What Is a Plasma Cutter and How Does It Work?


Metalworking is one of the most important industries today. Whether you work in manufacturing or need parts or products which result from it, or you are on a repair team or rely on one, your life is impacted by welders.

These welders, in turn, rely on their tools. The right tools are needed to complete any task, and in the same way that a painter needs a brush, a lumberjack needs an axe, and a builder needs a hammer, a welder needs a plasma cutter. However, those other tools have been with us for centuries, and are among our most commonplace tools. Plasma cutters, by contrast, are quite new, and remain a mystery to many outside the metalworking profession.

What is a plasma cutter and how does it work? a plasma cutter is a cutting agent which uses plasma to cut into metal surfaces. Plasma cutters work at extremely high temperatures. This means that you need to make sure that you have shielding gases to keep them under control as well as ample safety equipment with which to protect yourself.

What Is Plasma?

With that in mind, however, let’s take a step back and tackle an even more pressing question – what is plasma? It seems like a pretty important thing to know given how central it is to this tool’s operation, as well as the fact that it’s an entire state of matter.

That said, while you know what a solid, liquid, and gas are, chances are that even if you learned about plasma as the fourth state of matter in school, its description is more elusive for you than the other states of matter. This is due in part to the fact that plasma is itself a trickier, less defined state than the others.

Simply put, plasma is superheated gas which, at a high enough temperature, consists of atoms which have lost some or all of their electrons and are thus positively charged, thereby causing them to act differently than other states of matter.

Learn More About Plasma cutter temperatur – Here, you can find an article from our website: How Hot Does a Plasma Cutter Actually Get? Real Facts -2020

For our purposes, that means that plasma is able to be extruded and used as a superhot substance which, while similar to a gas, can be better utilized for welding purposes due to how it can be harnessed.

While gas can be a bit directionless and hard to control, by comparison, plasma can be heated and directed in a specific direction, thus making it ideal for cutting into thick surfaces such as various metals.

It is thus able to achieve greater penetration and accomplish its cutting task in a superior fashion to other welding options.

How Do Plasma Cutters Work?

All that theory is well and good, but what about the practicalities of how plasma cutters work?

As stated above, plasma cutters function by heating up gas so that it becomes plasma, which can then be used to cut into metals, and they do this in part by pushing the plasma through a narrow nozzle at a high speed. Think of a high-powered spray cleaner.

The water comes out of the spray nozzle at such a high speed and with such tremendous force that it literally blasts away debris. The same principle is at work with plasma cutters, which shoot out the gaseous plasma.


In addition, plasma cutters work by sending electricity in an arc through the gas and that narrow nozzle. The gas can and does change depending on the job, and we’ll get into that shortly.

For now, however, know that whichever type of gas you employ, the combination of electricity and superheated pressurized gas make the already-hot substance already hotter and ready to cut into thick aluminum, stainless steel, or other metals. Different metals and thicknesses require different gases and configurations.

Many modern plasma cutters make use of a pilot arc. This is typically located between the nozzle and the electrode shooting the electricity through it. This is used to ionize the gas, which is important for helping with the arc transfer and the overall quality and nature of the plasma.

Plasma cutting for beginners >> Check out the video below

Different Kinds of Gas

The following are the four different kinds of gas commonly used as shielding gases for plasma cutters:

  • Compressed Air: This is by fear the cheapest of the shielding gases listed here, and as a result, it is often used by hobbyists, DIY enthusiasts, and other non-professionals looking for the most affordable welding experience. That said, it can also be used by professionals, providing a good, clean cut for mild and stainless steel.

  • Oxygen: This type of gas is another inexpensive one, and can cut through mild steel extremely well, making it the gas of choice for working with that particular type of metal. That being said, it is limited in terms of its effectiveness with stainless steel and aluminum, and is not recommended for use with those types of metal, in part because it can oxidize them.

