Which Welding Processes Normally Use a Constant Current Power Source? SMAW, TIG & More Explained

Marcus had been MIG welding on his shop’s constant voltage machine for years, so when he borrowed an old stick welder for a repair job, he did what came naturally: he looked for the voltage dial. It wasn’t there. Instead, the machine had nothing but an amperage selector and a cranky arc that seemed to fight him. That frustrating afternoon is exactly why the question ‘which welding processes normally use a constant current power source?’ matters so much, because plugging the wrong process into the wrong machine is one of the fastest ways to ruin a weld, and one of the easiest mistakes to avoid once you understand the electrical logic behind it.

Introduction: The Voltage Dial That Wasn’t There

Marcus had been MIG welding on his shop’s constant voltage machine for years, so when he borrowed an old stick welder for a repair job, he did what came naturally: he reached for the voltage dial. It wasn’t there. The machine had nothing but an amperage selector and a cranky arc that fought him all afternoon. If that scene feels familiar, you’re in good company. That missing dial is where most welders first bump into the question at the heart of this article: which welding processes normally use a constant current power source?

It’s a fair question, and a practical one. Most people searching for this answer aren’t curious about electrical theory for its own sake. They’re trying to match a process to a machine they already own, or one they’re about to buy, and they want to avoid burning through a workpiece learning the hard way.

What “Normally” Actually Means

Welding language is full of words that sound absolute but aren’t, and “normally CC” is one of them. Here’s the distinction that will keep you out of trouble:

• Normally CC means the process is designed around, and practically unusable without, a constant current output. Stick and TIG live here. The whole technique depends on it.
• Can run CC in specific setups means the process usually runs constant voltage but has configurations where CC makes sense. Submerged arc welding (SAW) with a voltage-sensing wire feeder, or GMAW on high-conductivity metals like aluminum, fall into this category.

Why the difference? Because a constant current machine varies its output voltage to maintain a steady current, while a constant voltage machine fluctuates its output current to maintain a set voltage. That one sentence decides which processes get an amperage dial and which get a voltage dial. Everything else in this article follows from it.

The real-world stakes are simple. Weld on the wrong power source type and you get an unstable arc, poor penetration, or a hole where your bead should be. Marcus’s frustrating afternoon wasn’t a skill problem; it was a machine-process mismatch, and those are the cheapest mistakes in welding once you understand the logic.

Why Arc Length Control Decides Everything

Underneath the CC-versus-CV split sits one governing principle: who controls arc length. If a human hand holds the electrode, the machine needs to hand that person a steady, predictable current no matter how much the arc distance wobbles. That’s constant current. If a wire feeder holds the arc by pushing metal in at a fixed speed, the machine needs a self-correcting voltage to keep things balanced. That’s constant voltage. It isn’t tradition or habit; it’s heat input physics.

And yes, it matters whether you’re a hobbyist running your first bead or a pipe welder working to a written procedure. Match the process to the right power source and the arc becomes forgiving. Mismatch them, and no amount of technique will save the weld.

What This Guide Covers

We’ll start with the electrical foundation by reading the volt-ampere curve without needing an engineering degree. Then we’ll give you the direct list of constant current processes with justifications, dig into stick and TIG as the two flagship CC applications, and widen out to overlooked CC niches like carbon arc gouging. After that comes the other half of the story, when constant voltage takes over with MIG and flux-cored, followed by hands-on setup, the mistakes that ruin CC welds, and a decision rule you’ll remember for good.

New to welding altogether? Start with our honest beginner’s guide to stick welding, which walks through the learning curve before you get deep into power source theory. And when you’re ready for the CV side of the house, our complete MIG welder setup guide covers the machines where voltage, not amperage, is the dial you’ll be turning.

One last thing: safety follows the same logic as the arc. Wrong machine settings create fumes, spatter, and flash risks long before they create a bad weld, so keep our complete welding PPE guide within arm’s reach.

Let’s start where every good weld does, at the arc itself.

Constant Current vs Constant Voltage: Reading the Volt-Ampere Curve Without a Degree in Electrical Engineering

Before we hand you the list of processes, five minutes on the electrical idea behind it will save you months of guessing at machine settings. Almost every mysterious arc problem traces back to one question: is this power source holding my current, or holding my voltage?

The Plain-Language Version

A welding arc is a variable electrical load. Your hand moves, the workpiece shifts, the electrode burns away, and the gap between them changes dozens of times a minute. Every welding power supply is built to hold one of those variables steady while everything else drifts around it. A constant current (CC) machine holds amperage steady and lets voltage swing. A constant voltage (CV) machine holds voltage steady and lets amperage swing. That one design choice is what separates a stick welder from a MIG welder.

What the Curve Actually Looks Like

Graph the output of a CC machine and you get a steeply falling line: as current rises a little, voltage drops a lot. Welders call it a drooping characteristic, and the TWI’s technical note on manual metal arc equipment confirms that MMA/SMAW runs on exactly that drooping curve, typically at welding currents of 50–300 A and voltages in the 10–50 V range. Graph a CV machine instead and you get a nearly flat line: current can jump by a hundred amps while voltage barely budges.

