The Basics of Plasma ARC Welding (PAW)
One of the key elements of this type of weld is that it can be applied to just about any type of metal that needs to be connected. Welders have quickly discovered that they can use this welding process in a variety of situations and even when materials of differing types of metal need to be bound.
What Is Plasma Arc Welding?
The PAW weld is one that is remarkably similar to GTAW welding (gas tungsten arc welding). In this process, the arc is formed between the metal and the electrode. What separates PAW welding from GTAW is that PAW welding allows the welder to be able to place the electrode in the body of the torch. This separates the weld from the protecting gas.
The plasma is then fed through a nozzle which then compresses the arc. This forces the plasma away at a very high speed, which creates a high temperature weld. This method uses a non-consumable tungsten electrode. The arc can be formed so that it strengthens the plasma transferring through the nozzle. There are two types of PAW welding processes.
In the transferred PAW method, direct polarity DC current is used. The tungsten electrode is aligned so that the “-ve” terminal and of the metal can be applied directly to the “+ve” terminal. This process, the arc and plasma are both moved toward the work area. This greatly enhances the amount of heat that is produced. This allows solid sheets to be easily joined together.
In the non-transferred PAW method directed polarity DC current is also used. It is remarkably similar in that the tungsten electrode can be aligned to the “-ve” on the nozzle so that they can be connected to the “+ve” pole. What differs is that the Arctic generates in the nozzle, which enhances the ionization of the gas within the torch. The torch is then able to transfer the ionized gas which makes it ideal for joining thin sheets of metal.
How the Plasma is Created?
One of the most important elements of this type of welding process is the plasma that is created. This helps to generate the high temperatures that are needed to create the weld.
The truth is that an amazingly simple physics principle is used to help facilitate this. By constricting the electric arc that is passing through the orifice of the nozzle, plasma is created. This hot ionized gas is then forced through the opening. The tighter constrictions produce a higher temperature arc, which can then be directed toward the work area. This will quickly melt almost any metal because of the temperatures generated. Often, that can exceed 9000°F.
The Advantages and Disadvantages
Because of the wide range of uses, clearly PAW has some major advantages. The array of applications makes this an especially useful type of welding process in many areas and industries. However, it is the high degree of expertise that is needed for success that deters many from using it.
Because of the greater sophistication and technology advancements in our society, it would not be surprising to see this become one of the most preferred options for welding materials. • The amount of power that is needed is quite low.
- The speed at which a weld can be constructed is quick, which makes it easy to join thick and hard work pieces together quickly.
- The welding device functions at an extremely low amperage.
- The penetration rate is high as is the arc.
- A very steady arc can be produced through prolonged use.
It has a wide array of applications, so all it needs is more skilled workers to be able to accomplish the tasks needed though it has some disadvantages.
- This is a very noisy welding process.
- While the cost of producing the weld is low, the equipment needed is quite expensive.
- There is a higher amount of radiation that is released.
- Requires a very well trained and highly skilled welder to be able to perform this type of weld.
Where Is PAW Welding Used?
Because of the temperatures that this type of weld can produce, its application is often based in heavy types of manufacturing where large sheets of metal need to be connected to one another. Major Applications of PAW Welding are:
- The Joining of Stainless-Steel Tubes and Pipes.
As mentioned, because of the heat generated, the number of applications where this type of welding can be useful is quite expansive. However, what many people do not realize is that even intricate work can be performed using this kind of welding technique.
- Often used in electronics industries.
In the electronics industries where the work that is done is conducted in exceedingly small areas, there are still many applications where PAW welding is perfect. This mainly occurs where small, thin layers of metal need to be welded together to allow for conduction of electricity or in protecting of the circuit board and other inner workings.
- Used in Manufacturing of Turbine Blades.
Small stainless-steel tubes and pipes, even large ones can be connected using this welding technique. It is also ideal in helping to properly coat and connect turbine blades.
- Aerospace and Marine construction and manufacturing.
One area where you will see a great deal of use as in the aerospace and Marine technology sectors. Because of the significant amount of force applied by water and the thrust of launching vehicles into the air, the large, thick metal plates need to be securely fastened to protect astronauts and scientists from being injured or the vehicle from being destroyed.
- Used to fix tools, molds, and dies.
PAW welding can secure these metals together and provide the kind of durable weld that holds the metal pieces securely in place. It is also ideal in these industries where thousands of small electronic circuits are interconnected throughout the crafts and structures.