Metal Inert Gas (MIG) Welding Process: A Comprehensive Guide to GMAW Techniques, Applications & Safety

A single bad weld can turn a simple repair into a costly failure. For decades, Metal Inert Gas (MIG) welding has offered a faster, cleaner way to join metals, but mastering it takes more than just pulling a trigger.

Introduction to the Metal Inert Gas (MIG) Welding Process

A fabricator can pull a trigger on a MIG gun and lay down a quarter-inch fillet weld in seconds. MIG is the most widely used welding process in the world, and the reason is speed. But speed only matters when the bead is strong and the welder understands the process behind it.

So what is the metal inert gas welding process? It is a fusion welding process where a continuously fed consumable wire electrode is melted by an electric arc and shielded from the air by an externally supplied gas. The welder feeds wire steadily and moves along the joint.

What “MIG” Actually Stands For

Metal Inert Gas welding is the shop-floor name. The formal, standardized name is Gas Metal Arc Welding (GMAW), from the American Welding Society, whose AWS A3.0M standard defines the family of arc welding processes using a continuously fed metal electrode and an externally supplied shielding gas. That family also includes FCAW and Submerged Arc Welding (SAW), which share the wire feed but shield differently.

Within GMAW, the gas is either inert (argon, helium) or active (CO2, or mixtures containing CO2 or oxygen). Inert gas makes it MIG; active gas makes it MAG, for Metal Active Gas. Same machine, same process. Only the gas changes, and that changes penetration, spatter, bead shape, and which metals you weld well.

MIG is not a brand name. The same machine gets called MIG, MAG, GMAW, wire feed welding, or gas metal welding depending on country and trade. Outside North America, MIG/MAG is the standard pairing, and the TWI job knowledge guide on MIG welding follows the same convention.

How the Process Fits Alongside Other Welding Methods

• Shielded Metal Arc Welding (SMAW), or stick: a hand-consumed electrode, slower but forgiving in dirty, outdoor, rusty conditions.
• Gas Tungsten Arc Welding (GTAW), or TIG: a non-consumable tungsten makes the arc while filler rod is added by hand. Precise welds, but more skill and more time.
• Gas Metal Arc Welding (GMAW), the subject of this guide: wire feeds automatically, the arc does the melting, gas protects the puddle. The balance point between deposition speed and control.
• Flux Cored Arc Welding (FCAW): similar wire-feed handling, but flux inside the wire creates its own shielding, so it works outdoors and on thick, dirty steel.

That middle position is why MIG became the default in fabrication shops, automotive repair, and general manufacturing. A fabricator can run a whole job on MIG, from 16 gauge sheet to an inch of plate, without changing machines. Fewer process changes means fewer variables and more consistent results.

A Short History of MIG Welding

MIG was developed and patented for aluminum welding in the late 1940s. Before MIG, aluminum was hard to weld: high thermal conductivity pulled heat from the weld zone faster than it could be replaced, and the oxide layer reformed the moment it met air. TIG could manage, but production shops had no efficient way to join it.

The breakthrough combined a continuously fed consumable wire with an inert gas blanket. Inert gas such as argon does not react with the molten pool, so it excluded the atmosphere without contaminating the weld. Continuous wire also solved heat input, because deposition could be controlled without electrode changes.

Adoption spread through the 1950s and 1960s as semi-automatic and then fully automatic wire feeders, constant-voltage power sources, and flux-cored wire pushed the process into structural steel, shipbuilding, and heavy equipment. By the 1980s and 1990s, pulsed spray transfer and waveform control took GMAW into TIG territory: thin-gauge stainless, aluminum trailer bodies, and aerospace sheet metal.

Today GMAW covers everything from 0.8 mm wire welding 0.6 mm aluminum sheet in a body shop to 1.6 mm wire running the length of a pipeline. The process, wire, gas, and transfer mode all change, but the principle has not moved since those late-1940s patents.

What This Guide Covers

This guide covers the process from arc formation and metal transfer through shielding gases, equipment, consumables, the four main transfer modes, common materials and industries, troubleshooting, and the safety and standards framework, and it compares MIG with TIG, stick, and flux-cored.

New to the process? Start with the transfer modes section, because understanding how metal moves from wire to puddle separates a welder who sets parameters from one who guesses. Already running MIG daily? The troubleshooting and comparison sections will give you more.

On scope: for any qualified weld, the AWS Z49.1 safety standard and the welding procedure specification are the documents that matter. A setting that works on one machine may not work on another, and the number on the machine is only the beginning of the story.

How the MIG Welding Process Works

MIG welding, or GMAW, joins metals by melting a continuously fed wire electrode with an electric arc. The arc creates a molten puddle, and as it cools, the filler wire fuses with the base metal to form a solid joint. As the TWI breakdown of the process shows, the defining advantage of MIG is that the electrode and filler are one consumable, allowing for fast, continuous welding.

Arc Formation and Polarity

The arc forms when the live wire tip touches the workpiece, completing a circuit and ionizing the gap into a plasma column that can reach between 10,000 and 20,000 degrees Fahrenheit. From there, polarity dictates where most of the heat goes.

DC+ (direct current reverse polarity) is the standard for most solid wire MIG work, putting more heat into the workpiece for better melting and less spatter. DC- (direct current straight polarity) shifts more heat into the wire, which can be useful for select aluminum alloys. For aluminum and magnesium, AC (alternating current) is often used to repeatedly break up the stubborn oxide layer on those metals. Many modern MIG machine setups use synergic modes to manage this automatically.

Constant Voltage and Machine Control

MIG power sources are primarily constant voltage (CV) units. Unlike a constant current (CC) setup, a CV machine holds voltage steady and lets amperage adjust on its own. If the arc shortens, current spikes and melts more wire to restore it. If the arc grows too long, the machine compensates to bring it back to the set voltage. This self-regulation is what allows for a stable arc with a continuously fed wire.

For solid wire, CV is the norm. For some flux-cored wires, arc characteristics differ enough that constant current (CC) can be better suited. Many machines offer a combined CV/CC mode or dedicated curves for solid and flux-cored wires, a distinction covered in our airgas welding equipment guide.

Wire Feed and Filler Metal

The wire feeder is just as important as the power source. It pushes the spool wire through a drive roll, down the liner, and out the torch to the copper contact tip. As it emerges, it carries current to sustain the arc and melts to become filler metal.