Here is where it gets practical. On a CC machine, your hand drifts and the arc stretches from 3 mm to 5 mm. Voltage climbs to hold that longer gap, but amperage barely moves, so the heat going into the plate stays essentially what you dialed in. On a CV machine, that same 2 mm slip swings current dramatically, because on a flat curve a small voltage change produces a large current change. Real arc voltages during welding usually land around 20–35 V, while an open-circuit stick machine sits at roughly 50–80 V before the arc strikes. Conventional transformer-type welding power supplies typically deliver around 17–45 open-circuit volts anywhere from 55 to 590 amperes.

The analogy that sticks with most welders is cruise control versus throttle. A CC machine is cruise control: you set the speed, and hills (arc length) do not change it much. A CV machine is a throttle: press it and it responds instantly and proportionally. Neither is better; they answer different questions.

Why Manual Processes Want Constant Current

A human cannot hold a perfect arc length. The electrode shortens as it burns, slag tugs at the tip, your wrist angle changes around a pipe corner, and gravity pulls differently in overhead. If each of those wobbles dumped extra amps into the plate, you would burn through thin metal every time you hesitated. With CC, you can vary arc length slightly and still count on a fixed number of amps reaching the material. That is why our guide to welding electrodes leans so hard on amperage-per-diameter settings instead of voltage numbers: amperage is the number the machine is actually protecting for you.

Why Wire Feed Processes Want Constant Voltage

Wire feed flips the logic. Molten metal transferring across the gap wants a stable, predictable arc length, and no human hand can police a wire that is moving continuously. Put a CV source behind a wire feeder and the loop closes itself: the arc shortens, current rises, the wire melts faster, and arc length is restored in a fraction of a second. That self-correcting loop is the reason setting up a MIG welder is mostly a matter of picking a voltage and a wire speed and letting the machine do the regulating. Our TIG sheet metal guide shows the opposite end of that spectrum, where you are the regulator.

Both paths feed one number that ultimately decides whether your weld holds: heat input, roughly amps × volts × travel speed, divided by a process efficiency factor. CC keeps the amps term stable so you control heat with your hand and travel speed. CV keeps the volts term stable so the machine controls heat for you.

Keep that distinction in your head as you read the process list next, because it explains every choice in it.

The Direct Answer: Every Welding Process That Normally Runs Constant Current

Enough theory. Here is the list you actually searched for, delivered without a scavenger hunt through eight hundred words of filler. The welding processes that normally run on a constant current (CC) power source are:

• SMAW (Shielded Metal Arc Welding), better known as stick welding
• GTAW (Gas Tungsten Arc Welding), better known as TIG welding
• PAW (Plasma Arc Welding), TIG’s closely related, constricted-arc cousin
• Carbon arc gouging and air carbon arc cutting (ACAC)
• Gravity welding and firecracker welding, automated SMAW variants
• Certain mechanized CC configurations of processes usually associated with constant voltage

That last point is the thread that ties the whole list together. As the TWI technical knowledge base explains, constant current sources are used for welding operations performed manually, such as SMAW and GTAW, precisely because the arc length is not constant throughout the operation. Every process on the list above is either manual by nature or derived from a manual process. The machine does not control the arc gap; a person does. So the power source’s only job is to keep current, and therefore heat input, stable no matter what the welder’s hand does.

SMAW: The Textbook Constant Current Process

Stick welding is where CC machines were born and where they still live most comfortably. A complete SMAW setup typically consists of a constant current welding power supply, an electrode holder, a ground clamp, and welding cables, as the standard process description confirms. There is no wire feeder, no voltage dial, and no automatic arc-length correction. The electrode burns away, the welder feeds it forward by hand, and arc length breathes with every millimeter of movement. A CC machine absorbs that variation. If you want the full rod-selection picture, our guide to welding electrodes and their numbering system goes much deeper.

GTAW: Precision That Cannot Survive Voltage Fluctuation

TIG welding uses a constant current power source specifically so that current and heat flux remain relatively steady even if arc distance and voltage change, per the GTAW process reference. That matters enormously because TIG welders work on thin stainless, aluminum, magnesium, and aerospace tubing where an extra twenty amps for even half a second burns a hole clean through. On a CC machine, hovering slightly high on the arc only costs you shielding and a little cleaning action, not your workpiece. For sheet-metal-specific settings, see our complete TIG sheet metal guide.

PAW: Plasma Arc Welding

Plasma arc welding shares GTAW’s tungsten electrode but adds a constricting nozzle that focuses the arc into a tighter, more energetic column. That focused arc is unforgiving of current swings, which makes CC the only sensible choice. PAW is frequently automated, but note the nuance: automated here means the torch travels mechanically while a human or program still sets and holds arc distance, so the CC requirement stands.