  • Nitrogen: Both nitrogen and argon hydrogen make use of different gases besides “normal” air to serve as shield gases to aid with the cutting. Nitrogen makes use of CO2 for this purpose. It is an excellent choice for working with mild steel and aluminum, although it is a bit less effective with stainless steel. In addition, it can produce a bit of dross, so you’ll need to clean away the excess molten metal after you’re done working. Water is another option, which can help it work with certain surfaces better, so you’ll want to check things on a case by case basis.

  • Argon Hydrogen: This is by far the most delicately balanced of the gases on this list. The hydrogen and argon will be mixed at different ratios depending on the type of surface into which you’ll be cutting. While it is not recommended to use this type of gas on mild steel, it can work quite well on stainless steel and aluminum at thicknesses above half an inch.

Which Gas Is Right for You?

The question of which plasma cutting gas is right for the job is answered in large part by the nature of the job itself.

Main GasSecondary GasStainless SteelAluminumMild Steel
Argon-HydrogenNitrogenExcellent cuts in thickness greater than 1/2´Excellent cuts in thickness greater than 1/2´Not effective (cut surface is rough & charred)
AirAirGood cut surface – Fast cut speed – Easy to useGood cut surface – Fast cut speed – EconomicalPerfect cuts – Fast cut speed – Economical
OxygenAirNot recommendedExcellent cut quality – Fast cut speed – Very little debrisNot recommended
NitrogenAirGood cut surface – Longer part LifespanGood cut surface – Longer part LifespanRougher surface – Create some cut filaments
NitrogenWaterExcellent cut surface – Longer part LifespanExcellent cut surface – Excellent part LifespanFair cut surface – Some debris release
NitrogenCarbon dioxideExcellent cut surface – Longer part LifespanExcellent cut surface – Excellent part LifespanFair cut surface – Release some filaments

The first thing you will want to consider when choosing among the different types of plasma cutter gasses is the metal into which you wish to cut. The particular strengths and weaknesses of each gas are noted above. For example, oxygen and air go well with mild steel, while nitrogen tends to work well with stainless steel and aluminum.

One important thing to note here is that most of these gasses offer at least some cutting possibilities with most of the different types of metals. You will rarely run into an instance where a gas flat out won’t work. Rather, it’s all about quality control and affordability.

For example, compressed air tends to be quite affordable, while argon hydrogen is more expensive. That said, the latter is far more effective at cutting into larger and thicker materials, and can also deliver a smoother cut to many of the surfaces listed here.

As such, the affordability question is not a one-sided one. For smaller, quicker, more basic jobs, compressed air may be the more affordable option. For larger, thicker metal surfaces, however, investing in argon hydrogen may be the better bet long-term.

Investing in higher-quality gasses and nozzles over less expensive ones can also pay off long-term.

Finally, some combinations – such as oxygen on stainless or mild steel – are flat out not recommended, so make sure you aren’t running afoul of any of these limitations. That said, in plasma cutting, the only limitations besides these are those of your imagination. As long as you have the right gas-metal combinations, and the right tools for the job, there is no limit to what you can do.

What About the Pilot Arc?

We have already mentioned a pilot arc, but now let’s go into a bit more detail. They are instrumental in modern plasma cutters, increasing their efficiency – but how?

Pilot arcs help you make a cleaner cut with your plasma cutter by helping you avoid touching the tip of the torch directly to the metal.

When you have to press the nozzle close to metal, it can cause significant problems. Not only can it pollute the nozzle, but it can result in more leftover dross. By helping to eliminate that, pilot arcs allow for a smoother, cleaner cut.

This also increases the lifespan of the consumables used by the plasma cutter, as described below.

What About Consumables?

As you might expect, welding takes a lot of energy, and it can wear out the parts used in the process quite quickly. The parts used up in the welding process are referred to as consumables, and as they are “consumed,” you need to replace them over time.