These wires are classified by AWS specifications. Common choices include ER70S-6 for mild steel, and ER4043 or ER5356 for aluminum. The right filler selection can be just as critical as machine settings, and our guide to all position welding rod types breaks down how these classifications work.

Shielding Gas

Without shielding, the molten puddle would react with oxygen and nitrogen in the air, leading to porosity and brittle weld metal. The shielding gas forms an invisible envelope around the arc, blocking the atmosphere while also helping transfer heat and metal droplets. Flow rates are typically set between 15 and 25 liters per minute for a standard shop torch. Too little invites contamination, and too much can create turbulence that pulls air back into the arc zone.

This principle applies to both inert and active gases, a difference outlined in the Fronius explanation of MIG and MAG welding.

Metal Transfer and Solidification

As the wire melts at the tip, droplets form and are transferred to the puddle by a combination of arc pressure, gravity, and electromagnetic pinch force. This transfer takes one of four main forms:

• Short circuit transfer: The wire touches the puddle and shorts, creating a current spike that melts a burst of wire. Ideal for thin material and out-of-position welding with low heat input.
• Globular transfer: Large droplets transfer one by one, often with more spatter and higher heat input.
• Spray transfer: A fine, continuous stream of small droplets is propelled into the puddle. This allows for high deposition rates and deep penetration with minimal spatter.
• Pulsed spray transfer: A pulsed current allows spray transfer at lower average heat inputs, making it possible to spray on thinner material without burn-through.

Once in the puddle, the molten metal mixes with the base metal and solidifies, fusing at the toes of the weld. Contaminants can ruin this bond, which is why steps such as proper aluminum cleaning and preparation are non-negotiable.

For accepted GMAW terminology and inspection requirements, the AWS codes and standards library remains the authoritative reference, specifically under AWS A3.0.

MIG vs MAG: Shielding Gases and Their Impact

Ohio shops say MIG. The same shop in Germany says GMAW, MAG, or “metal active gas.” The labels describe the same machine, the same continuously fed wire, and the same arc under the same AWS process classification. The only real difference is what comes out of the shielding gas cylinder.

MIG (metal inert gas) uses a gas that does not chemically react with the molten weld metal; MAG (metal active gas) uses one that does. In North America “MIG” became a generic word for the whole process, so most shops say MIG even when they run 75% argon and 25% CO₂ on mild steel, which is technically MAG. The family name that matches the gas is GMAW (Gas Metal Arc Welding), and TWI’s process overview frames it that way.

What “Inert” and “Active” Mean at the Arc

The shielding gas does three jobs at once: it keeps oxygen and nitrogen out of the molten pool, carries arc heat into the work, and changes how the wire behaves as it melts. “Inert” means the gas does not combine with the metal. Argon and helium are noble gases that leave the puddle essentially clean, which is why argon dominates aluminum, stainless steel, copper, and magnesium work, as covered in the Aluminum MIG Welding practical guide.

“Active” means the gas takes part in the metallurgy. CO₂ reacts with the weld metal, producing a faster, cooler-arc, higher-heat-input process with deep penetration and, unavoidably, more spatter. Active gases excel on carbon and low alloy steels, helping the puddle wet and flow into the joint.

The Four Gas Families

• Pure argon: The default for aluminum, stainless steel, copper, and magnesium. Excellent arc stability and minimal oxidation, but shallow penetration and a narrow, convex bead on carbon steel.
• Helium: Denser heat and a hotter, more stable arc than argon, raising heat input and penetration while allowing slower travel speeds. Costly, so it is usually blended, and it suits heated pipes and stainless overlays.
• Pure CO₂: Cheap and readily available. Deep penetration and high deposition on carbon steel, but it needs more voltage, makes noticeably more spatter, will not weld aluminum or magnesium, and often needs extra flow to displace air.
• Mixed gases: Ar/CO₂ blends of 75/25, 85/15, and 90/10 for steel; Ar/He blends of 75/25 and 50/50 for aluminum; and “tri-mix” (argon, helium, small CO₂) for stainless and carbon steel where you want a hot arc and a clean bead.

Gas handling is a safety topic, not a footnote. Cylinders are stored, chained, and regulated per AWS Z49.1, Safety in Welding and Cutting. Understanding regulators, flowmeters, and cylinder handling is worth the Air Gas Welding Explained primer.

How Gas Choice Changes the Weld You Get

Gas	Best base material	Penetration	Spatter	Typical transfer
100% argon	Aluminum, stainless, copper	Low in steel, good in aluminum	Low	Short circuit or globular in steel, spray in aluminum with the right wire
100% helium	Stainless, copper, high-alloy steel	High	Low	Spray
75/25 Ar + CO2	Carbon and low alloy steel	Medium to high	Low to moderate	Spray over a wide current range
85/15 or 90/10 Ar + CO2	Thin carbon steel, stainless	Moderate	Low	Short circuit to spray, easy on thin material
100% CO2	Carbon steel	Highest	Highest	Globular at production settings, short circuit for thin gauge
Ar + He blends	Aluminum, stainless	High	Low	Spray

Spray transfer gives you a wide, flat, well-penetrating bead with minimal cleanup. Pure CO₂ resists spray behavior, which is why most production shops moved to argon blends. Blended gas stabilizes the arc at lower amperage, so the same machine can run thinner material with less heat input, less distortion, and fewer repairs. Research on gas composition and metal transfer characteristics keeps quantifying these effects.

Argon wins on cleanliness: it leaves stainless welds bright and unpickled, keeps aluminum oxide from forming, and adds no carbon to the deposit. Helium is lighter than air and rises, so it needs a back purge on stainless to protect the root; argon is denser and stays put. CO₂ is heavier than air yet still needs roughly 15 to 20 CFM of flow versus about 10 to 15 CFM for argon, because it must push air away rather than let it fall in.

Quick Rules of Thumb

1. Carbon or low alloy steel: 75/25 argon-CO₂ is the default; switch to 85/15 or 90/10 for thin material and easy control.
2. Aluminum: 100% argon, or an argon-helium blend for thicker sections. Never CO₂. Start with the aluminum cleaning guide, since gas choice cannot rescue contaminated surfaces.
3. Stainless steel: 98% argon with 2% oxygen, or argon-helium. Tri-mix when welding stainless and carbon steel in the same job.
4. Outdoors or in a draft: shielding gas gets blown away regardless of blend, so plan for wind shields or move to a stick welding approach where flux does the shielding.
5. Unsure what to buy: talk through cylinder sizes, mixes, and delivery with a supplier such as AllGas Welding Supply before a bulk order.