Carbon Arc Gouging and Air Carbon Arc Cutting

Less glamorous but genuinely common in demolition, backgouging, and defect removal, carbon arc gouging uses a carbon electrode and a blast of compressed air to blow away molten metal. The arc has to stay forceful and consistent through brutal conditions, and a drooping CC characteristic delivers exactly that. It is the same electrical logic as stick welding, just pointed at removal instead of joining.

The Niche Entries: Gravity Welding and Firecracker Welding

Gravity welding, an automated SMAW variation sometimes called gravity arc welding, still uses a constant current welding power supply with either DCEN or AC, because the electrode slides along the joint under its own weight while a person still watches and controls the arc. Firecracker welding, where a rod is laid in the joint and ignited, follows the same rule. One related process worth knowing about, even though it is fusion-by-chemical-reaction rather than arc welding, is aluminothermic rail welding.

The Important Caveat: Normally Does Not Mean Always

Submerged arc welding and flux-cored arc welding are usually constant voltage processes, but both can be run CC with a voltage-sensing wire feeder in specific mechanized setups. Stud welding and resistance processes like spot welding sit entirely outside this conversation, because they run on transformers, timing circuits, and capacitor banks rather than a continuously maintained arc.

So the direct answer stands: stick, TIG, plasma arc welding, and carbon arc gouging are your constant current processes, with a handful of automated and mechanized variants following the same rule. Every one of them shares a single trait: a human hand, not a machine, sets the arc length. Understanding that logic instantly makes the CV side of the equation easier, which is where we are heading next.

SMAW (Stick Welding): The Classic Constant Current Process

If constant current had a poster child, it would be shielded metal arc welding. Ask any welding instructor, and stick welding is the first process they reach for when they need to demonstrate what a drooping volt-ampere curve actually feels like in your hand. The power supply used in SMAW has constant current output, which ensures the current, and therefore the heat, stays relatively steady even as the arc length and voltage wander around. That single design choice is why a half-century-old stick machine still runs a clean 6010 root pass today.

Why a Human Hand Can Never Hold a Perfect Arc

Think about what a stick welder is actually doing. The electrode is a consumable: it burns away as you weld, shortening by the second. The flux coating melts into slag that can momentarily bridge or distort the arc. The welder’s wrist is moving along a joint, the body is shifting, and every one of those movements nudges the distance between the rod tip and the puddle. As the TWI technical knowledge base explains, the arc voltage in SMAW is really a stand-in for arc length: pull the rod further away and the voltage climbs, push it closer and the voltage drops.

On a constant current machine, that voltage swing barely disturbs the amperage. The welder gets something wonderfully practical: a small, intuitive throttle. Nudge the arc out slightly and you get a touch more voltage and a slightly cooler, more controllable puddle. Shorten it up and penetration increases. Because current is never maintained absolutely constant on real machines, skilled welders performing complicated welds deliberately vary arc length to cause minor current fluctuations. It is finesse, not force, and it is the reason an experienced pipe welder can run a root, a hot pass, and a cap with the same rod and the same machine by changing nothing but technique.

Electrodes Choose the Polarity, Not the Other Way Round

Rod selection and power source choice are two halves of the same decision. The classic example is the 6010 family. E6010 is a fast-freeze, all-position cellulosic electrode with deep penetration, and it is operated on DCEP, where the deep arc action bites through rust, paint, and poor fit-up. E6011 uses a similar coating formulation that allows AC in addition to DCEP, which makes it the rod of choice when you are stuck with an old AC buzz box or an engine-driven machine that won’t hold a stable DC arc. At the other end of the spectrum, low-hydrogen rods like E7018 demand clean, dry handling and reward you with a smooth, crack-resistant bead on critical steel.

That is why rod type influences whether AC or DC is preferred, and why the polarity terminals on the front of your machine are the first thing you should check. If you want the full decoding system behind those digits, our guide to what electrodes are in welding breaks down types, numbering, polarity, and selection in plain language.

The Workhorse of the Industry

SMAW dominates the maintenance and repair industry and accounts for over half of all welding in some countries, according to industry surveys of the process. There is good reason for that: it needs no shielding gas bottle, tolerates wind and dirt, and works in any position, overhead included. You can drag a stick welder onto a rooftop, into a ditch, or up a ladder, and the constant current output means the arc stays forgiving even when your body position is anything but comfortable.

That versatility comes with a productivity tax. The operator factor, meaning the percentage of an operator’s time actually spent laying weld, sits at approximately 25 percent in SMAW. The rest is consumed by chipping slag, changing consumed electrodes, grinding, and fitting. A single 14-inch rod might give you two or three minutes of arc time before you stop, discard the stub, and grab a fresh one. Compared to a wire feeder running continuously, that is a big gap, and it is the main reason high-volume fabrication shops moved to CV wire processes.

For real-world settings, a 3/32 E7018 amperage guide and the companion 5/32 E7018 settings breakdown give you concrete starting points by rod diameter, and our honest beginner’s guide to stick welding sets expectations for the learning curve. And if your stick work trends toward thin material, read our stick welding thin metal guide before you turn the dial too far.

