To most people, plasma cutting is a complex process that seems difficult to understand. The term and concept seem too technical for those who have not come across it before – and even for those working in the relevant industries without context about what they are and how they work.
Although it sounds highly technical, the core concept of how plasma cutting works and its utilisation is far more approachable. In fact, this process was developed before laser cutting and is common worldwide.
Plasma cutting is a less versatile way of cutting metal compared to laser cutting, but there are some scenarios where it’s the method of choice. Plasma cutters can only cut through metals that are conductive, like mild steel and stainless steel.
Plasma cutting has found a role in many industries, some you may not even have considered! When you’re making metal fabrication choices, you’ll probably be comparing plasma cutting vs laser cutting to decide which is best for your needs.
Want to find out more about plasma cutting? Read on to learn everything there is to know about plasma cutting and which applications are best for a plasma cutter.
What Is Plasma Cutting?
Plasma cutting is a unique technique used to cut through any type of electrically conductive metal. In plasma cutting, metals are cut using an accelerated stream of hot plasma – at a temperature of above 20,000°C.
Plasma cutting is valued in industrial settings because of its powerful results. In addition, compared with processes like laser cutting and water jet cutting, plasma cutting is cost-effective and budget-friendly when used in certain projects.
The technology was originally developed as an alternative to the traditional oxy-fuel cutting method, rather than as an alternative to laser cutting. Oxy-fuel cutting uses gas or fuels like petrol or diesel to generate heat. Plasma cutting reaches much higher temperatures and therefore cuts metals that oxy-fuel torches cannot.
Since the plasma cutter can produce an extremely hot ‘cone’ for cutting, this method shears through metal as quickly as possible, especially when cutting curved or angled conductive metal sheets.
The process of plasma cutting is usually done using fixed machines. However, it can also be done by hand using a plasma torch, also known as plasma cutters, plasma guns, or plasma arcs. These are commonly used in settings like wrecking yards and allows for spatial flexibility in how these processes are done.
How Does Plasma Cutting Work?
Plasma cutting works by using electrically ionised and superheated gas to cut through conductive metal. The jet of gas is so hot that it can reach temperatures of more than 20,000°C.
The plasma cutting process (or plasma arc cutting) begins when a compatible compressed gas is blown from a focused nozzle to a conductive metal at high speed. An electric ‘arc’ is formed between an electrode (cathode) and the conductive metal (anode).
The arc ionises part of the gas during this stage to create a plasma channel. The current from the cutter’s torch then flows through this plasma. This process produces extreme heat that is hot enough to cut clean through metal. As the arc is constricted by the electrode, which is forced through a water or air-cooled nozzle, a jet of narrow, super hot, and high-speed plasma is formed.
Different nozzles are available for various applications, such as high tolerance plasma arc cutting (or HTPAC).
The gasses needed to power and effectively run a plasma cutter depends entirely on what you plan to cut. Compressed air, nitrogen, oxygen and argon-hydrogen mixtures are commonly found as gas sources for plasma cutters. Still, the ideal gas will change depending on the material type, conductivity and thickness.
Plasma cutting machines are highly powerful but require large amounts of power to operate. As the hot stream is produced, the molten metal is blown away by both the compressed gas and the high-speed plasma.
While not a direct part of the laser cutter, fume control is another essential component of any plasma cutting operation. Because chemical gas and flames are produced and used in the plasma cutting process, poor ventilation and fume extraction can be dangerous to the operator of the machine and the entire workshop. Fume extraction can be air or water-based and can be attached to the machine itself or part of the workshop.
What Are Plasma Cutters Used For?
Plasma cutting can be used in metal fabrication, but is better suited to less precise work on construction sites and salvage yards. The process is also used in manufacturing, auto repair, auto restoration, construction, and scrapping industries.
In design and the arts, plasma cutting can be used by creatives such as sign artists, interior designers, and sculptors. Plasma cutting is also often combined with other metal finishing processes, like powder coating, to achieve industry-level results.
Plasma cutters are no longer only utilised in smaller-scale industrial businesses and for creating artistic pieces. The call for strong and fast cutting of metals of all thicknesses has expanded, and plasma cutters are now found in almost all intensive metal industries like the aerospace, automotive and defence industries.
Where quick, powerful cutting is needed, plasma torches can be a handy tool – however, plasma cutting is less versatile than laser cutting, as it’s only effective on conductive metals. The results are also far less precise than laser cutting, meaning laser cutters are the method of choice for most modern applications.
Read on to learn more about the pros and cons of plasma cutting.
Advantages And Disadvantages Of Plasma Cutting
Like all cutting methods, plasma cutting has its share of advantages and disadvantages. While the pros of plasma outweigh the cons for some applications, it is important to know exactly where this technology falls flat and where it succeeds.
Being aware of the advantages and disadvantages of a plasma cutter may help you decide which is best for your project.
Pros Of Plasma Cutting
Cutting Strength – The main reason plasma cutting has gained tremendous popularity over the years is its power. The method can cut through all electrically conductive metals, including very thick sheet metal. Considering that plasma cutters are often found in the automotive and aerospace industries that deal with large, thick pieces of metal, the relative strength of the cutter is fundamental.
Cutting Speed – A plasma cutter is significantly faster than oxy-fuel torch cutting. In fact, a plasma cutter can be up to ten times faster than oxy-fuel, making it an excellent choice for those wanting to cut down large metal structures with speed. This method is therefore used by wreckers and scrappers to process large quantities of material quickly.
Cons Of Plasma Cutting
Application – Because it can only cut through conductive metals, the applications for plasma cutting are far more limiting. Plasma cutters are also limited to cutting, whereas laser cutters can perform other fabrication tasks like engraving and etching. This is why professional metal fabricators choose to use laser cutters, as they have an incredibly large range of materials they can cut in comparison.