Gas selection is the cheapest performance lever you have on a MIG machine. Get the shielding right first, then tune the machine.

Equipment, Consumables, and Setup Essentials

Weld quality in the MIG welding process is settled before the arc is struck. A well-tuned machine still performs poorly if the gun is worn, the contact tip is mismatched, or the gas flows at the wrong rate.

Power Sources: Choose the Current Control You Need

Most GMAW machines are constant-voltage (CV): the welder sets a voltage, the feeder pushes wire at a speed that burns it at roughly that voltage, and the machine supplies the current the arc demands. Wire feed speed largely sets amperage; voltage sets arc length and bead profile.

• CV: the MIG/MAG standard. Voltage is the primary knob, wire feed speed drives current.
• CC with arc voltage control: used with some flux-cored wire for a stable, low-heat arc.
• Pulsed MIG/MAG: high-frequency current pulsing for controlled transfer with less spatter; popular for stainless, aluminum, and thin-gauge work.
• Multi-process: one box for MIG, flux-cored, and sometimes TIG by swapping lead and torch.
• Duty cycle: shop-grade units running 40 volts and 300 amps often carry a 60 percent duty cycle at 100 percent output ratings.
• Output control: erratic voltage control makes a steady bead nearly impossible, so look for reactive or proportional response and inductive output smoothing.

Wire Feeders and the Welding Gun

• Push feeders: drive rolls sit in the gun body. Compact, but pushing a heavy spool down a long torch causes bird-nesting, so they pair with 4-inch (100 mm) spools of 0.030 or 0.035 inch wire.
• Pull feeders: drive rolls sit in the feeder body behind the spool, pulling wire through the gun. The production standard for larger wire diameters, handling 12-inch (300 mm) and 15-inch (380 mm) spools.

Drive rolls must be sized and knurled for the wire diameter; for aluminum they should be U-shaped or V-shaped with a serrated profile, since soft round wire slips on four-wheel straight rolls. Buy a decent trigger mechanism, since a worn trigger causes a sticky gun and uneven wire feed.

Modern MIG guns are push-style, with the feed rolls in the feeder, so they stay lighter than older push-pull designs that carried a second wire bundle.

• Contact tip: carries current to the wire and shapes it. Replace when the hole wears, elongates, or exceeds the wire diameter; for 0.035 and 0.045 inch (0.9 and 1.1 mm) wire the hole should be slightly smaller, since a loose fit makes the arc wander and wears the liner faster.
• Nozzle and gas diffuser: shape and distribute shielding gas; spatter fouling chokes gas flow and causes porosity.
• Liner: guides wire to the tip and must match wire diameter and gun length; worn liners cause friction and bird-nesting.

GMAW wire ranges from 0.6 mm to 1.6 mm: 0.6, 0.8, and 0.9 mm suit thin sheet, fine control, and all-position work; 1.0 and 1.2 mm are common mild steel production sizes; and 1.4 and 1.6 mm need a stronger machine and feeder and suit thicker plate, higher deposition rates, and long outdoor or shipyard jobs. Larger wire also demands more gas and often favors blends with more carbon dioxide. Nozzle size follows plate thickness and gas: small nozzles concentrate gas for thin material and short-arc work, larger ones for wider beads and heavier plate, and an oversized or porous nozzle on aluminum wastes argon.

Shielding Gas, Cylinders, and Regulators

Argon and argon/CO2 blends come in cylinders of roughly 300 or 400 cubic feet, with smaller sizes for portable work. A flowmeter on the regulator matters: a cylinder gauge alone is not enough, and a flowmeter also reveals restrictions or leaks downstream. Gas flow for most industrial GMAW work sits in the 25 to 35 CFH range, set by wire diameter, nozzle size, material, and position. Too little gas contaminates the weld and the result is porosity; too much creates a turbulent arc, wastes argon, and can lift molten metal into the nozzle.

Purge hoses before opening the cylinder, because a hose sitting open contains air and air in shielding gas is a leading cause of porosity on stainless and aluminum. Add a gas heater for cold-weather use, since liquid CO2 can ice up in the regulator and starve the arc. Use a cylinder cart with a chain or strap, and keep the regulator off the cylinder valve during transport. If you are still choosing a supplier, this overview of welding supply gases and services covers cylinder types and safety basics.

Work Clamps and Ground Connections

Every MIG job needs a path for current back to the source, and a poor ground causes erratic arc, spatter, and shock hazard if the workpiece is energized. Use a dedicated work clamp on clean, unpainted metal near the joint, never on dirty, rusted, painted, or oily surfaces, and keep it clear of the weld area so no stray arc path forms. For aluminum, clean the joint and clamp point with a dedicated aluminum prep cleaner, since oxide and trapped grease cause porosity and weak welds.

Consumable Classification: AWS Filler Metal Specs

Welding wire is not a generic product. It is classified to an AWS filler metal specification, which states mechanical properties, the shielding gas it is designed for, and approved positions. Wire approved for flat and horizontal work is not automatically approved for vertical or overhead.

• AWS A5.18: carbon steel electrodes, covering E70S-6 solid wire for CO2 and E71T-1 flux-cored wire.
• AWS A5.9: stainless and heat-resisting steel, including E308L and E316L, with the “L” denoting low carbon for better weldability.
• AWS A5.20: aluminum and aluminum alloys, including ER4043 and ER5356. ER5356 contains a small amount of magnesium, making it the usual choice for higher-strength aluminum and aluminum MIG work in general, while ER4043 is the filler most often used for aluminum boat hull repairs.
• AWS A5.14: copper and copper alloys.

Match the filler metal, diameter, and shielding gas to the base metal and to the process code on your welding procedure specification (WPS).

A Pre-Weld Setup Checklist

1. Confirm CV mode and polarity (DCEP for most solid wires, DCEN for aluminum and copper).
2. Verify the contact tip matches the wire and the nozzle is spatter-free.
3. Check liner diameter, liner length, and the gun cable for sharp bends.
4. Set gas flow in the 25 to 35 CFH range and check connections for leaks with soapy water.
5. Confirm the work clamp sits on clean metal with a solid electrical path, and purge the gun on stainless and aluminum.
6. Set wire feed speed and voltage per your WPS, then run a bead on scrap of the same thickness.

