Plasma Arc Welding
Plasma arc welding is the same as TIG welding and it is formed between the workpiece and a pointed tungsten. However, placing the electrode in the body of the torch allows welders to separate the plasma from the envelope of the shielding gas. From there, the plasma is forced via a fine-bore copper nozzle that constricts the arc. The process can produce three operating modes by a varying plasma gas flow rate and bore diameter.
It is one of the most popular welding solutions in the United States. Aluminum Welding Specializes in offering plasma arc welding in Los Angeles, Riverside, Ventura, San Bernardino, and Orange County. It is good to go for professionals who know the work well when looking for plasma arc welding in the United States.
Source of Power
The plasma arc welding is usually operated with Direct current (DC), drooping power source characteristic. It derives its unique operating features from a separate plasma and special torch arrangement. It is possible to add a plasma control console on a conventional TIG power source.
The market also has purpose-built plasma systems. The plasma arc isn’t readily stabilized with the sine wave AC. Reignition of the arc is hard when the plasma is constricted and when there exists a long electrode to workpiece distance. Furthermore, excess electrode heating during the positive half-cycle results to balling of the tip and this can disturb the stability of the arc.
The other available power source is the special-purpose switched DC. It imbalances the wave form to decrease the period of the electrode positive polarity. This keeps the electrode sufficiently cool to achieve arc stability by maintaining a pointed tip.
Even though the arc is usually initiated using the HF, it is formed for the first time between the plasma nozzle and the electrode. The ‘pilot’ arc is held in the torch body until it is required for welding and then it is transferred to the welding workpieces.
The pilot arc system makes sure there is a reliable arc standing. The pilot arc is usually maintained between the welds and obviates the requirement for HF that can lead to electrical interference. Aluminum Welding experts are perfect at executing this exercise.
The electrode that is utilized for the plasma process is typically tungsten – 2 percent thoria and it is a copper plasma nozzle. The tip diameter of the electrode is not as crucial as for the TIG process and the welder should maintain it at approximately 30 to 60 degrees. The diameter of the plasma nozzle bore is so crucial and a very small-bore diameter for the gas flow rate and current level will result to melting and even excessive nozzle erosion.
It is important to use the largest bore diameter for the operational level of current. However, a bore diameter that is too large can result into problems in maintaining a keyhole and with the arc stability. As a welding company, we know how to handle the electrode in the best way possible. It is good to go for a reputable brand when looking for someone to work on your plasma arc welding project.
Plasma and the Shielding Gases
The main gas combination is argon for plasma gas with the argon plus 2 to 5 percent hydrogen as the shielding gas. You can use Helium for Plasma gas but due to the fact that it is hotter, it reduces the nozzle’s current rating. Helium has a lower mass that can make the keyhole mode harder. Experts know how to apply this feature in the best way possible.
The Applications of Plasma Arc Welding
1. Micro-Plasma Welding
Traditionally, micro-plasma welding was used to weld thin sheets that are down to 0.1mm thick and mesh and wire sections. It has a needle-like sniff arc that minimizes arc distortion and wander. Even though the corresponding TIG arc is more diffuse, the modern transistorized (TIG) source of power may produce a highly stable arc at lower levels of current. It is one of the most common applications of micro-plasma welding.
2. Medium Current Welding
Medium current welding is a great alternative to TIG when you use it in the melt mode. The first benefit is higher tolerance to surface contamination including the coatings because the electrode is in the body of the torch. The other benefit is a deeper penetration from the high plasma gas flow.
The main disadvantage is with regard to the bulky nature of the torch and this makes manual welding to be very hard. In the mechanized welding process, you must pay greater attention to maintaining the torch to guarantee you consistent performance.
3. Keyhole Welding
Keyhole welding has so many benefits that you can exploit including high welding speeds and deep penetration. When you compare this with TIG arc welding, it can penetrate plates that have a thickness of up to 10mm. However, when you use a single pass technique to weld, it is more ideal to limit the thickness to 6mm.
The normal method is using the keyhole mode with a filler to ensure there is a smooth weld bead profile without an undercut. For thicknesses that are up to 15mm, you use a vee joint preparation that has a root face of 6mm. Welders employ a two-pass technique in this case. The initial pass is autogenous and the second one is made in the melt mode with an addition of a filler wire.
Like the welding parameters, you must carefully balance the filler wire addition in the keyhole and plasma gas flow rate to maintain the weld pool stability and keyhole. The technique is only ideal in the process of mechanized welding. Even though you can use it for positional welding, normally with this current pulsing, it is usually applied in the high-speed welding of a thick sheet material that is more than 3mm in a flat position. In pipe welding, you must carefully control the plasma gas flow and slope-out of current to close the keyhole with no leaving of a hole.
Plasma arc welding is among the welding services that are on high demand in the United States. If you want to get the best services, all you need to do is come to Aluminum Welding. The company has a highly specialized team of professionals who will help you with all forms of metal fabrication services. You can be sure of getting the best results at the most affordable rates when you come to Aluminum Welding.
From our offices in California, Aluminum Welding serves households and businesses in Ventura, Riverside, San Bernardino, Los Angeles and Orange County. We offer a broad range of metal fabrication services to our esteemed customers. Contact us today to learn the kind of services that you can get from us.