Plasma cutting technology was first developed in the 1950s and gradually became a mainstay in manufacturing and metal fabrication. The 1990s marked a turning point with the introduction of high definition plasma cutting (HD), which significantly improved precision, cutting speed, and edge quality compared to earlier systems.
Early plasma cutters could only handle steel up to around 6 mm thick due to power and cutting capacity limitations. Modern HD plasma systems, however, are far more versatile — capable of cutting much greater thicknesses while still delivering exceptional accuracy and a high-quality finish.
HD plasma is sometimes marketed under other names or taglines. For example, Hypertherm refers to its latest generation of XPR power sources as XD to highlight the extended definition and performance improvements over traditional HD systems. Regardless of the branding, the principle is the same: a finely focused, high-velocity jet of ionised gas (plasma) cuts through conductive metals such as steel, copper, brass, and aluminium with remarkable consistency.
High Definition Plasma Cutting Machine Basics
The plasma cutting of conductive metals is achieved by sending a gas (sometimes simply air, but also possibly oxygen, hydrogen, nitrogen, argon or a combination) through a nozzle at high pressure, where it is turned into plasma by an electric arc that generates an extremely high temperature. Once the plasma arc comes into contact with a conductive metal, the metal becomes molten along a prescribed line so that the metal is cut. The speed and intensity of the plasma arc then blow away the molten metal to leave a clean cut.
Initial systems were limited in the thicknesses of metal they could cut, but advances in technology have increased the cutting capacity as well as the speed and accuracy. Nowadays, a high-definition CNC plasma cutting table is easily capable of cutting mild steel to a depth of 64 mm at 460 amps or aluminium to 150 mm at 800 amps. These modern machines are also easier to use, provide higher productivity and have a lower cost per cut.
High definition plasma cutters differ from standard CNC machines in that they have much more control over the plasma arc, enabling it to be better focused to produce a superior cut quality.
A high-definition plasma cutter achieves better quality and faster cuts due to several enhancements from a standard air shielded model:
- Whereas a standard cutter can run on compressed air or shop air, a high definition version uses a combination of gases such as hydrogen and nitrogen in addition to compressed air. The actual mix will depend on the materials being cut and so can be varied between jobs. It is also possible to have different gases for piercing, cutting and shielding so that a much better definition cut with limited taper is produced.
- The electric arc is started by high frequency, which can also be used for the cutting process.
- The plasma torch has a smaller nozzle that tightens the plasma stream so that cuts have cleaner and more precise edges with virtually no dross. Concentrating the beam into a smaller area effectively produces a cutting tool that is much sharper and does not disturb the surrounding areas of the material to be cut.
- Precise torch height control greatly improves cut precision as well as reduces electrode wear.
- High definition machines generally have higher power output than standard air shielded versions, typically ranging from 200 to 600 amps compared to the lower than 200 amps that is common for a standard plasma cutter.
Enhancements to performance are also helped by improvements to various components that work together to produce high-definition output. These include the movement of the torch and the cutting bed, where the latter must also have the capacity to withstand the extra weight of the thicker materials that can be cut. High definition plasma cutters are able to handle thicker materials with no loss of precision or quality when compared to thinner materials, so they are extremely flexible when dealing with a variety of applications.
Benefits of a High-Definition Plasma Cutter
Using a high-definition plasma cutter has several advantages over a traditional model:
- They are extremely versatile and are capable of cutting all conductive metals, typically stainless steel, mild steel, steel alloys, carbon steel, copper, brass and aluminium. They can be set to cut a variety of thicknesses that are up to 12 mm of steel for an entry-level machine. A mid-range machine can cut steel up to 32 mm thick, while a high-end system with high definition can handle 60 mm of thickness and possibly more.
- A high-definition system will make dramatic improvements to cut performance. With automated CNC software to control the process, cuts will be extremely precise on all types, shapes and thicknesses of metals. Additionally, since the plasma arc is tightly focused, thinner materials are much less likely to warp due to reduced heat spread.
- High definition plasma cutters are very easy to use and have fast cutting times, so productivity overall is increased. They also have lower operating costs than lasers and water jets, and are much simpler to use.
- A CNC high definition system is fully automated in its operation and so requires less operator intervention and is safer to use. Whilst the plasma arc is hot and safety precautions are necessary, it does not need to be covered when operating, as a laser beam does.
- Although a CNC plasma cutter involves a significant initial investment, a basic package can cost less than one-third the price of a laser cutter or water jet, and running costs are also significantly lower due to the greater durability of components. A high definition cutter will therefore repay your investment much quicker than other types of cutters and is a more practical purchase for small and medium-sized companies.
Is a High-Definition Plasma Cutter the Best Option?
If you need to cut a variety of thick, conductive metals quickly and with a high degree of precision carried out consistently, a high-definition plasma cutter is likely to be the best option. However, many fabrication shops and other businesses in Australia will normally cut metal that has a maximum thickness of 32 mm, often much less. In these cases, a standard plasma cutter at a much lower cost will be quite adequate and produce exactly the cuts you need.
Plasma cutting was originally developed to cut steel and non-ferrous metals, and is still the ideal choice for these metals. Alternative cutting methods include oxy-fuel and laser. Plasma cutting is, however, faster at cutting thinner materials of up to 25 mm thick and is more efficient with non-linear cuts.
An oxy-fuel cutter tends to be more efficient with heavier section steels up to 300 mm thick, cutting them faster and using less power. However, the immense heat it produces can cause thinner metals to warp, so plasma cutting is better for these. Additionally, since oxy cutting burns through metals, it cannot be used for metals such as stainless steel and aluminium that do not support the oxidation process.
Choosing the Most Suitable Type of Cutting System
A high-definition plasma cutting system creates precision cutting by concentrating more energy into a smaller area, and so increases plasma density. The outcome is less bevel, a narrower kerf and a lower level of top edge rounding. It is also extremely fast, capable of achieving cutting speeds of up to 2.5 metres per minute — or even 3.8 metres per minute in situations where ultimate cut quality is not the top priority and the cut edges are long and straight.
A high definition system also has longer-lasting consumables, possibly between 1,300 and 3,700 arc starts or more, while cut accuracy can be ±0.01 to 0.05 inches with kerf widths no more than 0.05 inches. Bevel cutting technology for plasma cutters now means that weld preparation time and cost are reduced.
Plasma technology continues to develop so that precision, speed and cost-effectiveness are becoming even better, particularly for high definition models. Other cutting technologies are also increasing their capabilities, so the choice of cutting methods becomes even broader. Choosing the most appropriate type of cutting can pay immense dividends in terms of productivity and profitability, but it is a complex subject, so the task is not easy.
At Plazmax, we offer a wide range of cutting equipment and have the expertise and experience to design, supply and maintain a system that is exactly right for your business. We also have the willingness to ensure you have the best system, and so we will provide all the help and advice you need. Just get in touch, and we will find the best cutting system solution for your business.