For the process itself, the Fronius guide to MIG/MAG welding covers the arc, wire feed, and shielding in detail, and the ESAB beginner’s guide to MIG welding is a good companion read for setup fundamentals. Good equipment is the foundation, but the real skill is knowing which mode, gas, and wire to reach for, which is where the next section on metal transfer modes comes in.

Metal Transfer Modes and Their Applications

The same MIG machine, wire, and gas can behave like four different processes, and what separates them is not the settings on the box but how molten metal moves from the wire tip to the puddle. That is metal transfer mode, and it decides bead shape, spatter, penetration, and how the gun is held. TWI’s guide to MIG welding frames it the same way, and modern power sources are built for controlled access to each mode.

Short Circuit Transfer (Short Arc)

Short circuiting is the default on nearly every MIG machine. The wire feeds into the arc, touches or nearly touches the puddle, current spikes, the wire melts at the contact, and the arc re-forms, hundreds of times per second. That rapid cycle keeps heat input low and the puddle small, which is why the mode suits thin material, small-diameter wire, and heat-sensitive work. It is also the easiest mode to run by hand, which makes it the best training ground for a new welder.

• Heat input: Low. Ideal for thin sections and low distortion.
• Positions: All, including vertical and overhead.
• Spatter: Moderate, rising with voltage. Irregular droplets signal a drift toward globular transfer.
• Typical use: Sheet metal, auto body work, thin-wall tubing, stainless trim.

Globular Transfer

Globular transfer sits between short circuiting and spray. The wire melts into large droplets that detach and fall into the puddle under gravity and arc force. Because large droplets need more heat to build, the tip runs hotter and the arc stretches longer than in short circuiting, giving more spatter as hard little balls, a harder-to-control puddle, and an erratic, lumpy bead.

Operators avoid this mode except for one job: welding aluminum with a spray gun, where aluminum’s high thermal conductivity and tendency to ball up make large-droplet transfer useful. Aluminum-specific guns with large contact tips and knurled drive rollers make that predictable, and our aluminum MIG welding guide notes that most aluminum MIG work today runs in spray or pulsed spray.

Spray Transfer (Full Spray)

Spray transfer is the high-production mode. The wire melts continuously and droplets detach while the arc is still short, arriving as fine droplets smaller than the wire diameter with enough momentum to lay a smooth, flat bead with minimal spatter and deep penetration. You get high deposition rate, high travel speed, and a bead that needs almost no cleanup.

• Heat input: High for a given wire diameter, with a hotter, more stable arc.
• Positions: Flat and horizontal only. Vertical and overhead pools are too fluid to control.
• Spatter: Minimal when parameters are right. “Spatter creep,” where fine particles land on the hot piece and oxidize into a hard, gritty film, is the usual culprit.
• Typical use: Heavy structural steel, pressure vessel and pipe work, thick aluminum.

Spray needs wire of 0.045 in (1.2 mm) and up, a machine rated 300 amps or more, and a supporting gas. Argon-rich mixes such as 90% argon and 10% CO2 are standard on steel because the higher argon content improves wetting, arc stability, and spatter control. On aluminum, read our guide to cleaning aluminum before welding first, since a contaminated plate undermines a perfect setup.

Pulsed Spray Transfer

Pulsed GMAW solves a simple problem: spray and short circuiting each give you something you want and something you don’t. The machine switches current rapidly between a high peak and a lower background value, modulating wire feed speed in sync with the current. The result is controlled droplet transfer that behaves like spray but dumps far less heat into the joint, which is why pulsed works in positions straight spray cannot handle and suits thinner and heat-sensitive material.

• Heat input: Precisely controlled. The peak stage melts the wire and drives the droplet off; the background stage cools the puddle and limits burn-through.
• Positions: All, including vertical and overhead, and on pipe in all orientations.
• Spatter: Very low. One of the cleanest beads of any GMAW mode.
• Typical use: Automotive and trailer manufacturing, stainless food and process equipment, thin-gauge aluminum.

On aluminum, pulsed MIG is the default in many production shops because it handles the alloy’s heat sensitivity without the sluggishness of short circuiting. It rewards good setup: clean the oxide, use the correct spool gun or push-pull feeder, and confirm the gun is set for the wire diameter. Our guide to how aluminum flux welding works covers another route to controlling heat on aluminum, and the complete aluminum flux core welding overview helps if you are weighing FCAW against pulsed GMAW for thick aluminum sections.

Side-by-Side Comparison

Mode	Heat Input	Positions	Spatter	Best For
Short circuit	Low	All	Moderate	Thin material, all-position work, training
Globular	Medium	Flat, horizontal	High	Mostly aluminum with a spray gun, troubleshooting
Spray	High	Flat, horizontal	Low	Heavy plate, structural steel, high production
Pulsed spray	Controlled	All	Very low	Production work, stainless, thin or heat-sensitive alloys

Choosing the Right Mode

1. Start with thickness. Under about 1/8 inch (3 mm), short circuit. Between 1/8 and 1/4 inch, short circuit or pulsed, depending on how much heat the alloy tolerates. Over 1/4 inch, spray.
2. Then check position. Vertical or overhead means short circuit or pulsed in carbon steel. Straight spray is off the table.
3. Then consider alloy. Aluminum and copper are heat-sensitive, pushing you toward pulsed. Stainless benefits from pulsed because it limits distortion and sensitization.
4. Then consider volume. One-off repairs favor short circuit for control. A run of a thousand brackets favors pulsed or spray for speed and consistency.

One more variable deserves attention: heat input. The relationship is circular, because a mode that deposits more metal per unit length needs more energy at the joint, and more energy means more distortion and a higher cracking risk in high-strength or stainless alloys. Pulsing exists to break that link. Standards such as AWS WHS Chapter 1.9 on welding safety and the broader AWS framework at the AWS standards directory are where you confirm heat input and preheat limits for a regulated job.

Adjust by ear and eye: a harsh crackle means a cold, tight short circuit arc, a steady buzz with a flat, wide bead means spray, and a sputtering mess means you are sitting in the unstable middle.

Materials, Applications, and Capabilities

One of the biggest reasons MIG welding became the default joining process in so many shops is that it covers an enormous range of materials. The same machine, with different wire, gas, and parameter settings, runs from a 3 mm sheet-metal lap joint on a car door to a structural fillet weld on a pressure vessel. GMAW accounts for more than 50% of all weld metal deposited across industry, according to process usage data compiled by the American Welding Society (AWS) and equipment manufacturers. Versatile, however, is not the same as universal.

