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.
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.
One question that often arises about plasma cutters is whether they can operate without gas. In this comprehensive guide, we will explore the different types of gases used in plasma cutters, the benefits and drawbacks of using gas, and the possibilities of operating a plasma cutter without gas.
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.
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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.
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Can Plasma Cutters Operate Without Gas?
Plasma cutters typically require gas to generate the plasma necessary for cutting. Some units come with a built-in air compressor, while others rely on an external air compressor or gas supply. Although it is possible to use a plasma cutter without an air compressor, doing so may result in reduced cutting precision and portability.
It is essential to choose the right gas for your specific plasma cutting application, as different gases offer various benefits and drawbacks depending on the material being cut and the desired cutting performance.
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Do All Plasma Cutters Require Air?
Plasma cutters do not always require compressed air to function. While most plasma cutters come with an air compressor, some models are built without it. The most commonly used gas for plasma cutting is air, but there are other gases that can be used depending on the thickness and type of metal being cut.
Gas is necessary for the plasma cutter to create plasma, which is used to cut through the metal. Ultimately, the need for compressed air depends on the specific model of the plasma cutter and the desired cutting application.
Can I use Plasma Cutter Without Air Compressor?
Yes, you can use a plasma cutter without an air compressor. While most plasma cutters come with an air compressor, some models are built without it. Plasma cutters use an electrically conductive plasma to cut through various materials and can be used with or without an air compressor. The most commonly used gas for plasma cutting is air, but other gases can be used depending on the metal being cut.
Gas is necessary for the plasma cutter to create plasma, which is used to cut through the metal. The need for compressed air depends on the specific model and desired cutting application. Some plasma cutters can cut metal without the need for an air compressor.
However, if you’re using an air plasma cutter, it’s important to have an air dryer as the quality of compressed air is a crucial factor in the performance of the plasma cutter
How Much Air Flow Does a Plasma Cutter Need?
The air flow or pressure required for a plasma cutter typically ranges from 4-8 SCFM (Standard Cubic Feet per Minute) delivered at 90-120 PSI (Pounds per Square Inch), depending on the size and cutting capacity of the unit. However, the specific air flow requirements may vary between different plasma cutting systems.
For instance, the Hypertherm Powermax45® plasma cutter requires 6 cubic feet per minute of air flow. It is crucial to match the air compressor to the plasma cutter and ensure proper air quality by using an air drying/filtration system to avoid damage to the system and poor-quality cuts.
Can You Plasma Cut Aluminum With Air?
Yes, it is possible to use regular air as plasma cutting gas with aluminum, but the surface finish will be rougher compared to using other gases. owever, it is important to note that modern plasma cutting technology has improved processes on lower cost and state of the art systems, and dual gas systems offer fabricators much finer control and a cleaner, quicker cut.
The most important factor is whether the plasma cutter is capable of using the ideal gases at the ideal pressure level and cutting speed. For cutting aluminum that is 3mm or ¼-inch thick, a cheap 50-amp plasma machine and compressed air can be used.
It is important to match the air compressor to the plasma cutter and ensure proper air quality to avoid damage to the system and poor-quality cuts.
The air flow or pressure required typically ranges from 4-8 SCFM delivered at 90-120 PSI, depending on the size and cutting capacity of the unit.
Choosing the Right Gas for Your Plasma Cutter
To choose the right gas for your plasma cutter, consider the following factors:
- Material Type: Different gases work best on different materials. For example, oxygen is ideal for cutting mild steel, while hydrogen is suitable for cutting aluminum and stainless steel.
- Material Thickness: The thickness of the material being cut will also determine the best gas to use. For example, nitrogen is effective for cutting materials up to 3″ thick, while argon-hydrogen mixtures can cut through materials up to 6″ thick.
- Budget: The cost of the gas should also be considered when choosing the right gas for your plasma cutter. Compressed air is the most affordable option, while gases like oxygen and nitrogen can be more expensive.
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.
Plasma Cutting Applications
Plasma cutting has a wide range of applications in various industries and everyday life. Some of the most common uses for plasma cutters include:
- Custom automotive shops for creating chassis and frames
- Construction workers for cutting and shaping metal beams and structural components
- Locksmiths for cutting through metal doors and locks
- Artists and hobbyists for creating intricate metal designs and sculptures
- Metal fabrication shops for cutting and shaping metal parts and components
As plasma cutting technology advances, engineers continue to develop more powerful and compact machines, improving cut quality, increasing cutting speed, and extending consumable life.
Components of a Plasma Cutter
A plasma cutter comprises several essential components that work together to create the plasma cutting process. These components include:
- Power Source: The plasma power supply converts single or three-phase AC line voltage into a smooth, constant DC voltage, which maintains the plasma arc throughout the cut and regulates the current output based on the material type and thickness being processed.
- Work Clamp: The work clamp grounds the workpiece, preventing the high voltage from traveling through the operator’s body and causing harm.
- Arc-Starting Console: The arc-starting console generates an AC voltage of approximately 5,000 VAC at 2 MHz, which produces the spark inside the plasma torch to create the plasma arc.
- Handheld/CNC Torch: The plasma torch, either handheld or mounted on a CNC machine, provides proper alignment and cooling of the consumables, such as the electrode, swirl ring, and nozzle.
- Air Compressor: Although not a required component, an air compressor can provide several benefits when used with a plasma cutter, such as improved cutting precision and portability.
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 Gas||Secondary Gas||Stainless Steel||Aluminum||Mild Steel|
|Argon-Hydrogen||Nitrogen||Excellent cuts in thickness greater than 1/2´||Excellent cuts in thickness greater than 1/2´||Not effective (cut surface is rough & charred)|
|Air||Air||Good cut surface – Fast cut speed – Easy to use||Good cut surface – Fast cut speed – Economical||Perfect cuts – Fast cut speed – Economical|
|Oxygen||Air||Not recommended||Excellent cut quality – Fast cut speed – Very little debris||Not recommended|
|Nitrogen||Air||Good cut surface – Longer part Lifespan||Good cut surface – Longer part Lifespan||Rougher surface – Create some cut filaments|
|Nitrogen||Water||Excellent cut surface – Longer part Lifespan||Excellent cut surface – Excellent part Lifespan||Fair cut surface – Some debris release|
|Nitrogen||Carbon dioxide||Excellent cut surface – Longer part Lifespan||Excellent cut surface – Excellent part Lifespan||Fair 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.
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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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