The Bizarre History Of Plasma Cutting

As the winds whirled about and the seas rocked their boat with a chorus of thunder, sailors used to watch the top of their ship&#;s mast. They hoped to see a strange glowing light above, a good omen that the storm was about over. This phenomenon was known as St. Elmo&#;s fire. Interestingly, that same good omen is how modern plasma cutters work. You see, the heavily charged air from the storm would interact with the mast of the ship, creating a ball of plasma &#; the same plasma we use to cut through metal today. In this article, we'll explore the origins of plasma cutting, from the discovery of plasma to how the powerful force of electrical energy was harnessed into a welding tool.

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Who Discovered Plasma?

While humankind has been exposed to plasma since the beginning of time, real understanding only started about a century ago. The first real recognition came from Sir William Crookes, a scientist with a curiosity as large as his incredible mustache. At the time of his discovery, Crookes called the strange substance &#;Radiant matter.&#; Interestingly, the name &#;plasma&#; was given to this 4th state of matter much later in because it looked like the plasma in our blood.

What Is a Plasma Cutting Machine?

Fast forward to , when James Browning and Merle Thorpe began utilizing plasma as a method for heating metal. This innovative approach originated from the US Space program, where plasma was initially employed to simulate the extreme heat conditions experienced by rocket capsules during reentry. As early as , Browning and Thorpe developed the first plasma torch, capable of generating an arc jet with temperatures exceeding twice that of the sun's surface. Their pioneering efforts led to the establishment of Thermal Dynamics, a company that remains prominent in the field of plasma-cutting technology.

Interestingly, while it was James and Merle who invented plasma cutting, they didn&#;t secure the first patent on plasma cutting, which was granted to Dr. Robert Gage at Union Carbide. In fact, Union Carbide would hold the patent for the next 17 years.

While they might not have roped in the first patent, Thermal Dynamics soon became one of the biggest players in plasma cutting equipment and research, securing patents on several improvements. Early machines were quite an investment, mostly geared towards large factories and nothing like the small, handheld versions we have today.

Understanding Plasma Cutting

A plasma-cutting machine utilizes a high-velocity jet of ionized gas (plasma) to cut through electrically conductive materials such as steel, aluminum, brass, and copper. The plasma-cutting process involves passing an electric arc through a gas (typically compressed air), transforming it into plasma. This superheated plasma, directed through a narrow nozzle, creates a focused and precise cutting flame that can easily slice through thick metals.

How Hot Can a Plasma Cutter Get?

A modern plasma cutter can reach extremely high temperatures, typically between 20,000°C (36,032°F) to 30,000°C (54,032°F). This is significantly hotter than the sun's surface, which has a temperature of about 5,500°C (9,932°F) at its visible surface. The intense heat generated by a plasma cutter is due to the ionization of gas (plasma) passing through an electric arc, creating a focused and powerful cutting flame capable of melting and severing electrically conductive materials like metal with precision and efficiency.

Applications of Plasma Cutting

Initially, plasma cutting machines were large-scale industrial tools, primarily used in factories for heavy-duty metal fabrication. Over time, advancements in technology have led to the development of smaller, more portable plasma cutters suitable for various applications:

• Metal Fabrication:

  Used extensively in metalworking industries for cutting, gouging, and piercing operations.

• Automotive Repair:

  Ideal for precise cutting of automotive body panels and frames.

• Construction:

  Used in structural steel fabrication and on-site metal installation.

• Artistic Metalwork:

  Popular among artists and sculptors for creating intricate metal designs.

Enter Hypertherm

In , another huge name in the industry got its start when Dick Couch and Bob Dean founded Hypertherm. They had developed a way of radially injecting water into the plasma arc. This significantly compressed the arc, creating a more concentrated heat column that resulted in a much cleaner cut.

In the s, Thermal Dynamics released the PAK 40, the first plasma cutter released as a single unit. It sold for $4,900 (or $33,400 in today&#;s money). And while improvements continued to be made, plasma cutters were still out of reach for most welders. In , Thermal Dynamics&#; PAK 5 sold for $2,950 ($9,880 in today&#;s money). While this was a significant difference, the PAK 3 brought an even more drastic change as the first handheld plasma cutter ever mass-produced.