Carbon Steel and Low-Alloy Steels

Carbon steel is MIG’s home turf: inexpensive, forgiving, and forgiving of a wide window of usable parameters. Solid ER70S-6 wire with 75% argon and 25% CO₂ (C25) is the general-purpose workhorse, and ESAB’s beginner’s guide to MIG welding notes that this blend balances penetration, bead profile, and spatter control on mild steel. For heavier structural work, an 80/20 blend or straight CO₂ raises deposition rate and heat input, though spatter and arc noise go up. Carbon steel is also where short-circuit and spray transfer modes both shine, which is why MIG dominates shop fabrication, structural steel erection, and general repair.

Low-alloy grades such as chrome-moly and nickel-bearing steels weld fine with the right wire and preheat, but they add heat-input control and hydrogen cracking to the picture, so many codes still call for SMAW or FCAW. For a side-by-side reference on alloy steel welding electrode selection and safety, that is a good look at the stick process MIG is often measured against.

Stainless Steel

Stainless MIG is about protecting the weld. Austenitic stainlesses (304, 316) are routinely welded with ER308L wire and a tri-mix of roughly 90% argon, 5% helium, and 5% CO₂, or a simpler 98% argon / 2% CO₂. The argon-rich blend improves hot-crack resistance, keeps the bead clean, and limits nitrogen and carbon pickup from the air. Stainless also conducts heat differently from carbon steel, so the puddle pulls heat away faster and travel beads need more dwell than you would expect. Expect heat tint as well: cosmetic on most work, but a rejection criterion on food-grade, pharmaceutical, and decorative fabrication. Modest heat input, cleaning between passes, and back-side purge gas where required all help.

Aluminum and Aluminum Alloys

Aluminum is where MIG’s easy reputation breaks down. It conducts heat roughly five times better than steel, so the puddle races ahead of the arc, and its higher thermal expansion rate and stubborn oxide layer must be dealt with before welding. Even so, the process suits the material well: solid ER4043 and ER5356 wires deposit quickly, and a MIG gun is lighter and easier to control than a stick holder. The challenge is feeding.

• Spool-gun or push-pull feeding is the go-to solution. Aluminum wire is soft and kinks easily, so a standard feeder can buckle it inside the liner. Push-pull guns add a second, smaller liner so the wire is pushed as well as dragged.
• Big contact tips and bigger liners are non-negotiable. A 3/32 inch contact tip with a matching liner is a common starting point for 0.035 and 0.045 inch aluminum wire.
• Pure argon shielding is standard. Active gases can create porosity or attack the oxide film, while a small helium addition gives a more stable puddle with better penetration.

Prep matters as much as machine settings. Removing mill scale, grease, and oxide with a dedicated welding aluminum cleaner, brushing the joint only with a stainless wire brush, and cleaning immediately before welding separates a sound weld from a porous one. Our complete practical guide to aluminum MIG welding goes deeper on wire, gas flow, torch technique, and feeding problems, and on thicker aluminum it is worth comparing MIG with aluminum flux core welding, which cuts cleanup but limits positional control.

Aluminum shows up constantly in transportation work: boat hulls and decks in our aluminum boat welding guide, and wheels and chassis parts in the alloy wheel welding guide.

Copper, Nickel, and Other Alloys

Copper and copper alloys weld with MIG but are demanding. Copper’s very high thermal conductivity pulls heat away from the puddle, which tends to freeze at the edges, so expect preheat on heavy sections, pulsed or spray transfer, and consistent travel speed. Beryllium copper and bronzes are commonly TIG-welded instead, where crack resistance or contamination control matters. Nickel alloys such as Inconel 625 and Hastelloy can be GMAW’d with matching filler and pure argon, though they need meticulous wire handling and many aerospace applications default to TIG. Titanium is similar: contamination control and sealed-chamber inert shielding keep MIG uncommon outside specialized high-volume production. Our aerospace welding guide covers that demanding field in more depth.

Where MIG Welding Gets Used Every Day

Where a welder needs volume, repeatability, and minimal cleanup, MIG wins.

Industry	Typical MIG Work	Why It Fits
Automotive and transportation	Body panels, exhaust parts, chassis brackets, alloy wheels	Thin gauge, fast cycle times, robotic repeatability
General fabrication and job shops	Frames, handrails, sheet metal enclosures, machine bases	All-position work, easy cleanup, minimal equipment
Shipbuilding and marine	Aluminum superstructure, steel hull sections, pipe and railings	Long seams, structural and non-structural hull work
Aerospace	Aluminum and sheet metal assemblies, ground support structures	Tight tolerances, certification discipline
Pressure equipment and energy	Skids, tanks, pipe spools, structural supports	Deposition rate in flat and horizontal positions
Agriculture and heavy equipment	Repair and modification of implements, frames, wear parts	Field friendly, wide material range, easy training

Two capabilities tie much of this together. The first is mechanization and robotic automation. Because GMAW is a constant-voltage process with continuously fed wire, it maps cleanly onto automated cells: a robotic MIG station holds consistent travel speed, stick-out, and torch angle across thousands of repeat welds, which is exactly what automotive and structural lines need. Fixture design and joint tracking become the limiting factors rather than welder stamina. The alpha laser welding systems guide shows where a newer non-contact process is pushing into the same space.

The second is field deployment. A MIG machine that runs off a generator, a cylinder of shielding gas, and reliable power can go to a bridge, shipyard, or farm field, and many marine welding operations and repair shops depend on that flexibility.

Choosing the Right Process for the Job

Material capability is only half the equation, and the honest answer is that MIG does not win every job. Steel plate thicker than roughly an inch in a position other than flat or horizontal often goes to flux-cored or submerged arc for deposition rate. Work demanding control over a visible finished bead, or very thin material, frequently favors TIG. And outdoor jobs where gas is unavailable or logistics get difficult still favor stick, a point made in why SMAW still wins in many scenarios. For general-purpose shop and field welding across carbon steel, stainless, and aluminum, though, MIG stays hard to beat on speed, control, and its modest learning curve. Matching wire, gas, and transfer mode to the material is the whole game, and the sections on transfer modes and gas selection go deeper into how that choice is made.

Common Mistakes, Defects, Troubleshooting, and Solutions

Welding rarely fails for dramatic reasons. It fails quietly: a bead that looks fine but is porous underneath, a joint that separates the moment it loads. Nearly every MIG defect traces back to a few physical causes, and reading the symptoms turns diagnosis from guesswork into routine.

