11 Main Plasma Arc Welding Advantages and Disadvantages | Plasma Arc Cutting Applications

11 Main Plasma Arc Welding Advantages and Disadvantages | Plasma Arc Cutting Applications

What is Plasma Arc Welding? Plasma Arc Welding Advantages and Disadvantages | Plasma Arc Cutting  |Principles of Plasma Arc Welding

What is Plasma Arc Welding?

Plasma Arc Welding is a liquid state welding technology in which the metal-to-metal junction forms in a molten state with the assistance of heated ionized gases known as Plasma.

Hot ionized gases are utilized to heat the work plates, and the joint is formed using fusion.

Plasma welding has typically been used to join thin sheets with a minimum thickness of 0.1mm, as well as wire and mesh sections. It is employed in the maritime and aerospace sectors.

Plasma arc welding is used to join stainless steel and titanium pipes and tubes. It is an excellent choice for repairing tools and dies.

This welding method is often used to weld and coat turbine blades. Finally, plasma arc welding is popular in the electronics industry.

How does Plasma arc welding work?

Plasma arc welding is an arc welding method in which heat from a constricted arc established between a tungsten/alloy tungsten electrode and the water-cooled (constricting) nozzle or between a tungsten/alloy tungsten electrode and the work is used to generate coalescence.

The procedure makes use of two inert gases, one of which generates the arc plasma and the other of which shields the arc plasma. The metal filler may or may not be used.

Plasma Arc Cutting

If used for cutting, the plasma gas flow is increased, allowing the deeply penetrating plasma jet to cut through the material and remove the molten material as cutting dross.

Plasma arc cutting varies from oxy-fuel cutting in that the plasma process melts the metal utilizing the arc, whereas the oxy-fuel process oxidizes the metal and the heat from the exothermic reaction melts the metal.

Unlike oxy-fuel cutting, plasma arc cutting can be used to cut refractory oxide-forming metals such as stainless steel, cast iron, aluminum, and other non-ferrous alloys.

Advantages of Plasma Arc Welding

1. Torch design allows better control of the arc

The primary advantage of plasma welding is the control and quality achieved in the welded item. The torch design increases the effectiveness arc control and a greater tolerance for in-torch stand-off distance.

2. This method provides more freedom to observe and control the weld

With the torch design, both hands are free to move and the head is available for observation and control of the weld.

The use of technology allows for usages such as remote monitoring and recording of the weld.

3.  Presence of lower levels of spatter

The plasma arc has less spatter than other welding methods, due to its efficient energy consumption.

Also, it doesn’t cause warping in thin metals; there is no need to preheat them.

4.  The higher heat concentration and plasma jet allows faster travel speeds

The arc provides a more focused heat source resulting in a more efficient use of energy.

The plasma jet travels faster compared to the arc wire, thus reducing travel time and allowing for faster welding speeds.

5.  Heat affected zone is smaller compare to GTAW

With the absence of filler metal, there is no energy release at the root of the bead. This results in small heat affected zone and better appearance of the welded zone.

6. Little or no distortion is created during welding

Since there are no filler metals involved, there is no energy release at the root of the bead, thus low distortion to adjacent materials.

Plasma’s high temperature and high heat concentration allow for the keyhole effect. This allows for complete penetration while welding several joints in a single pass.

Disadvantages of Plasma Arc Welding

1.  The initial investment is high

The equipment and torch design are expensive, and the equipment maintenance requires qualified technicians.

Torch failure can be catastrophic to the operator, requiring additional safety equipment for protection.

Plasma welding equipment is highly expensive. As a result, the start-up costs will be higher.

2. It requires training and specialization to perform plasma welding

This requires training and the ability to integrate and operate a specific plasma welding machine. There are no general-purpose plasma machines.

3. Smaller parts can be successfully welded using plasma arc welding

With the technique of forming a plasma arc between two work surfaces, smaller parts can be welded which are not possible with other welding methods.

4. It produces ultraviolet and infrared radiation

The weld is made from the infrared spectrum. However, there are a number of materials that absorb the infrared light and prevent its emission.

Also, welding with this method emits ultraviolet light which can damage or weaken plastics.

5. The single pass process can cause thermal distortion

The single pass process can cause thermal distortion if the heat is concentrated in one area due to the loss of heat through the surface

If the heat is concentrated in one area there will be distortion because of unbalanced heating when compared to a single pass process such as oxy-fuel cutting.

6. The method produces higher noise levels

With the arc plasma and the high speed of travel, it produces high noise levels. The intense noise can damage hearing and is harmful to younger operators.

7. Welding method causes localized melting

The higher heat produced by the plasma arc compared to other welding methods causes localized melting

The local melting can damage the surface of materials that are sensitive to localized thermal shock such as glass and ceramics.

Plasma Arc Welding FAQs

1. What is plasma arc welding?

Plasma arc welding (PAW) is a type of arc welding that is comparable to gas tungsten arc welding (GTAW). The electric arc is created between an electrode (often, but not always, sintered tungsten) and the workpiece.

The primary distinction between PAW and GTAW is that the electrode in PAW is located within the torch’s body, separating the plasma arc from the shielding gas envelope.