In , Hypertherm introduced its own handheld unit, the MAX 40. At this time, the plasma market was still quite niche, and the MAX 40 was considered a success, having sold 1,000 units in its first year. However, that all changed at the end of the decade.

The Plasma Market Explodes

In the s, the plasma market exploded, growing by fifty times. During the next 20 years, plasma cutters became increasingly available to the everyday welder. While advances allowed plasma cutters to be more powerful, less costly, and more portable, there were several issues. Plasma cutters became somewhat controversial, with many welders feeling this &#;new, fancy cutter&#; had several problems compared to older cutting methods like Oxy Acetylene or a good, old-fashioned grinder.

Shop Plasma Cutters at Welding Supplies From IOC

Today, plasma cutters available to the public have made extensive strides. While some welders are still a little weary, plasma cutters have become common equipment, capable of creating cleaner cuts than any other type of machine. If you haven&#;t seen the capabilities of modern plasma cutters today, you owe it to yourself to check out how much they&#;ve improved. Check out our store to shop the best plasma cutters on the market, as well as other top welding equipment.

Plasma cutting has come a long way since it was first developed in the late s by engineers at Union Carbide Corp. Today it is one of the most widely used metal plate cutting processes for a large variety of industries.

Early plasma cutting systems (see Figure 1) were used primarily for cutting stainless steel and aluminum plate from 0.5 to more than 6 in. thick. These systems, primitive by today&#;s design standards, were the most practical method for cutting heavy nonferrous plate. Most were mounted on XY cutting pantograph-style machines that used either photo-cell tracers to duplicate large black line engineering drawings of the parts to be cut, or a magnetic tracer to follow the path of a steel template.

Engineers continuously worked on the process throughout the s with the goal of improving cut quality and the life of the consumable nozzles and electrodes in the cutting torch. Plasma began gaining momentum during this period as the process improved and as users became aware of its ability to cut complex shapes in nonferrous materials at very high speeds.

In radial water injection was introduced. This patented nozzle technology used pure water injected radially around the plasma jet to constrict the arc, increasing its energy density while improving nozzle cooling and thus allowing faster cut speeds, higher-quality cuts, and the ability to cut carbon steels at speeds four to six times faster than an oxyfuel cutting process.

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At about that same time, XY coordinate drive cutting machine technology was being improved. Microprocessor control technology started to become the brains of the XY motion control machines, allowing for better accuracy, higher cutting speeds (necessary for the new-technology plasma systems), and higher levels of automation and productivity on the shop floor.

Through the s plasma cutting technology replaced many oxyfuel-based steel cutting applications from 0.25 to 1 in. thick, while still maintaining its stronghold on the stainless and aluminum markets. While plasma could cut steel thicker than 1 in., the oxyfuel process still was a lower-cost alternative for heavier steel plate.

Timeline of Major Engineering Breakthroughs

With the baseline of plasma&#;s early history established, let&#;s take a look at some of the major engineering breakthroughs with this technology:

The plasma cutting process was developed and patented by Union Carbide as an extension of the gas tungsten arc welding (GTAW) process.

- Several new developments were completed in consumable design, and the dual flow torch was designed to help improve consumable life and cut quality on nonferrous materials.

The water injection process was commercialized. This process allowed for cutting with clean, square-cut edges and faster speeds, as well as cutting of carbon steels with acceptable cut quality.

- The water table and water muffler, designed to provide fume and smoke control, debuted. Automated arc voltage-based height controls for more consistent cut quality and longer consumable parts life emerged.

- Oxygen-based plasma cutting systems that helped improve edge squareness and edge metallurgy (softer, weldable edge) and allowed for cutting carbon steels at lower power levels and higher cut speeds (see Figure 2) were introduced.