Setting Amperage, Not Voltage

Here is the practical takeaway. On a constant current machine, you set amperage and let arc length produce the voltage. There is no voltage dial, and pretending otherwise is how beginners get into trouble. Pick the rod, match the amperage range printed on the electrode box or the machine’s chart, and control heat with your hand. Get that relationship right, and stick welding becomes far less mysterious than Marcus’s frustrating first afternoon suggested.

GTAW (TIG) and Plasma Arc Welding: Precision Demands a Constant Current Source

If SMAW is the textbook example of constant current, GTAW is the reason the textbook exists. Gas tungsten arc welding is where the CC logic stops being a convenience and becomes a requirement, because TIG is the most hand-sensitive arc process most welders ever touch.

Here is the core reason, from the physics: GTAW uses a constant current power source so the current, and therefore the heat flux into the joint, stays relatively constant even as arc distance and voltage change. The amps you set are the amps you get, whether your hand sits 3 mm or 4 mm off the puddle. That stability matters because maintaining a suitably steady arc distance is difficult with a constant voltage source, which can cause dramatic heat variations and make welding far harder.

Why a Voltage Machine Would Ruin a TIG Weld

Picture the technique itself. One hand holds the torch with a non-consumable tungsten electrode; the other feeds filler rod into the leading edge of the puddle. Your torch hand rests on nothing. It floats, tracking the joint and adjusting distance dozens of times per second based on what your eyes tell you.

On a CV machine, every one of those movements would swing the amperage violently. Drift a millimeter longer and the current spikes, and a 1.6 mm stainless sheet blows through. Ease in too close and the current collapses, leaving a cold, un-fused lump. On a CC machine, that drift only nudges voltage; the amps stay pinned. You keep arc-length control over heat without losing your baseline.

This is why TIG thrives exactly where welding gets delicate:

• Thin stainless steel and sheet metal fabrications
• Non-ferrous metals such as aluminum, magnesium, and copper alloys
• Aerospace components, where every weld is inspectable and traceable
• Small-diameter thin-wall tubing, including bicycle frames
• Root and first-pass welds on pipe, which set the quality of the whole joint
• Critical sealing work, such as spent nuclear fuel canisters

For a deep dive into the sheet-metal end of this, see the complete guide to TIG welding sheet metal.

The Tungsten That Makes It Possible

None of this works without an electrode that refuses to melt. Tungsten is used precisely because it has the highest melting temperature of any pure metal: 3,422 °C (6,192 °F). The arc can run for hours with the electrode barely degrading, so the arc geometry stays predictable and the CC source keeps feeding stable current into a stable gap.

The torch has its own limits. Air-cooled GTAW torches are fine for low-current work up to roughly 200 A; above that the heat coming back down the torch becomes punishing, and water cooling is required up to about 600 A. If you are shopping for torch hardware, the cable and connection side is covered in welding connectors explained.

Polarity and Current Type: Choosing the Right Flavor of CC

Constant current is only half the setup. The other half is which direction it runs:

• DCEN (electrode negative) is the standard for steels, nickel alloys, and titanium. Most of the heat sits in the workpiece, giving good penetration and a tight, controllable arc.
• DCEP (electrode positive) drives heat back into the tungsten, giving shallow penetration plus a surface cleaning action. Rarely used alone in GTAW, but instructive for understanding the balance.
• AC is the choice for aluminum and magnesium. It alternates polarity each half cycle, combining the cleaning action that blasts away the tenacious oxide layer with the penetration needed to fuse the metal.

Plasma Arc Welding: The Same Logic, Constricted

Plasma arc welding is GTAW’s close relative and a constant current process in its own right. The difference is a constricting nozzle that squeezes the arc into a narrower, hotter, more focused jet. That focused arc can pierce and weld in a single pass, and because PAW’s arc column is so stiff and well defined, it suits mechanized and automated setups where the machine holds arc distance and the CC source holds current.

There is also pulsed current, where the source alternates between a high peak current that melts the puddle and a lower background current that lets it solidify slightly. Pulsing is how TIG welders control heat on thin material without giving up penetration, and it only works cleanly because the underlying source is constant current.

And if the acronym throws you off, some people search for “WIG welding” instead of TIG; we clear up that naming confusion in what is WIG welding. Either way the requirement is identical: constant current, because the hand controlling arc distance deserves a machine that will not punish it for every millimeter.

Beyond the Big Two: Other Constant Current Applications Welders Overlook

SMAW and GTAW are the headline answers, but a complete answer to which welding processes normally use a constant current power source has to reach past the big two. Several quieter processes depend on the same drooping volt-ampere characteristic, and a few common methods sit entirely outside the CC-versus-CV debate.

Carbon Arc Gouging and Air Carbon Arc Cutting

Carbon arc gouging uses a plain graphite or carbon electrode with no flux coating, and it works on a constant current source. The welder strikes an arc, melts the base metal, and a jet of compressed air blasts the molten pool out of the groove. Because the electrode is dragged along the joint by hand at a constantly shifting angle and distance, the arc length wanders. A drooping characteristic keeps amperage steady through that wander, so the arc stays forceful instead of sputtering out halfway through a gouge. Air carbon arc cutting works the same way, just deeper and more aggressively, and both processes are common for removing defective welds, back-gouging a root, and cleaning up castings. As the welding power supply overview explains, manual and semi-manual arc processes are the natural home of constant current behavior.