The plasma is then driven into a fine-bore copper nozzle, which constricts the arc and causes the plasma to escape at high velocities (nearing the speed of sound) and temperatures approaching 28,000 °C (50,000 °F) or higher.

2. What are the principles of plasma arc welding?

Plasma arc welding is essentially a gas metal tungsten welding extension (GMAW or TIG). Conconsumable tungsten electrodes are typically used in both welding procedures to deliver power to the welding torch and into the orifice gas.

Much of the difference between the GMAW and PAW welding processes can be attributed to the orifice gas. The design of a PAW torch allows orifice gas to accumulate in a chamber at the torch’s tip.

The orifice gas is heated to about 30,000 degrees Fahrenheit by the arc. The aperture gas then converts to plasma and is discharged via a tiny opening at the end of the welding flame.

As with GMAW, a shielding gas surrounds the weld pool to produce an inert environment that keeps the weld pool clean and free of oxygen, which rusts the metal.

3. What is plasma arc welding process?

Plasma arc welding is an arc welding methodology in which heat from a constricted arc established between a tungsten/alloy tungsten electrode and the water-cooled nozzle or between a tungsten/alloy tungsten electrode and the work is used to generate coalescence.

4. What are the problems associated with Plasma Arc Welding?

Arc reignition is problematic when the electrode-to-workpiece distance is lengthy and the plasma is constrained.

Furthermore, excessive heating of the electrode during the positive half-cycle generates tip balling, which can disrupt arc stability.

5. What are the advantages of plasma welding?

The advantages of plasma arc welding are:

– The ability to use shielding gases.

– Excellent control of arc length and intensity, resulting in reduced overheating and weld imperfections.

– A single-pass without the need for an “adjusting” zone.

– Little heat-affected zone is created due to the lack of filler metal.

6. What are the disadvantages of plasma arc welding?

The disadvantages are:

– The high cost of equipment and consumables such as electrodes, gases, torches, sensing equipment and associated maintenance costs.

7. What is the equipment used in plasma arc welding?

Plasma arc welder is an electric-arc welding machine that uses a tungsten electrode to produce heat.

The electric current flows from the power source to the tungsten electrode which is connected to the torch.

8. How is plasma arc welding done?

The plasma arc welding procedure, like GTAW (Tig), uses this plasma to transport an electric arc to a work piece.

The tremendous heat of the arc melts and fuses the metal to be welded. A Tungsten electrode is housed within a copper nozzle with a tiny aperture at the tip of the plasma welding torch.

9. What is the difference between plasma arc welding and plasma cutting?

In comparison to plasma arc welding, plasma arc cutting uses a higher velocity.

In plasma arc welding, the plasma is driven through a fine-bore copper nozzle, which squeezes the arc and causes the plasma to exit the orifice at high speeds and temperatures nearing 20,000 °C.

10. What is plasma arc welding used for?

Plasma welding is suited for fillet welds and can eliminate spatter due to its highly directional arc.

Because of its minimal electrode consumption, it can provide high-quality welding for an extended period of time.

Although the welding machines are more expensive than TIG welding machines, the operating costs are modest.

11. What are some dangers of plasma cutting?

Working with a plasma cutter, like most tools on a job site, has its share of potential hazards. When operating with a plasma cutter, three of the most dangerous threats are noise, air quality, and electricity.

12. Can a plasma cutter damage your eyes?

Plasma cutting arcs can also be highly powerful because the arc current ranges between 100 and 800 Amperes.

Needless to say, staring at such a bright arc can easily cause eye damage, potentially irreversible damage that leads to blindness.

13. What are the problems associated with arc welding?

When properly installed and handled, an arc welder is very safe; nevertheless, if used incorrectly, the operator can be exposed to a variety of risks such as toxic gases, dusts, burns, fires, explosions, electric shock, radiation, noise, and heat stress.

Any of these dangers has the potential to inflict injury or death.

14. How hot is plasma arc?

The arc created between the electrode and the workpiece is restricted by a fine bore, copper nozzle. The temperature and velocity of the plasma emitted from the nozzle rise as a result.

The temperature of the plasma exceeds 20 000°C, and its velocity can approach that of sound.

15. What are the safety precautions in plasma arc machining?

The furnace is designed to catch any molten droplets, so it’s not necessary to wear face protection.

It’s okay to wear a welding helmet when cutting, since it will shade your eyes from the bright arc.

When grinding, though, you should wear goggles because of the flying sparks.

Other precautions include;

  • Allowing unauthorised personnel to use plasma cutting equipment without supervision or authorisation is strictly prohibited.
  • Keep a safe distance between your work and the cutting area, especially if the things in your workspace are combustible.
  • Always keep a fire extinguisher nearby.

16. What types of metals are plasma cut?

The cutting process can be used on almost any metal, including coatings, plastics, and dissolved metals.

17. How does plasma welding is done?

Plasma welding is carried out by placing the tungsten torch tip into the hole in the end of the copper nozzle and allowing a current of electricity to flow through it from the power supply.

It takes a high voltage circuit to produce an arc between the torch and workpiece.

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