reputation. Beginners hear it’s the easiest process to learn, buy a machine, and produce beads that look like a flock of seagulls landed on the plate. Experienced fabricators know a dialed-in MIG setup can outrun stick so badly it isn’t a fair fight. Both are true. What separates them is understanding where MIG wins, where it struggles, and how to read a bad bead before it becomes a bad part.

Where MIG Earns Its Keep

Start with economics. One widely cited study put a stick (SMAW) weld at $31.07 per linear meter versus $12.37 for short-circuit GMAW, roughly a 60% reduction. That gap comes from deposition rate, continuous wire feeding, and not stopping every few inches to swap electrodes and chip slag.

The rest of MIG’s strengths stack up fast:

• Speed and deposition — continuously fed wire deposits far more metal per hour than stick, with no stub loss.
• All-position capability — short-circuit transfer handles vertical and overhead; pulsed MIG sprays in every position at reduced average current.
• Minimal slag — little to no chipping, which shortens cleaning time dramatically.
• Short learning curve — most operators get decent beads within hours, especially on home MIG setups.

The Honest Downsides (and Why They Happen)

Short-circuit transfer runs at low heat input, and low heat input is exactly what makes it prone to fusion defects. Per AWS industry discussion, that includes incomplete fusion, incomplete joint penetration, and overlap — the weld sits on top of the metal instead of into it. On thick steel this is the most common failure mode, and it’s invisible from the outside.

MIG is also fussy about gas. Lose your shielding to wind, a kinked liner, or a plugged nozzle and porosity appears immediately. Distortion follows accumulated heat input. And the power source is a bottleneck: pulse capability often costs significantly more than a conventional machine, so many shops simply live without it.

MIG Troubleshooting Table

If your defect isn’t here, a broader overlap welding defect guide and a side-by-side of good versus bad MIG welds will help you diagnose by appearance alone.

Common Mistakes That Kill MIG Welds

• Wrong transfer mode for the thickness — using short-circuit on ½-inch plate and wondering why it won’t penetrate.
• Wrong polarity — solid-wire MIG is DCEP; getting this backwards ruins the arc.
• Too much stick-out — beyond about ½ inch, you lose penetration and shielding.
• Dirty metal — mill scale, rust, paint, and oil all become porosity.
• Ignoring duty cycle — a 60% duty cycle at 150 A is six welding minutes out of ten, not a suggestion.
• Never touching the inductance setting — this one deserves its own note.

Keep your consumables honest, too. A worn contact tip causes erratic arcs, bird-nesting, and spatter that no setting can fix — our contact tip selection and troubleshooting guide covers when to replace it.

Safety: Fume, Chromium, and Manganese

MIG fume is not something to shrug off. OSHA’s welding fume fact sheet links prolonged exposure to eye, nose and throat irritation, dizziness and nausea, lung damage, and cancers of the lung, larynx, and urinary tract. The traditional total fume limit is 5 mg/m³ as an 8-hour time-weighted average, measured in the breathing zone.

Stainless and coated steels raise the stakes. Welding stainless releases hexavalent chromium, and OSHA sets a permissible exposure limit of 5 µg/m³ as an 8-hour TWA, with an action level of 2.5 µg/m³. Manganese is the other concern: NIOSH recommends a REL of 1 mg/m³ as a TWA with a 3 mg/m³ short-term limit, and prolonged exposure can produce Parkinson’s-like symptoms. NIOSH’s guidance is blunt — keep all welding emissions as low as feasible with engineering controls first, respirators second.

Local exhaust ventilation, a proper respirator, and correct eye protection are not optional extras. They’re part of the process.

The good news? Nearly every problem above has a cause you can control. Match the mode to the thickness, match the gas to the mode, keep your consumables fresh, and MIG rewards you with speed that stick welding simply can’t touch.

How to Choose the Right Type of MIG Welding: Decision Framework, Settings, Safety, and Conclusion

You now know the four standard transfer modes, the advanced waveforms, the gas families, the wire classifications, and the machine classes. The last step is turning that knowledge into a decision you can make in thirty seconds at the bench.

The Step-by-Step Decision Framework

1. Identify the base metal and thickness. Mild steel at 18 gauge and 3/8 in. plate are different worlds. Short circuit and pulsed modes cover thin sheet down to about 0.9 mm (0.035 in.), while axial spray suits thicker plate, according to the Lincoln Electric GMAW guide and the AWS transfer modes poster.
2. Confirm position and access. Flat and horizontal open the door to spray. Vertical-up, overhead, or tight corners push you toward short circuit or pulse.
3. Choose the transfer mode. This is the single biggest quality decision — and remember, changing from or to short-circuiting transfer is an essential variable under ASME Section IX, so procedure-qualified work must requalify.
4. Choose the gas. CO2-rich mixes for short circuit and globular; roughly 80% argon minimum for true spray.
5. Choose the wire diameter. Thin metal wants 0.023–0.030 in.; heavier sections reward 0.035–0.045 in.
6. Set voltage and wire feed speed (WFS). Voltage sets arc length, WFS sets current.
7. Verify duty cycle. A 60%-at-150 A machine welds six minutes out of ten at that amperage.
8. Verify fume control. Ventilation, local exhaust, or a respirator before the first arc.