Plasma Arc Welding and Plasma Gouging

Plasma arc welding (PAW) is essentially TIG’s focused cousin: a non-consumable tungsten electrode sits inside a torch with a constricting nozzle that squeezes the arc into a tighter, hotter column. That constriction raises energy density and makes the process well suited to precision joints, and it runs on constant current for the same reason GTAW does, the operator’s hand sets the arc distance. Plasma gouging and plasma cutting follow the same rule. Pulsed plasma is still a constant current source being modulated over time rather than a switch to constant voltage.

Gravity Welding and Firecracker Welding: SMAW Without the Hand

Two automated SMAW variants rarely make it into beginner discussions. Gravity welding mounts a coated electrode at a fixed angle above the joint and lets arc force plus gravity walk it down the seam. Firecracker welding lays a run of joined electrodes into the groove and ignites them in sequence. Neither has a hand holding arc length, yet both remain constant current jobs because the drooping curve cushions the short circuits and scrapes that occur as the electrode advances. They are SMAW under the hood, and the power source responds like SMAW.

Mechanized SAW and FCAW: Where the Feeder Becomes the Hand

Submerged arc welding and flux-cored arc welding default to constant voltage in production, which section seven covers in detail. The nuance here is that both can be run on a constant current source when the setup includes a voltage-sensing wire feeder. That feeder watches arc voltage, interprets it as arc length, and speeds or slows the wire to hold the gap steady, effectively doing the job a welder’s wrist would do. It is a legitimate configuration on heavy fabrication rigs and long mechanized runs, especially on Pipe Welding Procedures: The Complete Guide to WPS, Positions, Passes & Inspection style work where travel speed and heat input are tightly controlled. For more on the process itself, see the flux-cored arc welding reference and our own Flux Core Wire Welding Tips: Pro Techniques for Cleaner Stronger Welds.

Stud Welding and Resistance Welding: Outside the CC/CV Framework

Drawn arc stud welding is a short, controlled arc event followed by a plunge, and it is typically handled by dedicated stud welding equipment with its own timing rather than a general-purpose welder. Resistance welding leaves the debate behind completely. Spot and projection welding run on transformers, timing circuits, and large capacitor banks that dump a known energy into the joint over a set number of cycles, with no open arc whose length needs regulating. There is no volt-ampere arc curve to hold flat or drooping, so calling a spot welder CC or CV simply does not apply. Our Spot Welding Copper: A Practical Guide to Parameters & Process Control walks through how those parameters are actually set.

The Inverter Reality: One Machine, Both Characteristics

This is where the old hardware divide gets blurry. An inverter converts incoming mains AC, typically 50 Hz, into high-frequency AC around 50 kHz, then transforms and rectifies it to DC. Because the output is governed by a microcontroller instead of a big moving coil, pulsing, variable duty ratios, and swept frequencies can all be adjusted in software in real time. The practical payoff is a single compact unit that switches between constant current and constant voltage modes, which is exactly the selling point of a MIG TIG Combo Welders: The Complete Guide to Buying and Using One. Smaller, lighter, and far more controllable than the transformer-rectifier machines of the past.

Engine-Driven Generators for Field Work

Where no mains supply exists to be transformed, welding power supplies may use generators or alternators driven by an internal combustion engine. These engine-driven units are the backbone of pipeline and remote-site work, and they are commonly configured as constant current machines for stick and TIG, since those are the processes you can run on a hillside without a gas bottle rack or a wire feeder.

When Constant Voltage Takes Over: MIG, Flux-Cored, and Why Wire-Feed Flips the Logic

Here is the half of the question nobody asks out loud: if constant current is so stable, why do the busiest machines in nearly every production shop run on constant voltage? The short answer is that CV solves a problem a human hand cannot. Once wire enters the picture, arc length stops being something you control and starts being something the machine has to police for you.

The Self-Correcting Arc

Most applications of gas metal arc welding use a constant voltage power supply, because on CV any change in arc length, which relates directly to voltage, results in a large change in heat input and current. That sounds alarming until you see how it behaves in the opposite direction.

Picture the arc drifting short. On a CV machine the current jumps, heat input climbs sharply, and the wire electrode melts back faster than before. The arc grows to its original length and the current settles down. Nudge it long and the reverse happens: current drops, the wire feeds out longer, and the arc shortens again. The system corrects itself dozens of times per second without you doing anything.

Compare that to stick welding, where the rod is burning away in your hand and you are the only thing holding arc length steady. A drooping CC source forgives a shaky hand. A wire feeder gives you no such forgiveness, so the machine has to supply the forgiveness instead. It is the same logic as cruise control versus a throttle: CC holds the current steady while you work the pedals, CV holds the speed steady while the hills change. If you want the deeper electrical side of this, our complete guide to TIG welding sheet metal walks through how manual processes handle the same problem from the operator’s side.