That said, “consumables” is an umbrella term for a wide range of different parts, from retaining caps and electrodes to nozzles and shield gas generators. The lifespan of each of these parts is different, and indeed, different parts from different brands have different lifespans as well.

These lifespans can also vary depending on how the parts are used. Just as we say that “burning the candle at both ends” uses it up quickly, using plasma cutters at higher temperatures or in more intense ways can burn through consumables more quickly.

Thankfully, you can purchase replacement consumable kits which can enable you to keep on cutting. All you have to do is detach the nozzle, replace the parts which have become worn out, and get right back to work.

The Benefits of Arc Cutting

With all of that in mind, what makes a plasma cutter so worthwhile? We know that it can generate an incredibly hot beam which can be used for cutting, but what about that is so important?

For one thing, plasma cutters are incredibly useful for cutting through different metal surfaces, which can prove impossible to do with other tools. As anyone who has ever seen blades saw into solid metal knows, this process can be noisy, spark-laden, and incredibly dangerous. In theory, therefore, plasma cutting can make for smoother and safer cuts.

Related Reading: Can Plasma Cutter Cut Aluminum? | A Complete Guide – 2020

It can also result in cuts which are a lot cleaner. One of the big problems of cutting into metal is that it can lead to a lot of junk or dross being left over. Arc cutters at their best can help avoid this problem by keeping the nozzle from touching the metal, thus making it easier to produce smooth, clean, dross-limiting cuts.

What’s more, because of the tremendous heat involved, the best arc cutting allows for units which can cut through metal like butter.

Then there is the matter of precision. If you are performing cuts which require a great deal of accuracy and precision, arc cutting can be tremendously helpful, especially when compared to sawblades and other approaches.

Questions to Consider

If you have come this far and are still interested in getting a plasma cutter, you’ll want to consider the following additional questions:

  • How thick is the majority of the metal you wish to cut?
  • How thick is the thickest metal you wish to cut?
  • How quickly do you need to perform these cuts?

As alluded to above, argon hydrogen can work quite well with stainless steel and aluminum at thicknesses above half an inch, and this is just one example of how the gas and plasma cutter pairing can have an impact on how well you are able to cut into certain thicknesses.

The faster you perform cuts, the less precise they can be. That said, you can also invest in technology which can help you perform automated cuts at faster speeds.

Then there is the issue of voltage. Different plasma cutters are powered by different amounts of voltage, and give off different amounts of amperage. These amounts are determined by how much power they are compatible of receiving, which can impact where and how you can use them.

For example, voltages around 120 are typically compatible with the kind of power outlets you find around your home. This makes them ideal for hobbyists and those looking to use plasma cutters for DIY purposes, as you can just plug them in and go. Higher voltages, however, such as 250V, will likely be too much for a home socket. You’ll thus need to buy a special adaptor or generator to use these in a safe fashion.

What to Look for in a Plasma Cutter

All of this brings us to a final question – what should you look for in a plasma cutter?

This will naturally vary depending on a variety of factors, not the least of which being what you are looking to accomplish.

For example, if you are looking for a plasma cutter for hobby purposes, such as sculpting metal pieces together, you’ll want to look for something that is affordable, is low on the voltage scale, and makes use of affordable gases such as compressed air.

For those looking to use a plasma cutter for professional purposes, higher voltages are likely desirable. If you need to cut into especially thick metal, you’ll want to look for a plasma cutter which works well with hydrogen argon or nitrogen.

You will also want to look for a plasma cutter which offers a pilot arc for accuracy and ease of use. In addition, a unit with easily replaced consumables can save massive headaches later on.


Plasma cutters are intricate machines, but the basic idea behind them is simple – they are super hot and cut super smoothly and cleanly. Used properly, they can be the tool you need to cut through your next metal welding project with ease.

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David Harper

David is the Co-Founder and Senior Editor at weldingtroop.com. David's an experienced fitter and tuner/welder who's passionate about helping others develop in life through new skills and opportunities.

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