- Many developments in the air plasma cutting process allowed for better portability and lower power levels for hand cutting and mechanized thin-sheet cutting.

Better power supply designs using pulse width-modulated, current-controlled outputs were developed. Some systems started to use lighter-weight, smaller inverter technology power supplies suitable for portable, hand-held plasma systems.

Long-life oxygen process technology was introduced. This was essentially a microprocessor-controlled method of controlling plasma gas ramping pressures as well as power supply output amperage. It helped increase typical oxygen plasma consumable parts life by four to six times; improved parts consistency; and helped lower the cost of plasma cutting.

High-definition plasma, a technique that required the previous long-life oxygen technology to implement, was developed. This process allowed for a new nozzle design that increased the energy density of an oxygen plasma arc by as much as four times, allowing for squarer, cleaner cuts in all material thicknesses.

Automated gas flow control systems emerged. They interfaced digitally with the machines&#; CNCs. These gas flow controls eliminated some of the potential for machine operator-related errors in setting parameters for the cutting process.

- Many developments occurred relating to improving cut quality and productivity and automating the many process cut parameters. These included integrated plasma, a system that closely coupled the CNC, the plasma power supply, the gas flow control, the CAM software, and the height control system to automate the process. With this expertise built into the system, the machine operator&#;s job became much simpler, and the process relied less on operator expertise.

Recent Technology Developments

In the last seven years, developments in plasma cutting technology have come at a fast pace. The latest revision on high-definition machines is their full integration with the CNC machines they are coupled with. New CNCs have touchscreen accessibility, minimizing the number of buttons involved in operating a plasma cutting machine and making operation as simple as almost any Windows®-based software. Operator training has been simplified on even the largest, most complex CNC plasma cutting machines.

The operator&#;s job also has been made easier with improvements in auto-calibrating height control functionality. The operator does not need to make adjustments as the consumable parts in the torch wear out.

Hole cutting has been improved with a large database of information in the CAM software that automatically recognizes CAD features and implements the best possible cut path and plasma cutting parameters, including on-the-fly shield gas changes that nearly eliminate the normal taper found in plasma-cut holes on steel (see Figure 3). This process is transparent to the machine operator and system programmer, eliminating the need for them to be experts.

Improvements in cut-to-cut cycle times have been incorporated into CAM software. The software automatically recognizes areas of a full cutting nest (multiple parts) and modifies the traverse time, torch retract time, and gas preflow time to decrease production times and improve product throughput.

Nesting software now applies the lead-in points in the most effective way to avoid traversing over areas prone to collisions with previously cut parts.

Improved plate beveling software has simplified the integration and operation of a bevel head with XY CNC cutting machines. This advancement, again associated with the system&#;s CAM software, saves much of the programmer/operator trial-and-error testing that has always been necessary to hold the best tolerances on plate edge beveling applications, such as weld prep.

Very new vented nozzle and gas mixing technology has helped improve stainless steel edge quality. Edges are squarer, shiny, and weldable.

Air plasma cutting systems from the major manufacturers also improved dramatically in terms of cut quality, consumable life, and duty cycles. These systems, primarily designed for portable and in-shop hand-held cutting applications, now are available with quick-change mechanized torches and interface easily to a variety of lower-cost CNC machines. Systems are available from a 30-amp, toaster-sized unit that operates on 120-V household current to sever materials up to 0.5 in. thick, to a 125-amp, 100 percent duty cycle industrial unit that can sever 2.25-in. materials. Both portable systems can be used with a hand torch or can be mechanized for a variety of automated cutting applications.

Industrial mechanized systems typically are 100 percent duty cycle, available with machine torches, and designed to use a variety of compressed gases to fine-tune the cut quality for different materials. These systems are available in various sizes and capacities from 130 to 800 amps.

Many other advances have been made to improve reliability, performance, consumable life, cut quality, and ease of use since the first plasma system was created. The process shares the cutting market with laser cutting, abrasive waterjet, and oxyfuel cutting, all of which deliver accuracy, productivity, and long-term cost-effectiveness when used for the appropriate applications.

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