Metal Transfer Modes and Their Windows

Why does a wire process need such a wide current swing? Because GMAW runs in several distinctly different transfer modes, and each one lives in its own narrow parameter band:

• Short-circuit transfer generally uses about 100–200 amperes at 17–22 volts, ideal for thin sheet and out-of-position work where you need low heat.
• Globular transfer sits above that range, runs rougher, and is usually avoided for visible beads.
• Spray transfer is generally used on workpieces above about 6.4 mm (0.25 in) thick, delivering high deposition and deep penetration in the flat position.
• Pulsed spray alternates between a peak and a background current on a CV source, giving spray-like transfer with less heat on thin material.

Shielding gas flow matters just as much as amperage. Expect roughly 10 L/min for short-circuit and pulsed spray, about 15 L/min for globular, and 20–25 L/min for spray transfer. Push the flow higher than that in a drafty shop and you actually start entraining air. Our step-by-step MIG welder setup guide covers gas, wire speed and drive roll tension in one pass.

Flux-Cored Wire: CV by Default, CC by Exception

Flux-cored arc welding requires a constant-voltage or, less commonly, a constant-current welding power supply. In practice nearly every FCAW rig you meet is CV, because self-shielded and gas-shielded tubular wire both depend on that self-regulating arc. The CC variants show up where a voltage-sensing wire feeder is installed, letting the feeder adjust travel speed to hold arc voltage while the source holds current. If you are chasing cleaner, stronger flux-cored results, our flux core wire welding tips collection is the natural next read.

The CC Exceptions Worth Knowing

GMAW can be run with a constant current power source paired with an arc voltage-controlled wire feed unit, and in rare cases CC with constant wire feed is used for metals with high thermal conductivity such as aluminum, where the puddle simply will not behave on a CV curve. Both setups demand significant skill: you become the feedback loop. That is why aluminum MIG work has a reputation for punishing新手 mistakes.

Modern multi-process inverters blur the line further by switching modes at a button press, which is exactly what makes machines like the ones in our MIG TIG combo welder guide attractive to small shops. The hardware no longer decides the process for you; your understanding of CC versus CV does.

The decision rule stays simple: a hand controls arc length, use constant current. A machine controls arc length, use constant voltage. Everything else is detail.

Dials, Dials Everywhere: Setting Up and Running a Constant Current Machine Correctly

When you fire up a constant current (CC) machine for stick or TIG, the first thing you need to know is this: you set amperage, not voltage. Unlike a wire-feed unit, a CC power source lets voltage become a byproduct of your arc length. The closer you hold your electrode or tungsten to the puddle, the lower the voltage runs. The longer your arc drifts, the higher the voltage climbs. Your job is to keep that arc tight enough to stay stable, while the machine keeps the heat input consistent. This simple shift is what trips up so many welders coming over from MIG, and it’s exactly why learning the dials on a CC unit pays off.

Open-Circuit Voltage, No-Load Safety & Confined Spaces

Before you strike an arc, take a second to respect open-circuit voltage (OCV), also called no-load voltage. This is the voltage present at the output terminals with no arc running. The TWI guide to MMA equipment explains that the no-load voltage rating of a power source is defined by welding power supply standards, with key references in IEC 60974-1 and IEC 60974-6. These ratings exist to match the machine to the welding environment and limit the electrical shock hazard.

Also pay close attention to your welding cable connectors. Loose lugs, frayed leads, or corroded terminals add resistance, create hot spots, and raise your risk of shock. For electrode holders, stick to units that conform to IEC 60974-11, as poor contact between the electrode, holder, and cable is one of the most overlooked causes of resistance heating.

Duty Cycle, Amperage Selection & A Starter Cheat Sheet

Every CC machine has a duty cycle. In plain terms, it’s how many minutes out of ten you can weld at a given amperage before the unit needs to cool. Run above that rating and you’ll trigger thermal shutdown. Before chasing a “hotter” setting, check the nameplate for your exact machine.

Picking the right amperage comes down to electrode diameter and base metal thickness. Choosing too low leads to poor fusion, while going too high causes excessive spatter, undercut, and burn-through on thin stock. If you’re new to stick, our honest beginner’s guide to stick welding is a solid place to build muscle memory. For more precise numbers, see our electrode breakdown, along with rod-specific pages like 3/32 E7018 amperage and 5/32 E7018 amperage.

Modern CC Features, AC vs DC, Polarity & Cable Sizing

Today’s MIG/TIG combo welders often pack features that take the fight out of a CC arc. Hot start gives a brief amperage boost to help strike stubborn rods. Arc force/dig prevents the arc from “going dead” when you push in slightly, keeping penetration steady. Pulse (common on TIG-capable inverters) lets you toggle between peak and background amps to control heat on thin sections, a huge help when working with the tips found in our TIG sheet metal guide or stick welding thin metal guide.

