Comment: New developments widen the versatility of plasma cutting

Technological advancements are commonplace in this day and age, with manufacturers constantly devising new products in order to stay ahead of competition. This is the same with plasma metal cutting systems.

The first of such equipment was made available in the 1960s. Since then, technological advancements have enhanced the capabilities of plasma cutting, earning it a reputation of being easy to use on virtually any metal type, and of being highly productive as well.

The countless plasma cutting systems that are employed around the globe today indicate that plasma is now a universally accepted metal cutting process with an incredibly wide range of applications. But while the technology had already been commercially viable for the past five decades, it wasn’t until the last 10 to 15 years that the market witnessed engineering breakthroughs that truly boosted the performance of plasma cutting.

Before exploring one of the most recent developments, let us first take a look at the three plasma technologies – air, conventional mechanized and high definition plasma – that are most widely used in the market today.

Air Plasma

Air plasma systems are primarily designed for manual cutting applications. The power levels of these equipment range from 12 to 120 amps, and even at the lowest output level, air plasma is able to cut materials that are 0.32cm thick. Most of these rely on an inverter power supply technology, allowing them to be portable.

Machine torches are also compatible with air plasma systems, which have electrical interfaces that allow for mechanized cutting applications.

 

 

 

 

 

 

 

 

Air plasma systems, though primarily designed for manual cutting applications, also have electrical interfaces that allow for mechanized cutting.

Conventional Mechanized Plasma

Unlike air plasma, conventional mechanized plasma systems are available only with machine-mountable torches, and have more complex interfaces in order to provide better performance when used together with computer-numeric controls (CNC).

Such plasma equipment have output levels ranging from 130 to 1,000 amps, and are designed for high productivity with mid-level tolerances, as well as for cutting non-ferrous materials as thick as 15.9cm. As a result, mechanized plasma is widely utilized in heavy equipment manufacturing operations, shipyards, and steel service centers.

Conventional mechanized plasma is designed for high productivity with mid-level tolerances, as well as cutting non-ferrous materials.

For the most part, this class of plasma systems requires an astute operator as arc voltage, gas flows and pressures, amongst other parameters, must be correctly defined and carefully monitored in order to produce the best and most consistent cut quality. This is because power levels, material thickness, and torch consumables change throughout the process.

High Definition Plasma

Engineers are constantly in the pursuit of enhancing the cut quality, cut speeds, power levels, operating costs and ease-of-use of plasma systems. Within the last two decades, a new category – high definition plasma – emerged as a result of much research and development.

This class first debuted in the early to mid-1990s and is one of the key developments in the history of plasma cutting, besides the introduction of the process itself in 1957 and the introduction of oxygen plasma cutting for carbon steel in 1983.

The new high definition plasma technology essentially works by forcing the plasma arc through a smaller nozzle orifice. Such equipment take advantage of the laws of high temperature physics, allowing for cleaner cut edges while maintaining acceptable torch consumable (nozzle and electrode) life.

The earliest high definition plasma systems were limited in amperage (70 amps maximum) and thickness capacity (0.95cm thickness for steel), and were by today’s standards considered difficult to handle. They required an expert machine operator to monitor and adjust multiple parameters that affect cut quality. But over the years, high level engineering efforts by major plasma cutting system manufacturers have lowered operating costs and improved consumable life, cut quality, and speeds. Some of these have also proven to be very versatile, with the ability to production pierce 75mm-thick metals, sever 160mm-thick ones, and easily cut thin metal — including gauge — with just a single torch. For these reasons, high definition plasma systems are now metal fabricators’ primary metal cutting systems of choice.

Some high-definition plasma systems can production pierce 75mm-thick metals, sever 160mm-thick ones, and easily cut thin metal with a single torch.

A Recent Technological Update

In recent years, many breakthroughs in cut quality, consumable life, productivity, and ease-of-use of mechanized plasma cutting were based on ‘external systems’ in the process, such as torch height controls (THC) and computer-aided manufacturing (CAM) software. Although these so-called external factors are known to affect mechanized cutting operations in terms of cut part accuracy, operation costs, and throughput, the parameters associated with each of these systems were ultimately all controlled by system programmers and machine operators. In other words, even with the most advanced plasma equipment, cut quality and consistency are still dependent on the operator’s expertise and experience.

What the industry really needed was greater consistency in the control of dozens of critical operating parameters. Ideally, all components of a mechanized cutting process should be able to work together more seamlessly and efficiently to produce consistent results, regardless of programmer or operator expertise. With this clear objective, plasma system manufacturers went to work to develop a better high definition plasma solution. System engineers collaborated with suppliers of CNC, THC and computer-aided design (CAD) software (also known as nesting software), and years of research and development gave rise to a new technology – the integrated plasma cutting solution. This innovation utilizes the entire suite of mechanized plasma system components – power supply, CNC, nesting software and THC – to fully automate and coordinate the functions that affect cut quality.

Unlike conventional mechanized plasma, the integrated plasma cutting solution relies less on operator intervention. Using compatible nesting software, the system is able to accept and, where necessary, convert most commonly used 2D and 3D CAD/CAM file formats to geometrical shapes for nesting. The features of the part drawing, such as profiles and bill-of-materials, which include material type and thickness, are then analyzed. Next, the system uses the findings to nest the parts necessary for cutting. These results also help determine the best lead-in/out technique, kerf, cut speed, amperage, gas type, piercing methodology and timing, etc. The integrated plasma cutting solution also sets all of the cutting parameters that are normally controlled by the operator at the machine, by consolidating special commands in the CNC output file. Results include bolt-ready holes without tapers and dings, maximum material utilization, and high quality cut parts that are consistently achievable.

One major advantage of an integrated plasma cutting solution is its ability to produce bolt-ready holes without tapers and dings.

There are still greater benefits that can be achieved with an integrated plasma cutting solution. With a suitable THC, torch motion routines are automatically programmed, thereby enhancing cut quality, reducing cut-to-cut cycle time, and maximizing consumable life. These ultimately work to heighten productivity and reduce operating costs.

Conclusion

The new class of high definition plasma systems, equipped with the right mix of CNC, THC and CAM software systems, truly enhance the metal cutting process while requiring minimal operator intervention. An integrated plasma cutting solution improves cut part accuracies, reduces operating costs and increases productivity. All of these are repeatable with the simple push of a button. And because expertise needed for the cutting and nesting process is in-built within the system, less time is required to train operators, and on-the-job experience becomes a much smaller factor in determining cut quality.

Plasma cutting technology has marked improvements since it was first introduced in 1957.  With air, conventional mechanized and high definition plasma, end-users have a wide array of systems to choose from for various cutting applications. The introduction of the integrated plasma cutting solution is notable because the metal cutting process, though made simpler, now produces greater benefits in terms of cut quality, productivity and cost.

But the sky is the limit, and innovations in plasma systems do not end here. In years to come, the industry will most definitely see greater improvements and even more advanced engineering solutions to better serve companies’ evolving metal cutting needs.

 

About the author: Jim Colt is the strategic account manager at Hypertherm.

[This article first appeared on Factory Equipment News (FEN), another Reed Business Information publication.]