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Plasma Cutter Gas Types with Their Benefits & Drawbacks

Plasma Cutter Gas

I run a metal and scrap workshop. Therefore, my occupation incorporates cutting and fabricating all sorts of metals. It’s, therefore, not unusual to notice the flames and torches swirling around. And the primary tool of trade here is a plasma cutter.

A plasma torch is simply a highly charged ion that blaze through the electrically charged bases such as metal plates. A plasma ray makes a precise incision on steel, stainless steel, aluminum as well as brass and copper.

A plasma welding machine uses different kinds of gases to tear through metals. The plasma cutter gas transmits an electric arc to split open a thick metal piece. The most popular gases for arc welding include oxygen, air, argon, as well as nitrogen and hydrogen.

Most plasma systems use several gases simultaneously in the welding process. Some gases are included to act as protective gases; making this procedure generate a higher energy density while at the same time provides a lower beam divergence. As such, most plasma cutters use a mixture of gases to enhance their heat intensity. An advanced plasma arc emits about 50,000 amps per square inch on the metal plate.

Continue reading the document to appreciate the types of plasma cutter gases and how each gas affects the welding process. Further, you will understand the advantages and disadvantages of each gas as well as their roles in the process.

Understanding the Plasma Cutter Gas Types

Plasma Cutter Gas Types

During plasma cutting processes, expert fabricators usually mention various gas types. You may be confused by these jargons. Below are the dominant gas types used for plasma cutting operations.  Generally, plasma cutting gas selection conforms to the following classes:

1. Control Fuel

Plasma cutting requires an ideal environment to work well. The way a plasma cutter works allows specific components abide by some conditions to facilitate the accelerated jet of a plasma torch. These include current levels, arc voltages, cutting speed, as well as gases.

A control gas, therefore, is the gas returning from the torch. It allows for the proper identification of the various torch heads during the cutting process. As such, it helps in bringing about appropriate conditions (heat levels and defined energy alignment) ideal for concise plasma operations.

Control fuel is distinct in that it leads to the plasma head. It also regulates the heat around the torch protection nozzle. This configuration ensures that the cut flame ignites only after the correct setting of the plasma head.

2. Plasma Cutter Fuel

Plasma cutters both the basic and high-end models involve different level of heating mechanism. The first stage occurs during the ignition, and then more power flows to begin the cutting stage. Several gases are involved in these two stages.

The first gas combustion at the ignition stage is weak, and the process is incomplete. Therefore, the flames are dark yellow to orange with much smoke. The intensity of the blaze at this juncture is weak and easily flickers under the wind. This flame is due to the plasma cutter fuel.

3. Swirl Fuel

When the plasma cutting process is underway, materials could bend or wrap due to intense heat. This reaction makes cutting less accurate. To prevent this deformities and imperfections, fabricators use swirl fuel.

Swirl fuel insulates the metal work plate from direct heat by cooling the arc. As such, it enhances a higher cut precision while protecting the project materials from flaking by allowing quick cooling mechanism.

Different gases are used to provide swirl fuel, with sealing gas being a unique form of swirling gas. This gas regulates the flow rate at different cutting speeds. When you stop to inspect your work, the flame intensity reduces.

This cooling mechanism allows for accurate cut even underwater through the prevention of water from entering the torch nozzle.

Plasma Cutter Gas and Your Options

Plasma Cutter Gas and Your Options

Now that you know the type of gases used in plasma cuts, you may wonder – what gas does a plasma cutter use? This is an open-ended question that is answered in different ways by different fabricators.

Typically, hydrogen, pure air, oxygen, nitrogen, and argon are the most common gases used in plasma cuts. Most of these work well cutting thin sheets of half an inch thick. However, when the plate thickness increases and the metal configuration becomes complicated, fabricators usually use a combination of two or three of these gases to enhance their production.

The most common metals conducive for plasma cuts include mild steel, stainless steel, etc. Cutting aluminum is also among the typical uses of a plasma cutter. Depending on the chemical characteristics of the materials under manipulation, their thicknesses, as well as the desired cut dimensions, different gas combinations are used to produce perfect incisions at a faster pace.