Next, pick your current type. DC electrode positive (DCEP) or DC electrode negative (DCEN) both see heavy use, but AC is your go-to anytime you need the arc to break up oxide, most often on aluminum with TIG. Polarity must match your electrode: for example, many low-hydrogen rods demand the correct polarity to run smooth. Don’t guess—check the rod box or our push vs pull stick welding breakdown.

Finally, size your leads correctly to avoid voltage drop over long runs. Undersized cables rob you of usable amps at the work, make arc starts harder, and overheat. For field work or long stingers, bump up your cable gauge. This is just as vital for out-of-position jobs like overhead stick welding or critical code work seen in pipe welding procedures.

Set your amperage, verify polarity and cables, confirm your duty cycle, and let arc length do the rest. Get those basics right, and the CC dial stops looking mysterious and starts working for you.

Common Mistakes and How to Fix Them on Constant Current Equipment

Knowing that SMAW and GTAW run on constant current is only half the battle. The other half is avoiding the handful of mistakes that send beginners chasing a problem back to the machine when the machine was never the problem. Most CC complaints come down to four setup errors, one physics quirk called arc blow, and a welding rod that was stored in the wrong place. Here is how to spot each one and fix it in minutes.

Four Setup Mistakes That Sabotage a Constant Current Machine

• Feeding MIG wire into a CC-only stick machine. A wire feeder needs a voltage setpoint to hold arc length steady. On a drooping CC source the feeder never gets one, so the wire either burns back to the tip or stubs into the plate. If you want to run wire, you need a CV mode or a voltage-sensing feeder. The MIG welder setup walkthrough covers what a proper wire-feed circuit requires.
• Twisting a voltage dial that does not exist, then guessing. On a CC unit, voltage is an output of arc length, not a setting. You set amperage for the electrode and material, then let the hand control the volts. If your machine shows a voltage readout climbing and falling while your amps hold steady, that is the drooping curve working correctly, not a fault.
• Ignoring polarity. This is the number-one cause of a rough, spattery arc with E7018 and with self-shielded flux-cored wire. Run 7018 on DCEP and the arc smooths out instantly; the 3/32 E7018 amperage and polarity guide shows the exact window. Getting the acronyms right matters too, so review the electrode classification and polarity guide if DCEN, DCEP and AC still blur together.
• Buying a DC-only machine for aluminum. Aluminum wants AC for the cleaning action of the positive half-cycle. A DC-only TIG unit will weld steel and titanium all day and struggle on aluminum until you add an AC output or an external controllable arc unit.

Arc Blow: The DC Problem That Looks Like a Bad Electrode

Magnetic arc blow is a constant-current side effect you can actually see. On DC, the magnetic field around the arc pushes it sideways, most often at the end of a run or into a corner, producing a wandery arc, spatter and even porosity. Try three fixes in order: move the work clamp to change the current path, reverse polarity, and if the wander persists, switch the machine to AC. As TWI’s equipment notes on manual metal arc explain, arc blow is tied directly to how the power source and lead arrangement are configured, so it is a setup issue before it is a technique issue.

Defects and Their CC-Related Causes

Common SMAW quality problems are weld spatter, porosity, poor fusion, shallow penetration and cracking. Almost all of them trace back to arc length, current setting or electrode condition.

Electrode Storage: The Mistake Made Before You Strike an Arc

Basic and basic/rutile low-hydrogen coatings pick up moisture fast, which is exactly what turns into porosity in the weld. They should be thoroughly dried in a controlled oven, typically about one hour at roughly 150–300 °C, then held at 100–155 °C in a rod quiver until use. Cellulosic rods are a different story: their coating is designed to operate with a definite amount of moisture and generally does not require any drying at all. Following manufacturer storage guidance is also why SMAW electrode classification includes coating designators in the first place.

On the GTAW side, the classic CC mistake is pushing current past what the tungsten can carry. If the current exceeds the electrode’s capability, you get tungsten spitting and tungsten inclusions trapped in the weld, which are detectable by radiography. Drop the amperage, regrind the tungsten, and check the TIG sheet metal mistakes guide for a fuller checklist.

Conclusion: Match the Machine to the Hand, the Wire, and the Job

If you remember one sentence from this article, make it this one: when a human hand controls the arc length, the machine should hold the current constant; when the machine feeds the wire and controls the arc length, it should hold the voltage constant. That single rule explains every process we have covered, and it is the fastest way to answer “which welding processes normally use a constant current power source?” before you touch a dial.

The definitive list, one more time: SMAW (stick), GTAW (TIG), plasma arc welding, and carbon arc gouging and air carbon arc cutting run normally on constant current, with gravity welding, firecracker welding, and certain mechanized setups as niche extensions. Submerged arc and flux-cored processes usually default to constant voltage but can run CC with the right feeder, and resistance processes like spot welding sit outside this arc-power conversation entirely. As we covered in the basics of welding power supply design, the drooping CC curve and the flat CV curve are deliberate engineering choices, not brand preferences.