Four Worked Examples With Real Numbers

• 18-gauge sheet: short circuit, 75/25 argon/CO2, 0.023–0.030 in. ER70S-6, roughly 16–18 V, fast travel, low spatter.
• 3/8 in. plate: spray transfer flat and horizontal at 25–30 V+ with 90/10 or 95/5 argon, 0.035–0.045 in. wire. Switch to pulsed spray for vertical-up so you keep spray arc quality at lower average current.
• Aluminum: spool gun or push-pull torch, 100% argon, ER4043 or ER5356, and noticeably higher travel speed to outrun the heat.
• Galvanized panels: MIG brazing with silicon bronze at low heat to avoid burning off the coating and releasing zinc fume.

Starter Settings Table

Productivity and Cost Tips That Pay for Themselves

• Buy shielding gas in bulk cylinders rather than swapping small ones weekly.
• Size the wire to the job; over-thick wire on thin metal causes burn-through and wasted filler.
• Keep contact tips and liners fresh — worn tips arc erratically, as covered in Contact Tip Welding.
• Mind stick-out. Too much and the arc wanders; too little and you cook the tip.
• For outdoor jobs where wind defeats gas shielding, consider gasless MIG welding instead of fighting the breeze.

The Safety Checklist Before You Pull the Trigger

• Ventilation or local exhaust at the arc. OSHA’s welding fume fact sheet notes the total fume PEL is 5 mg/m³ as an 8-hour TWA.
• Respirator when warranted. Stainless raises hexavalent chromium exposure, with a PEL of just 5 µg/m³ as an 8-hour TWA.
• Leathers, gloves, and an auto-darkening helmet, plus proper protective eyewear for welding.
• Solid grounding and dry gloves.
• In confined spaces, watch for gas displacement. CO2, argon, and helium are asphyxiants, per NIOSH.

A well-planned booth makes all of this easier — see Welding Facilities.

The Bottom Line: MIG Type Is a Decision, Not a Setting

Dan’s golf-ball hole wasn’t a machine failure. It was a decision failure: the wrong type of MIG welding for the thickness in front of him. Match mode, gas, wire, and machine to the job, and you stop creating rework. Study MIG welding at home for setup depth, then build skill deliberately with a plan from Welding Practice.

Bookmark the Welding Gallery MIG hub, subscribe for more guides, and this month, practice one new transfer mode you’ve never run.

Frequently Asked Questions

What are the main types of MIG welding?

MIG welding types can be grouped three ways. By transfer mode there are four standard types: short circuit, globular, spray, and pulsed spray. By filler and process family there is solid-wire MIG, metal-cored, gas-shielded flux-cored, self-shielded flux-cored, and MIG brazing. By machine there are transformer, inverter, synergic and multiprocess power sources, plus engine-driven and portable setups.

Which type of MIG transfer is best for beginners?

Short-circuit transfer is the most forgiving starting point because it works in all positions, handles thin sheet and gaps well, and needs only a simple argon/CO2 mix. Start around 16-22 volts on 0.023 to 0.030 in. wire and practice on scrap until the bacon-frying sound is consistent.

Can you MIG weld out of position with spray transfer?

No. True axial spray transfer has such high heat input that the weld pool is too fluid for vertical or overhead work, so it is limited to flat and horizontal positions. Pulsed spray solves this by cycling between peak and background current, giving spray-quality welds in all positions at lower average heat.

What shielding gas should I use for MIG welding?

For carbon steel, a 75/25 to 90/10 argon/CO2 mix covers most short-circuit and spray work, while 100% CO2 is cheaper and gives deeper penetration but more spatter and no true spray arc. Aluminum generally uses 100% argon, often with helium for heavy sections, and stainless commonly uses argon-based tri-mix or low-CO2 blends.

Is MIG welding the same as MAG welding?

No, although the terms are used interchangeably in North America. MIG uses inert shielding gas such as argon or helium, while MAG uses active gases like CO2 or oxygen-bearing mixes. Since most steel MIG work uses CO2-bearing gas, it is technically MAG welding.

What is the difference between MIG and flux-cored welding?

MIG uses a solid wire and always needs external shielding gas, making it clean and spatter-light indoors. Flux-cored wire has a flux core that creates its own shielding and slag, and self-shielded versions need no gas at all, which makes them far more wind-tolerant for field and structural work.

Is pulsed MIG worth the extra cost?

If you weld a lot of thin sheet, stainless, or aluminum, or need spray-quality welds in vertical and overhead positions, yes. Pulse-capable power sources have historically cost two to three times more than basic units, but they reduce spatter, distortion, and rework on demanding work.

Can you MIG weld without gas?

You cannot run standard solid-wire MIG without shielding gas because the molten pool would be contaminated by air, causing porosity and a weak weld. The no-gas option is self-shielded flux-cored wire, which protects the pool through its flux core and is designed for outdoor and field use.

Which MIG transfer mode produces the least fume?

Research comparing processes found the lowest fume generation per gram of electrode with Cold Metal Transfer (about 1 mg/g) and pulsed spray MIG (about 1.5 mg/g), while shielded metal arc welding was highest at roughly 13 mg/g. Short-circuit MIG with 100% CO2 produced significantly more fume than argon-mix short circuit.

Does changing the MIG transfer mode affect welding procedure qualification?

Yes. Under ASME Section IX, a change from spray, globular or pulsating transfer to short-circuiting transfer, or the reverse, is treated as an essential variable, meaning the welding procedure must be requalified. Changes among spray, globular and pulsed modes generally do not require requalification.