Porosity: The Number One MIG Defect

Gas pockets trapped in the weld metal: a rough, cratered surface that looks like a sponge once you cut the bead open. On pressure vessels or structural joints, it means rejection.

Three root causes cover nearly all porosity:

1. Inadequate shielding. Drafts, an open door, a fan aimed the wrong way, or too little flow let oxygen and nitrogen attack the pool. Too much flow is a separate fault: it entrains air and leaves a rough, wide bead with heavy spatter.
2. Contaminated base or filler metal. Paint, rust, oil, grease, moisture, and cutting fluid burn off as gas. Aluminium is extra sensitive, since its fast-forming oxide holds moisture; see our guide to cleaning aluminium correctly before welding.
3. Gas flow and moisture in the gas. A nearly empty cylinder, a regulator set too low, a leaking hose, or a gas line contaminated from other work starves the shield.

The fix: Clean the joint with a dedicated stainless or carbon steel prep tool and clean, dry wire, clear spatter from the nozzle tip, and set flow for the material and position. Training from ESAB treats gas flow and surface cleanliness as the first two checks when porosity appears.

Lack of Fusion: Cold Joints That Will Not Bond

Weld metal that fails to melt into the base metal. The bead looks rounded and convex, sitting on the surface, and a grinder finds unfused metal at the toe.

• Insufficient heat input. Arc too fast, or voltage and amperage too low; cutting wire feed to tame spatter also cuts heat.
• Poor joint prep. Narrow groove angle, oversized root face, or a gap the puddle cannot bridge.
• Contaminated surfaces. Mill scale, rust, and oxides form a barrier the filler cannot wet into.
• Wrong travel angle or position. Pulling the torch so the arc points away leaves the puddle travelling uphill to the sidewall.

The fix: Prep the joint first, then add heat: slower travel, higher amperage, or a small voltage increase with matching wire feed, holding a 10 to 20 degree drag angle. Aluminium needs more heat than steel, hence its dedicated MIG guide.

Burn-Through and Undercut

Burn-through melts through the metal, leaving a hole or wide molten crater. Undercut is a groove along the bead toe where the arc gouged the base metal. Both erode joint thickness, and both are fatigue-critical.

Burn-through on thin material is a heat input problem: too much amperage, too slow a travel speed, or too much dwell while positioning. Reduce amperage, use a smaller diameter wire, speed up travel, and hold the gun higher with a small weave rather than dwelling.

Undercut is usually technique: the arc held too low or too wide, or an excessive travel angle, so it cuts ahead of the puddle. Bring the gun angle back toward 10 to 15 degrees, keep the arc length short, and check the contact tip is not recessed into the nozzle. On a repair rather than new stock, joint design matters as much as technique: reinforcing pads and heavier sections cut the heat concentration that causes gouging.

Spatter: Too Much of It

Globules of metal ejecting from the arc and landing around the joint. Some is normal; a great deal signals a parameter or consumable problem.

The classic cause is mixed transfer mode: the wire feeds into the puddle faster than it can melt and the arc is too long, often in short-circuit transfer with voltage high or wire feed low for the current. Raise wire feed to match amperage and drop voltage until the arc crackles evenly rather than popping. A visible gap between contact tip and work means the arc is too long.

• Wrong polarity. DCEP on a material suited to DCEN changes the heat balance and raises spatter.
• Worn contact tip or drive rolls. A damaged tip creates an erratic arc that spits.
• Wrong shielding gas. Pure CO2 produces more spatter than an argon mix, while heavier gases such as helium reduce it. Spatter-busting copper wire helps with CO2, but an argon-based shielding gas mix suited to the material is the better answer.

Wire Feeding Problems

Wire that will not feed makes the arc sputter and cut out; wire that feeds too fast runs the torch away; wire that wanders makes the bead zigzag.

Component	Symptom	Action
Liner	Wire drags, kinks, or stops at inconsistent points	Replace a worn, grooved, or contaminated liner. Match liner ID to wire diameter.
Contact tip	Arc spits, wire stalls at the tip	Replace the tip and match the ID to the wire size; a mismatched tip is a leading cause of feeding problems.
Drive rolls	Wire slips or feeds unevenly	Clean or replace grooved rolls. Check for flattened knurling on V-grooved rolls.
Tension setting	Wire feeds but does not retract, or retracts but does not feed	Adjust so the wire feeds on the drive roll under light finger pressure, no more.

Diagnostic: wire that feeds freely with the feeder disconnected but stalls in the gun points to the liner or contact tip; stalling with the gun removed points to drive roll tension or the feeder. Check torch polarity too, and that the liner is seated fully, since a kinked liner stutters at the same point every time.

Shielding Gas Problems

Gas faults imitate everything else: a dull, oxidised bead, a wider arc than expected, and porosity that will not go away. Work through this sequence before changing machine settings.

1. Cylinder level and correct gas installed.
2. Regulator set for the nozzle size in use.
3. Hose leaks at fittings and flex points.
4. Blocked gas diffuser or spatter-packed nozzle.
5. Hose shared with another process: an oxygen or cutting gas line is a hazard as well as a quality problem.

Long gun leads can starve the nozzle. If the flow meter reads correct at the machine but the bead is still starved, look for a restriction or leak between the feeder and the gun.

The Routine That Prevents Most of This

A short routine prevents most defects:

• Inspect gun, tip, and nozzle before every job or shift.
• Verify gas flow and cylinder condition.
• Clean the joint and confirm fit-up.
• Run a test coupon on new setups, wire, or gas mix.
• Record the settings that worked.

None of this is glamorous, but it is the difference between a weld that passes inspection and one that gets cut out. Learn the symptoms, work the checklist, and troubleshooting in the MIG welding process stops being a crisis.

Safety, Standards, and Best Practices

With the speed and versatility of the MIG welding process comes a level of responsibility that can never be overlooked. No matter how experienced a welder becomes, the work environment presents constant hazards that require discipline to avoid. By following proven safety practices and industry standards, these risks can be drastically reduced without sacrificing productivity.

Welding Fume Hazards

One of the most overlooked dangers of MIG welding is the smoke itself. The process produces welding fumes that contain fine metallic particles, and depending on the base metal and filler wire, these can be far more hazardous than they appear. Welding galvanized steel, stainless steel, or certain aluminum alloys can release especially concerning compounds into the air. For example, welders working on structural repairs or aluminum boat welding projects must pay extra attention to what they’re breathing. Long-term exposure without protection can lead to serious respiratory issues, making fume control a necessity, not an option.