Why the Modern Inverter Makes This a Question You Must Ask Every Time

On an old transformer stick welder, the machine’s identity was obvious: it either was or was not a CC machine. Today’s MIG TIG combo welders and multi-process inverters switch between CC and CV output with a button press, which is wonderful for shop flexibility and dangerous for anyone who assumes the mode. Striking a stick arc on a welder still set to CV, or running MIG while the machine sits in CC, produces the exact frustrating experience that opened this article: an arc that fights back. The practical skill is no longer owning the right box. It is knowing which mode to select, and why, before you strike the arc.

Your Pre-Weld Action Checklist

Run through this quick sequence at the start of any job on CC equipment:

• Verify the machine mode on a multi-process unit: CC for stick and TIG, CV for wire feed.
• Confirm polarity and electrode type. DCEP for E7018 and E6010, AC for E6011 and aluminum, DCEN for most TIG work. Our 3/32 E7018 amperage and polarity guide shows how much difference getting this right makes.
• Set amperage, not voltage. On a CC machine voltage is a byproduct of arc length, so dial in amps by rod diameter and material thickness.
• Check the duty cycle against your planned weld time so the machine does not thermally cut out mid-pass.
• Inspect cables, holders, and connectors for heat damage and loose contact, since poor connections steal amperage you cannot see on the dial. Our welding connector troubleshooting guide is worth a read here, and wire-feed users can dial in the rest with the complete MIG setup walkthrough.

Keep Your Judgment Sharp, and Yourself Safe

Understanding the CC/CV logic does something bigger than help you set a dial. It gives you a working theory of the arc, so when a weld behaves strangely you can reason about whether the problem is current, arc length, polarity, or technique instead of guessing. That is the difference between a welder who struggles and a welder whose judgment other people trust. From TIG on thin sheet to pipe procedures and exotic processes like aluminothermic rail joining, the same question keeps reappearing in different clothes: who is holding the arc length?

One last reminder before you head to the machine. Power source behavior is only half of a safe setup. OSHA addresses welding, cutting, and brazing hazards through dedicated standards and hazard guidance pages, covering ventilation, electrical shock, fire prevention, and eye protection. Fume exposure deserves the same seriousness: NIOSH recommends an exposure limit of 1 mg/m³ as a time-weighted average and 3 mg/m³ as a short-term limit for manganese, while OSHA’s permissible exposure limit is 5 mg/m³ as a ceiling. Pair that with proper welding PPE, fume extraction at the source, and the right lens shade for the amperage you are running.

Match the machine to the hand, the wire, and the job, verify the mode before you strike an arc, and the arc gets a lot friendlier once you understand what the machine is actually trying to do for you.

Frequently Asked Questions

Which welding processes normally use a constant current power source?

The classic constant current processes are shielded metal arc welding (SMAW or stick), gas tungsten arc welding (GTAW or TIG), and plasma arc welding (PAW). Carbon arc gouging and some automated SMAW variations such as gravity welding also use constant current, and a few submerged arc or flux-cored setups can be configured for it as well.

Why do SMAW and GTAW use constant current instead of constant voltage?

Both are manual processes where the welder’s hand cannot hold a perfectly steady arc length. A constant current machine adjusts voltage to keep amperage steady, so small changes in arc length do not cause wild swings in heat input. With a constant voltage source, the same movement would create dramatic heat variations and make welding much harder.

Can you run MIG (GMAW) on a constant current machine?

Yes, but it is not the norm. GMAW can run on constant current if the wire feeder senses arc voltage and adjusts feed speed, and in rare cases with a constant feed rate for high-conductivity metals like aluminum. These setups demand more skill and are far less common than the standard constant voltage approach.

What does a ‘drooping characteristic’ mean?

Drooping is the traditional nickname for a constant current volt-ampere curve. As current rises, output voltage falls steeply, which is exactly what a manual welder needs so that arc-length changes do not translate into large heat changes.

Do I set voltage or amperage on a stick welder?

On a constant current machine you set amperage; voltage is a byproduct of arc length. Setting expectations based on a MIG machine’s voltage dial is a common beginner mistake. Match your amperage to the electrode diameter and material thickness, then let arc length fine-tune the arc.

Is a constant current machine good for beginners?

Yes, especially for stick welding. Because current stays nearly constant, small hand movements do not instantly ruin the weld, which makes learning more forgiving. Constant voltage MIG is arguably easier to start with, but a CC stick machine remains an excellent, low-cost learning platform.

How can I tell if my welder is constant current or constant voltage?

Check the machine’s data plate and duty-cycle label for terms like CC, CV, or ‘drooping’ versus ‘flat’ characteristics, and look at the terminal or mode markings. Multi-process inverter machines can switch between CC and CV, so verify which mode is selected before you arc up.

What happens if I use the wrong power source for my process?

Using CC for a wire-feed process without the right feeder usually produces an unstable arc and erratic deposition, while using CV for stick or TIG causes dramatic heat swings, spatter, and burn-through. Matching the power source to the process is fundamental to arc stability, penetration, and weld quality.