Researchers at the Hefei Institutes of Physical Science in China have successfully extended the lifespan of a plasma torch from a few hundred hours to several years. In doing so, the team has allegedly achieved the world’s longest-lasting plasma torch, a press release said.
The new design extends the lifespan of plasma torches from days to years. Photo: Weiwei Zhao/CAS.
A plasma torch is a device that generates a constant flow of plasma – the fourth state of matter. In this state, matter is superheated, and electrons are ripped away from the matter, resulting in an ionised gas.
This gas can be used to cut electrically conductive materials precisely and, therefore, find use in industrial applications.
Inert gases such as helium, neon, and argon are typically used in plasma torches. Argon mixed with hydrogen is the industry’s most common gas mixture since it is cost-effective and produces the hottest flame and clearest cuts.
How does a plasma torch work?
For the cutting process, the plasma torch forms an arc with the material to be cut. This arc is constricted by a copper nozzle, which has a fine bore.
The fine outlet facilitates an increase in the temperature and velocity of the plasma that emanates from the torch. A plasma torch can reach temperatures of 20,000 degrees Celsius.
The plasma torch’s efflux also helps remove the molten material from the surface. Unlike cutting using oxygen, plasma cutting does not oxidise the metal under process. It, therefore, can be used across a wide spectrum of materials, such as stainless steel, cast iron, aluminium, and non-ferrous alloys.
In addition to cutting, the approach is also used in other fields, such as low-carbon metallurgy, carbon material preparation, and powder spheroidisation.
In all these applications, the cathode gets depleted and needs to be replenished. This limits the lifespan of the torch while increasing the maintenance costs associated with the equipment.
A simple continuous solution
A research team led by Zhao Peng, a professor at the Hefei Institutes of Physical Science, has found a simple and effective solution to the cathode depletion problem.
The work done under the aegis of the Chinese Academy of Sciences developed a continuous feed system for the cathode that can rapidly replenish old, worn-out ones without interrupting the plasma torch.
The design is innovative since it helps overcome not just one but multiple obstacles and hurdles associated with using plasma torches.
“The design overcomes five major hurdles, including conductivity, thermal conductivity, sealing, water cooling, and continuous propulsion mechanism,” said LI Jun, Senior Engineer at the Hefei Institute, who was involved in the work.
Conventional plasma torches typically run for 160 hours. However, with the cathode being continuously fed, this is the least the new plasma torch can do. With their innovation, the team has allowed plasma torches to run for long periods, thereby reducing their downtime and maintenance costs.
“The operation time for plasma torch gas been extended from several days to several years,” according to CAS.
“We have made the world’s longest-lasting plasma torch,” said Prof Zhao in a press release.
This will further improve the efficiency of the process and lead to the development of more industrialised applications of the plasma torch.