Electrical Safety

MIG equipment runs off high-amperage electricity, leaving little room for carelessness. Faulty cables, damaged insulation, or a poorly grounded work clamp can all create the risk of electric shock. Before striking any arc, connections should be inspected for fraying or loose fittings. It’s also imperative to keep hands, gloves, and work areas dry, as moisture is one of the quickest ways to increase that risk. Never attempt to repair live power components, and always de-energize equipment before any maintenance is performed.

Fire Prevention

Sparks and molten metal can travel much farther than most people realize. A stray spark can easily ignite rags, flammable liquids, or even dust in a shop. Before beginning work, the surrounding area should be cleared of combustibles, and a fire extinguisher rated for electrical and metal fires should be within arm’s reach. Extra caution should be taken in tight fabrication areas, especially when completing cosmetic repairs such as alloy wheel welding, where nearby tires, rubber, or sealants can become extreme fire hazards.

Personal Protective Equipment (PPE)

Welders must use appropriate PPE including auto-darkening helmets, flame-resistant clothing, and suitable gloves. A properly rated welding helmet protects against intense UV and IR radiation that can cause “arc eye”, while untreated clothing can ignite from a single spark. Gloves should be selected specifically for MIG work to allow dexterity without sacrificing heat resistance. Closed-toe, leather work boots with non-slip soles are also required to protect against falling spatter and heavy parts. For shops that frequently source their gear from suppliers like Airgas welding supplies, ensuring each piece meets its intended rating is just as important as having it on hand.

Ventilation and Confined Spaces

Not all shops are created equal, and neither are all welding jobs. Working inside tanks, trailers, or other tight enclosures drastically limits air movement, allowing fumes to build up at dangerous concentrations. When ventilation is insufficient, a source capture fume extractor should be utilized, and in some scenarios, respiratory protection may be required. Before entering any confined space for welding, a proper assessment for toxic atmospheres must be completed. This is especially vital for specialty applications such as aluminum MIG welding, where fume composition can change greatly between base metals.

Key Standards and Best Practices

Safety isn’t based off of guesswork. ANSI Z49.1 provides comprehensive safety guidance for welding, cutting, and allied processes, acting as the backbone for shop safety programs across North America. Alongside this, AWS A3.0 establishes standardized welding terminology to ensure hazards and procedures are clearly communicated. These are reinforced by applicable OSHA guidance, as well as the wide range of codes and publications found through the AWS standards and publications library.

With all of these in mind, the most effective approach is consistency. Inspect equipment daily, control your fumes, dress for the arc, prevent fire, respect electricity, and stay up to date with the standards for your work. These practices may seem tedious at times, but they are the difference between a long career of quality welds, and one cut short by a preventable accident.

Practical Tips, Comparisons, and When to Choose MIG

Knowing how the MIG welding process works is only half the battle. The real skill comes from knowing when to reach for a MIG gun, when to set it down, and how to dial in parameters for consistent, quality results. Whether you’re just getting started or looking to refine your technique, a few practical guidelines can go a long way.

MIG vs. Other Welding Processes: A Quick Comparison

While MIG (GMAW) is incredibly versatile, it’s not always the right tool for the job. Understanding its strengths and weaknesses against other common processes is key to choosing wisely.

Factor	MIG (GMAW)	TIG (GTAW)	Stick (SMAW)	Flux-Cored (FCAW)
Ease of Learning	Easy to moderate – very beginner friendly	Difficult – requires hand coordination	Moderate – technique sensitive	Easy to moderate
Deposition Rate	High	Low	Moderate	Very high
Outdoor/Windy Use	Poor – needs clean, still air for shielding	Poor – very sensitive to drafts	Good – flux coating provides shielding	Very good – self-shielded FCAW excels in wind
Weld Appearance	Clean with minimal cleanup	Very clean, precise, aesthetic	Rougher, requires slag removal	Rougher than MIG, slag removal may be needed

In most shop environments, MIG is generally easier to learn than TIG and offers higher deposition rates than SMAW for many applications. However, for outdoor or windy conditions, flux-cored arc welding may be more suitable than GMAW due to shielding limitations. If you need extreme precision on thin materials or exotic metals, TIG may still be the better choice.

Tips for Beginners and Experienced Welders

No matter your skill level, dialing in consistency comes down to preparation, parameters, and quality control. Keep these actionable tips in mind:

• Prep is non-negotiable: Clean mill scale, oil, rust, and oxidation from your base metal. For aluminum specifically, proper degreasing and oxide removal is critical – see resources like aluminum cleaner for welding to avoid contamination related defects.
• Start with recommended parameters: Use the voltage/wire speed chart for your wire, gas, and material thickness as a starting point, then fine-tune. Referencing guidance from ESAB’s beginner guidance can help establish a baseline.
• Mind your travel speed and stickout: A consistent contact tip to work distance (usually 3/8″ to 1/2″) and steady travel speed prevents burn-through, lack of fusion, and excessive spatter.
• Consider advanced modes when needed: Synergic/pulse technologies have expanded MIG capabilities for positional and thin material welding. If your machine has pulsed spray, use it for out-of-position work or heat sensitive alloys to minimize distortion.
• Practice quality control: Inspect your welds for consistent bead profile, proper fusion, and absence of porosity. For critical work, follow standards-based practices from resources like AWS Codes and Standards.

When to Choose MIG Over the Rest

With all this in mind, MIG shines in specific scenarios. Choose it when:

• Speed matters: For long seams or high production work, MIG’s continuous wire feed drastically outpaces TIG.
• You need a clean shop-friendly weld: With the right gas mix, MIG produces minimal slag and relatively little spatter, reducing post-weld cleanup.
• You’re working in a controlled environment: If you’re in a shop free from strong drafts, GMAW is hard to beat for carbon steel, stainless, and many aluminum applications.
• You want versatility: With the ability to switch transfer modes, wire types, and gas mixes, a single MIG setup can tackle a wide range of thicknesses and materials.

On the flip side, skip MIG in favor of FCAW or SMAW for heavy outdoor fabrication, and opt for TIG when aesthetics or precision on ultra-thin, critical joints are the priority. By weighing these factors against your project constraints, you’ll be able to confidently choose the process that strikes the right balance between speed, quality, and practicality.