Price – The saying of ‘you get what you pay for’ rings true with plasma cutting. The results of plasma cutting are excellent, but as a result, it’s not a cheap process. Oxy-fuel torches are less powerful but if the extreme heat of a plasma cutter isn’t required to get the job done, many on-site applications can be carried out with this older technology.
Power Consumption – Because a plasma cutter is so powerful, it naturally requires a lot of energy to run. Not only are they more expensive to run because of the higher power consumption, but some metal fabrication companies may not have sufficient energy output to run them safely or at all.
Precision – While CNC technology can be used with plasma cutting to add more precision, many intricate or detailed metal cutting tasks can only be performed with a laser cutter. For tight tolerances, plasma cutting is not a recommended method.
Cut Quality – Plasma cutting produces relatively high-quality cuts, especially compared to oxy-fuel torches. However, as good as plasma cut metal may look to the naked eye, it’s still not the same level of quality and precision as a laser cutter. If quality is a priority, laser cutting will be the best option.
What Metals Can A Plasma Cutter Cut?
Plasma cutting can be used on steel, aluminium, brass, copper, stainless steel, and other conductive materials.
Metals that are not conductive are nearly impossible to plasma cut. Manganese is an excellent example of a metal that is a very poor electricity conductor, making it difficult, if not impossible, to plasma cut. Bismuth and tungsten have the same issue of being poor conductors, making them hard to plasma cut.
Lead can be cut with a plasma cutter, but the process will cause it to splatter and can be dangerous. Tin is similar in that it’s hard for a plasma cutter to work with and will create poor cuts.
The main application of plasma cutting is varieties of steel, including mild steel and stainless steel, as well as niche materials such as cutting Colorbond steel.
What Gas Do You Need For A Plasma Cutter?
Plasma cutters can operate with a variety of different gases, but they aren’t interchangeable, and choosing the right gas is crucial. You’ll need to select the right gas for the application.
Here are some of the gas types used in plasma cutting:
Compressed air is the most commonly used gas for plasma cutting. Usually used for lower current processes, compressed air is compatible with most metals up to three centimetres thick. It is also preferred by those who want an oxidised cut finish on their workpiece.
Another gas that you can use for plasma cutting is Nitrogen. Used for higher current processes, Nitrogen can cut materials with a maximum thickness of seven and a half centimetres. This is the most preferred gas among metal workers because it produces high-quality cuts on most materials.
Metalworkers who want super-fine quality cuts use oxygen for plasma cutting. This gas can work with carbon steel, up to three centimetres thick. Oxygen is preferred by many because it produces smooth cuts on carbon steel. However, when used on stainless steel and aluminium, the cuts are rough and unpolished.
Argon-Hydrogen Mixtures can be used to cut stainless steel and aluminium. Unlike Oxygen, Argon-Hydrogen mixtures produce a polished and clean-cut face. Metalworkers use this gas to work on materials thicker than seven and a half centimetres.
When Were The First Plasma Cutters Developed?
Although plasma cutters are extremely popular nowadays, it’s interesting to note that the system behind this technology was actually born more than half a century ago. The process of plasma cutting was developed in the 1950s.
Plasma cutting is a technology that has been around for over fifty years, and was originally developed as a more powerful alternative to oxy-fuel cutting. Oxy-fuel torches were ubiquitous as the standard method of cutting metal in the early 20th Century, but don’t reach high enough temperatures for some metals. When first introduced, plasma cutting was very expensive and was only accessible in an industrial setting. As the results of plasma cutting have been superseded by CO2 and fiber laser cutting, plasma cutters are more commonly used in less precise industrial settings, like wrecking and scrapping.
Plasma Cutting FAQs
Is Plasma Cutting Dangerous?
Very much like all other cutting methods, plasma cutting comes with its very own risks and dangers. Although many metalworkers say that the process is a lot safer than using more basic tools to cut metals, it is still crucial to take extra caution when using the plasma technique.
When using a plasma cutter, it’s essential to protect both the machine, the operator and the work surface. For this reason, every single person who is part of the plasma cutting process must be appropriately dressed at all times. This means wearing proper eyewear, eye protection, and a face shield is definitely necessary. Using more protective gear, such as leather gloves, aprons, and jackets should be encouraged for added protection.
Is Plasma Cutting Expensive?
Plasma cutting used to be a very exclusive technology. In fact, in the 1980s, the technology was very expensive, and few people knew about it. Today, however, the tides have turned as plasma cutting technology is available to many more businesses and even individual craftspeople. However, the quality and capability of lower-end plasma cutters is very different to those used in industrial settings.
What Is High Tolerance Plasma Arc Cutting?
High tolerance plasma arc cutting is an evolution of plasma cutting designed to be a low-cost option for cutting metals and materials thinner than 12mm. Also known as high definition plasma cutting, plasma constricted arc cutting or fine plasma cutting, HTPAC utilises altered gas flow and nozzles to cut metals and materials thinner than a centimetre with greater accuracy, speed and quality than traditional plasma cutting.
Disclaimer: This article is published in good faith and for general informational purposes only. Kanyana Engineering does not make any warranties about the ongoing completeness and reliability of this information. Always seek specific advice on your metal fabrication project to ensure all variables are taken into consideration.
Graham Dawe is the Managing Director and Works Manager of Kanyana Engineering. With decades of experience in the metal fabrication industry, he is dedicated to keeping Kanyana at the forefront of the sector’s technological growth. Looking beyond the process itself to holistic, integrated CAD, CAM and MRP solutions, Graham believes Australian manufacturing has an enduring place on the global stage. In Kanyana Engineering’s state-of-the-art workshop in Mandurah, WA, Graham delivers an exceptional standard of work for commercial, industrial and government clients alike.