Fuel usedCut surfaces
Main gasSecondary gasStainless steelAluminumMild Steel
Argon-HydrogenNitrogenExcellent cuts in a thickness greater than ½’Excellent cuts in a thickness greater than 1/2”Not effective

Cut surface is rough and charred

AirAirGood cut surface Fast cut speed

Easy to use

Good cut surface

Fast speed

Economical

Perfect Cuts

Fast speed

Economical

OxygenAirNot recommendedExcellent cut quality

Fast cut speed

Very little debris

Not recommended
NitrogenAirGood cut surface

Longer part lifespan

Good cut surface

Longer part lifespan

Rougher cut surface

Creates some cut filaments

Longer part lifespan

NitrogenWaterExcellent cut surface

Longer part life

Excellent cut surface

Excellent part life

 

Fair cut surface

Some debris release

Excellent part life

NitrogenCarbon dioxideExcellent cut surface

Longer part lifespan

Excellent cut surface

Longer parts lifespan

Fair cut surface

Release some filaments

Excellent parts life

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1. Air

Pure air is useful in plasma cuts. It’s readily available and offers an economical use since it can still work as either the main gas or secondary fuel source of plasma combustion.

A significant advantage of using compressed air to fuel plasma cut is it its economy. This gas is cheaply available. Storing it is also cheap since it’s captured in a compressed form. Further, it works on both the aluminum and stainless steel metals.

Working with air is comfortable and clean since it doesn’t leave many particles in its wake.

Benefits

  • Can cut stainless steel, mild steel and aluminum well
  • Cheap to harness and store
  • Release no chippings while cutting
  • Useful in thin sheets with smooth and shiny surfaces

Disadvantages

  • Weak torch – can’t make deep incisions greater than ½”
  • Air plasma works well on thin metal surfaces and is very economical.

2. Oxygen

Oxygen offers the best plasma cutting option when you are dealing with mild steel. Using oxygen produces a high intensive flame that makes cutting a thick plate easy and fast.

Benefits

  • Oxygen is in plenty
  • Easy to use
  • Can work in combination with other secondary fuels
  • Ignites very intense flames

Disadvantages

  • The high heat makes working with softer metals hard.

3. Oxygen (O2)/Air

When oxygen is combined with pure air as a secondary fuel its plasma flame stability increases. It also performs well in thick mild steel cuts. The cut precision is high, and it leaves very little cut debris.

However, it doesn’t work on filmy and shiny surfaces. Hence, it’s ineffective and wasteful in stainless steel and aluminum projects.

Benefits

  • Oxygen is readily available
  • Cheap to transport and store
  • Economical to use
  • Effective in thick, coarse metal sheets like mild steel

Disadvantages

  • Poor cuts in light materials like aluminum and stainless steel

4. Argon

Argo is a rare gas, so it’s expensive. However, it’s an inert gas, meaning that it doesn’t react with metals when cutting them. Therefore, its effectiveness in plasma cutting is indisputable.

Benefits

  • High kinetic energy for excellent dissolution or melt of cut filament leaving the surface smooth.
  • Low ionization produces an excellent plasma beam
  • Can use many different secondary gases – pure air, carbon dioxide, and water
  • Effective in thin sheets with smooth and shiny surfaces

Disadvantages

  • Argo can’t work alone due to low conductivity

5. Hydrogen

Hydrogen is an excellent thermal conductor. Besides, it has suitable properties to cool hot surfaces quickly. Hence, it’s useful for cutting light metals such as aluminum and stainless steel. However, hydrogen must combine with other gases to create a high-intensity plasma flame.

Benefits

  • Hydrogen has an excellent conductivity
  • Cheap to harness and store
  • Can combine many different secondary gases – pure air, carbon dioxide, and water
  • Hydrogen dissociates at high temperatures, making excellent cooling on smooth and shiny surfaces

Disadvantages

  • Low atomic weigh restricts great kinetic energy.
  • Can’t work alone in plasma cuts

Due to the contrasting properties between hydrogen and argon, they form an excellent combination of plasma flame production.

6. Argon-Hydrogen (n2)

When you desire to cut shiny metal plates that are thick, argon and hydrogen combination offers the most natural choice. The gas mix emits the most intense plasma energy capable of ripping thick sheets.

Typically, the argon-hydrogen gas mix ratio is 3:2.  During the water injection plasma cuts, this gas easily tears a 6” thick stainless steel plate. It can also utilize nitrogen as the control gas.