Conclusion: Mastering the MIG Welding Process

Metal Inert Gas welding grew from a single goal: shield the weld from the atmosphere. Continuous wire feed, a stable arc, and a protective gas blanket mean less spatter to clean, fewer passes, and faster tacks between fitting pieces. The same equipment handles carbon steel, stainless, aluminum, and copper, which is why MIG became the dominant arc welding process by weld metal deposited and the process most shops reach for first.

Speed is only half the equation. A fast weld that is porous, cracked, or lacking fusion is a repair waiting to happen. The gap between mediocre and excellent MIG work is rarely a secret technique. It comes down to consistent decisions: right shielding gas, a transfer mode matched to the joint and position, parameters that balance penetration against heat input, and safety habits that protect everyone nearby.

Four Things That Decide Weld Quality

MIG is a system, not a single setting. Change one variable and the others need attention too.

• Gas selection shapes the whole process. Inert gases like argon and helium suit aluminum and stainless. Active gases like CO2 and argon-CO2 mixes deposit faster and penetrate deeper on steel but spatter more. Helium blends are the usual compromise on thicker material.
• Transfer mode matters more than amperage. Short circuiting suits thin sheet and out-of-position work, spray suits flat, heavy mild steel, and pulsed spray gives a controlled, low-spatter arc where position and appearance matter.
• Parameters must suit the material and thickness. Wire diameter, feed speed, travel speed, shielding gas, and stickout work together. Wire too thin for the amperage or travel speed too slow gives burn-through and distortion; too fast and you get undercut.
• Surface condition is a parameter too. Paint, rust, oil, and moisture undermine the arc. Aluminum demands careful cleaning, so a dedicated aluminum cleaner for welding guide is worth reading before repairs on castings or wheels.

Choose the Right Process, Not Just the Familiar One

MIG is excellent, but there are jobs it should not take. Thin stainless or reactive alloys call for TIG, where heat input is controlled bead by bead. Heavy structural steel and outdoor field work, where wind scatters shielding gas, are classic advantages of stick welding territory. Flux-cored wire handles rust and thick plate without a gas bottle, and aluminum work often pairs MIG with flux-core for messy joints. Our complete aluminum MIG welding guide covers polarity, purging, and filler selection. Choosing another process is not a rejection of MIG; it is the fastest route to a good weld.

Safety Is a Standard, Not an Option

Welding fume can contain serious metal compounds, and shielding gases add their own hazards. That is why AWS Z49.1, Safety in Welding and Cutting and Allied Processes and AWS A3.0M exist, alongside OSHA guidance on fume control and hot work. Respecting them is not paperwork; it is why you can keep welding for a career instead of a few months.

Ventilation, properly fitted PPE including a helmet, cylinder and regulator checks, fire watch discipline, and electrical awareness form the baseline. ANSI’s overview of the Z49.1 standard is a good reference when setting up shop or jobsite policy.

Keep Learning, Keep Records

No experienced MIG welder stops finding something new. Filler classifications change, wire specifications get revised, and gas blends get refined. Staying current with AWS codes and standards and with practical resources like TWI’s job knowledge on MIG welding keeps your work consistent and your qualifications current.

Write down your settings when a job goes well: wire size, gas, amperage, voltage, feed speed, and travel speed. Next time the same joint appears, you are not guessing again. Over a year, that habit becomes a process sheet, and a process sheet separates a shop that quotes jobs accurately from one that learns the hard way.

The Takeaway

MIG rewards preparation and punishes guesswork. Get the gas right, match the transfer mode to the job, clean the metal, set sensible parameters, and follow the safety standards, and you get something rare: fast welds that are also good welds. The process is forgiving enough to learn quickly and demanding enough to reward those who keep refining their craft, which is why mastering MIG is worth the effort.

Start with the fundamentals and build from there. An aluminium welding course overview shows what training options exist and what they cover.

Frequently Asked Questions

What is the difference between MIG and GMAW?

MIG (Metal Inert Gas) welding is the common name for Gas Metal Arc Welding (GMAW) as defined by AWS. In many texts, MIG refers to GMAW with inert shielding gases, while MAG refers to active gases, though the equipment and process are essentially the same.

What gases are used for MIG welding?

For true MIG (inert gas), argon or helium is used, often for aluminum and non-ferrous metals. For MAG (active gas), CO2 or argon/CO2 mixtures are used for carbon and low alloy steels. The choice depends on material and desired weld characteristics.

Is MIG welding good for beginners?

Yes, MIG welding is often considered one of the easier arc welding processes to learn due to its continuously fed wire and relatively forgiving nature with short circuit transfer. However, proper setup, shielding, and safety still require training and practice.

What metals can be welded with MIG?

MIG/MAG can weld carbon steel, stainless steel, aluminum, copper, and many alloys. The correct wire electrode, shielding gas, and transfer mode must be matched to the base material for optimal results.

What is the difference between MIG and TIG welding?

MIG uses a continuously fed consumable wire electrode with shielding gas through the gun, making it faster for many applications. TIG uses a non-consumable tungsten electrode and often a separate filler rod, offering more precise control but typically at slower speeds.

What safety gear is needed for MIG welding?

Essential PPE includes a welding helmet with proper shade (per ANSI/AWS guidance), flame-resistant clothing, leather welding gloves, and safety footwear. Adequate ventilation or fume extraction is also critical to avoid exposure to welding fumes.

What is pulsed MIG welding?

Pulsed MIG (pulsed GMAW) uses a pulsed current waveform to control heat input and droplet transfer. This allows for better positional welding, reduced spatter, and improved control when welding thinner materials or heat-sensitive alloys.

Why does MIG welding produce porosity?

Porosity is usually caused by insufficient or disrupted shielding gas (leaks, wind/drafts, low flow), contaminated base metal (oil, rust, moisture), or improper gun angle. Ensuring clean surfaces, proper gas coverage, and draft protection helps prevent it.

Can MIG welding be used outdoors?

MIG welding is sensitive to wind and drafts because they can blow away the shielding gas. For outdoor use, wind screens are often necessary, or flux-cored welding (FCAW) may be a better alternative since it provides its own slag/flux shielding.

What power source is used for MIG welding?

Most MIG welding uses a constant voltage (CV) power source. This allows the arc length to be self-adjusting as wire feed speed is set, providing stable and consistent welding conditions for the operator.