You've likely seen welding before — the bright blue arc as metal is joined together. But plasma arc welding turns up the heat even more, using ionized gas up to 50,000°F to melt metal.
In this article, we'll look at what sets plasma arc welding apart from basic welding methods, the types of projects where it shines, and whether robots can handle this high-precision task.
We’ll cover:
- What is plasma arc welding?
- How does plasma arc welding work?
- What is plasma arc welding used for? (use cases)
- Can plasma arc welding be automated?
Time to get started!
What is plasma arc welding?
Plasma arc welding (PAW) is an arc welding process that uses an extremely hot, focused plasma arc to melt metal. The plasma is created by passing an electrical arc through a gas, like argon or nitrogen, that's been heated to an ionized state.
Unlike standard arc welding, which uses molten electrodes, PAW uses the concentrated plasma flame to melt the metal. This allows for faster welding speeds, less distortion, and the ability to weld almost any metal.
Let’s take a look at what PAW looks like:
- A PAW torch has a tungsten electrode inside a copper nozzle.
- Starting the welding process creates an electrical arc between the electrode and the workpiece.
- This arc heats the shielding gas into a plasma as it exits the nozzle.
PAW offers several benefits over traditional welding methods:
- Higher welding speeds due to the intense, focused heat of the plasma arc. This results in higher productivity and lower costs.
- Minimal distortion of the material around the weld joint due to the focused heat source. This produces high-quality, precision welds.
- Capability to weld almost all metals, including exotic alloys, due to the extremely high temperatures achieved.
- Improved weld appearance and less need for post-weld cleaning. The plasma arc produces very little spatter.
- Easier automation due to the concentrated heat source and faster welding speeds. Robotic plasma welding systems are commonly used in high-production manufacturing environments.
- All-around safety: The plasma arc is contained within the welding torch, so no open flames are produced. This results in a safer working environment.
- Higher-quality welds: The plasma arc produces a very stable, high-energy heat source for precision welding applications that require high-quality results.
- Environmentally friendly: No shielding gasses containing toxic elements are required for plasma arc welding. Only argon and hydrogen are used.
How does plasma arc welding work?
Have you ever wondered how plasma arc welding fuses metal together?
The science behind this process is actually pretty interesting:
- In PAW, a high-velocity plasma jet is created by ionizing gas with an electrical current. This ionized gas flows through the welding torch and is used as the heat source to melt the base metal. The plasma arc reaches extremely high temperatures of up to 50,000°F, easily melting the metal.
- An inert gas like argon or helium is blown through the welding torch at high pressure, then ionized by an electrical arc to create a plasma. The plasma is a highly conductive ionized gas that conducts electric current and generates an enormous amount of heat.
- The equipment needed includes a power supply, plasma welding torch, pressurized gas, and welding filler metal. The plasma torch is where the magic happens, using a high-velocity plasma jet to melt the metal.
- PAW can be automated or done manually. Automated PAW is often used for high-volume production welding, like welding automobile bodies. Manual PAW allows for more intricate welds and is good for joining metals that are difficult to weld.
Arc welding has several useful applications across various industries.
Why? Because its concentrated heat source makes it perfect for welding materials that are difficult to fuse together using conventional welding methods.
Let’s take a closer look:
- The intense heat of the plasma arc allows it to melt thin sheet metals like aluminum, copper, and stainless steel without burning through the material. This makes PAW ideal for applications where minimal warping and precise control are required, such as in the aerospace industry.
Parts like engine cowlings, fuselages, and wing sections are commonly joined using PAW.
- The high temperatures achievable with PAW, often way over 30,000°F, mean that it can melt even the most stubborn exotic alloys used in the aerospace, nuclear, and chemical processing industries.
Materials like titanium, Inconel, and Hastelloy that typically require expensive filler materials and shielding gasses can be welded efficiently using PAW.
- The PAW process lends itself well to automation and robotics. Precisely controlling the plasma arc and welding parameters is easy to program into an automated system.
Robotic plasma welders are used extensively in high-volume manufacturing environments like shipbuilding, automotive assembly, and appliance manufacturing. Automated PAW helps improve weld quality and consistency while increasing productivity.
- In addition to welding, the high-energy plasma arc can also be used for cutting ferrous and non-ferrous metals. The plasma arc cuts through material by melting it away. Plasma cutting is often used to cut plates, pipes, beams and other profiles. It provides a fast, accurate cut with a narrow kerf, minimal warping and smooth cut edge.
Plasma cutting is great for both manual cutting and CNC cutting machines.
Here are some industries where PAW is making a difference:
- Aerospace: Plasma arc welding (PAW) shines in aerospace manufacturing, where components demand extreme precision. It's commonly used for welding parts of airplanes and spacecraft, where every weld has to withstand high stresses and extreme conditions.
- Automotive: In the automotive industry, PAW is very important for joining thin metal sheets with superhuman accuracy. This technique is particularly beneficial for assembling sensitive components in engines and transmission systems, where even the slightest flaw can lead to failures.
- Medical device reliability: The manufacturing of medical devices relies on PAW for its ability to create precise, high-quality seams on small, intricate components. This welding method is often chosen for its clean, controlled process, essential in producing implants and surgical tools that meet the most stringent health and safety standards.
- Tool and die restoration: In the tool and die industry, PAW is the go-to method for repairing high-value tools and dies. Its focused plasma arc allows for detailed work, restoring parts to their original specifications without compromising the tool's material properties.
Energy infrastructure strength: PAW plays a critical role in fabricating tubes and pipes used in the energy sector. Its capability to produce strong, deep penetration welds maximizes the durability and integrity of pipelines and tubes that transport oil, gas, and other substances under high pressures.
