Plasma cutting is an established method of metal profiling that has been available to engineers for decades. It emerged in tandem with the plasma arc welding (PAW) technique in the 1950s, and the two remain closely linked today. In this blog post, Masteel aims to offer a comprehensive overview of plasma cutting, from its earliest iterations to its modern capabilities.
What is Plasma?
Plasma is described as the fourth state of matter (solids, liquids, gases) in which an ionized gas species becomes highly conductive to electricity. It is typically measured in Kelvin (K), as consistently high temperatures are required to sustain the plasma’s characteristic ionization. This relationship between conductivity and temperature is fundamental to the plasma cutting process.
How Does Plasma Cutting Work?
A plasma cutter uses a stream of compressed gas (air, nitrogen, argon, etc.) and a consumable wire electrode as the two primary feedstocks of the cutting process. The electrode sends a high electrical charge through the gas, raising its temperature to the point of ionization to generate extremely hot plasma (~20,000°C). This plasma is directed through the cutting tip to create a highly focussed beam, with velocities approaching the speed of sound.
The ultra-hot jet of a plasma torch rapidly melts through metal, while an additional stream of shielding gas surrounds the cutting point to remove molten material and preserve process precision.
Limitations of Plasma Cutting
Plasma cutters fundamentally rely on electrical conductivity to function, which makes profiling insulating materials impossible. It is currently limited to cutting conductive metals like stainless steels and aluminum. Additional safety training is also required to operate plasma cutters as they generate fumes, gases, noise, and ultraviolet (UV) radiation. Experienced professionals should always be equipped to handle these process by-products.
Benefits of Plasma Cutting
Plasma cutting has found widespread use in small- and large-scale metalworking applications alike, from raw sheet metal profiling to scrapping operations. As a result, being unable to cut insulators is rarely a limiting factor for the technology’s primary markets. Plasma torches can cut thin and thick sheet metals alike (<76mm) for both low and high alloy steels and are generally available in large industrial CNC formats for large cutting areas.
Brief History of Plasma Cutting
Although plasma cutting is now entrenched in the metalworking sector, the process described above was only developed in the mid-1950s. Early efforts to generate ultra-hot plasma jets were blighted by poor cutting speeds and quality, alongside poor efficiency. The first consumables included high-density tungsten, which readily reacted with oxygen, significantly reducing its service life. Engineers aimed to overcome this using a liquid turbine, which injected water into the torch to increase arc stabilization and reduce the electrode degradation.
A series of innovative steps forward were taken throughout the ‘70s and ’80s, practically transforming the technology into the accessible method of metal profiling that we are familiar with today. Modern innovations are even considering how to exploit plasma cutting to profile insulating materials, a market segment currently monopolized by laser cutting.
Plasma Cutting Services from Masteel
Masteel provides a robust plasma cutting service for stainless steels and chemically-sensitive metals that are unsuitable for oxyfuel processing. We can produce surgically-precise, large-area metal sheets for a broad range of application areas.