Benefits

  • Produces a mighty flame.
  • Has intense heat capable of ripping thick sheets.
  • Can use nitrogen as a secondary gas for cleaner cuts
  • Effective in thick metal plates with shiny surfaces

Disadvantages

  • Argon is a rare gas, hence expensive
  • Cause chipping and filling during cuts
  • Does work well with mild steel
  • Only works in a controlled environment

When you need to cut a thick sheet of stainless steel or aluminum, then consider an argon-hydrogen combination. Even though you will have some filling littering your worktop, you still get the tough job done quickly.

7. Nitrogen

Nitrogen is abundantly available in the atmosphere. For plasma cutting, this gas provides the most popular option and use in virtually all plasma cuts. It works best when dealing with thin and malleable sheets such as stainless steel and aluminum.

Nitrogen gas is very economical in plasma use, yet it still offers a high level of precision cuts.  Unfortunately, this gas doesn’t perform well in thick plates measuring over ½” inch. In such a case, nitrogen is augmented with argon as a secondary fuel.

Finally, nitrogen is versatile in a plasma cutting process. It can act as either the main gas or secondary gas during plasma cuts.

Benefit

  • Nitrogen is plenty in the atmosphere
  • Cheap to harness and store
  • Can use many different secondary gases – pure air, carbon dioxide, and water
  • Effective in thin sheets with smooth and shiny surfaces

Disadvantages

  • Weak torch – can’t make deep incisions greater than ½”

8. Nitrogen (n2)/co2

When carbon dioxide is the secondary gas, the cutting speed of nitrogen gas plasma significantly improves. The finished surfaces are also better while the cut piece lasts longer.

Benefits

  • Improved cutting speed
  • Enhanced precision
  • The finished product is shiny
  • The accuracy makes the part lasts longer

Disadvantages

  • Very expensive compared to other secondary gases.
  • Transporting it is difficult
  • Storage is expensive and delicate

You can use this combination when the metal plate you are working on is thicker than ½”. It’s powerful and delivers a neat, clean and clear cut fast. However, it costs more to perform plasma cut using this gaseous mix.

9. Nitrogen (n2)2/Air

Nitrogen gas can also harness pure air as its secondary gas for certain applications. This combination makes it a useful plasma fuel.  When air combines with nitrogen, the resultant plasma torch becomes more intense.

Benefits

  • Air is cheaply available
  • Air is easy to collect and store
  • Economical during useless consumption during cuts
  • Air enhances the cutting strength of nitrogen hence performs cuts on thicker metals.
  • Effective in thin sheets with smooth and shiny surfaces

Disadvantages

  • Pure air needs purification which also increases its purchase cost.

10. Nitrogen (n2)/h2o

Water is yet another secondary gas that can support nitrogen gas to perform plasma cuts. Water is abundantly available and easy to handle, making it a preferred combination of many cuts. It lowers the overall cost of plasma cuts.

When you perform this combination of plasma cuts on aluminum and stainless steel, it produces a glossy finish.

Benefits

  • Affordable
  • Easy to collect and store so cheaper storage expenses

Disadvantages

  • Bulky liquid
  • Requires a special nozzle to protect against water abstraction by the plasma head
  • Can’t make deep incision greater than ½”

When you are welding or cutting under the water or using a water table, this gas mix produces the best results. It’s particularly useful in cuts on stainless steel and aluminum plates.  Using it leaves smooth cut edges.

From the above, what kind of gas does a plasma cutter after you’ve set it up is dependent on the type of metal you want to cut, the cutting speed as well as the cost of undertaking such a cut.

Certain processes require that you use a water table, meaning that you have to use a plasma cutter gas that incorporates water as a secondary fuel. When you want to cut thin sheets of aluminum and stainless steel quickly and cheaply, then nitrogen and oxygen are the main fuels you should consider for plasma cuts.

However, when your cut materials are thick and coarse mild steel, then hydrogen and argon offer the best plasma cut properties. The level of precision and cost implication will help you select the most useful secondary gas for such projects.

In conclusion, just remember that you need an excellent and durable cut done quickly and at a reasonable price.

About the author

Brent Butterworth

A Professional Woodworker & Custom Furniture Builder

Brent lives in Wisconsin and is a woodworker, custom cabinetmaker, interior consultant, and a freelance writer who got the opportunity to write several magazine articles for different publications on home improvement and woodworking. He’s always amazed at the depth and breadth of woodworking all over the globe, and feels proud to be a part of this great effort. Brent has built everything one can imagine, from unique art furniture to different types of home furniture to canoes and even a sailboat.

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