Plasma metal inert gas shielded arc welding

The Plasma Arc Welding Process

Plasma arc welding (PAW) is an advanced form of arc welding used in many industries today. The process uses a welding torch and a welding power supply to create an electric arc between the workpiece and a tungsten electrode. This arc causes a gas, such as argon or helium, to be ionized, creating plasma, which melts the consumable electrode and the parent material.

History

The technology for plasma arc welding was first developed in the 1950s by Russian scientists. The process was originally referred to as electrical current discharging at atmospheric pressure (ECDA). In the United States, the process was later called plasma arc welding.

Process

The process of plasma arc welding is similar to that of conventional arc welding, but instead of using a shielding gas, the welding arc is contained in an inert gas shield. The inert gas is typically argon, helium, nitrogen, or a combination of these. The gas is forced through the gas delivery hose, which is encased in the welding torch. The gas is then forced through the electrode and onto the workpiece. The electrode, which is typically made of a tungsten alloy, is connected to the welding power supply, which can operate either in DC (direct current) or AC (alternating current) mode.

DC welding operates on a constant voltage, while AC welding operates at an alternating voltage. The voltage can be varied depending on the process parameters, such as the thickness of the base material and the amount of penetration required. The current is then directed through the electrode and onto the workpiece, creating an arc. This arc is usually between 50 to 150 amp in strength and has a temperature of about 16,000 °F (8,900 °C). The intense heat created by the arc melts the base material and the consumable electrode, forming a weld pool. As the welding progresses, the molten metal solidifies and forms a single weld joint.

Advantages

Plasma arc welding offers several advantages over traditional welding techniques. It produces high-quality, consistent welds at a faster rate than other processes. This is because the weld area is smaller and contains less heat-affected zone than other processes. Additionally, the high speed and precision of PAW results in a near-perfect metal deposition rate and shape. This eliminates the need for post-welding treatment and material preparation, reducing manufacturing costs.

The process is also simple to set up and can be used in a variety of applications, including high-temperature and corrosion-resistant materials. The process also offers improved penetration compared to other forms of welding and is suitable for welding thicker materials.

Disadvantages

Plasma arc welding requires special equipment, such as welding power sources, welding torches, and welding blankets, which can be expensive. Additionally, the technique requires more skill than other forms of welding and is not as forgiving of errors or imprecise settings as other methods. The process also produces a significant amount of heat and ultraviolet radiation, which can be damaging to unprotected skin. Lastly, the process is limited in its ability to weld certain materials.

Conclusion

Plasma arc welding is a reliable and cost-effective form of welding that produces high-quality welds at a fast rate. The process is suitable for a variety of materials and is easy to set up and operate. The process does require special equipment, however, and is not suitable for welding certain materials. Nonetheless, it remains an effective form of welding for applications requiring precision and tight tolerances.

GTA welding (Gas Tungsten Arc Welding) is a welding technique that uses an electric arc for welding various metallic alloys. GTA welding uses an inert gas, such as helium or argon, to shield the arc. This makes it a much more precise and efficient process than conventional arc welding.

GTA welding is often used on exotic alloys, as it can provide very precise control over the heat application, which is essential when welding materials with high melting temperatures. GTA welding is also widely used for creating precise weld beads and for welding thin sheets of metal.

The process involves creating an arc between the welding rod and the metal being worked on. An inert gas shielding the weld puddle is then added. This helps to prevent any oxidation or other contaminants from entering the arc area and interfering with the weld.

The shielding gas used in GTA welding is highly important, as it not only helps to protect the weld pool, it also helps to maintain optimal welding conditions. Different types of shielding gases are available to be used, depending on the type of weld being undertaken and the material being welded.

GTA welding is also well-suited for welding very hard metals such as stainless steel and titanium. Due to its high heat input, GTA welding can be used to weld these materials with minimal distortion of the original shape.

GTA welding is also widely used to weld aluminium and its alloys. Since aluminium is a low-melting alloy, GTA welding is particularly beneficial in achieving precisely welded joints. Additionally, GTA welding makes use of a low specific heat, which helps to prevent heat damage to the workpiece compared to other welding techniques.

In conclusion, GTA welding provides an efficient and precise method for welding a range of materials, from hard metals to aluminium alloys and beyond. The control over the heat application provided by GTA welding helps to prevent distortion of the material and makes it a particularly useful welding technique for working with exotic alloys.