The pilot arc is used in the plasma arc familiar with that of PAW system. Maintenance time has been increased by the relatively complicated nature of welding torch
Process Operating Procedure:
- The plasma arc is ignited using a pilot arc in a fashion similar to that of a PAW system.
- The primary arc current moves from the electrode to the workpiece and the plasma jet passes through the nozzle orifice.
- The system can be operated in this way, with the concentric cold wire being fed through the axis of the torch.
- A higher melting rate is achieved when power is applied to the wire through the contact tip and when both arcs are run simultaneously.
- The higher energy imparted to the wire by the plasma arc results in an increased wire deposition rate.
- In this operating mode, deposition rates higher than those typical of the GMAW process can be achieved.
Inspection and Weld Quality Control:
- Inspection requirements are similar to those of other arc welding or surfacing operations.
- Visual, ultrasonic, and radiographic inspection techniques are most appropriate.
- The dual action of the GMAW and plasma arcs results in weld quality that is sometimes higher than that achieved by the GMAW process alone.
- This is particularly true for aluminum alloys, because the cleaning action of the plasma arc often results in reduced porosity.
Quality control requires monitoring the plasma welding parameters for both power sources, as well as monitoring the wire feed.
In addition, the condition of the nozzle orifice (that is, the wear and concentricity of the orifice) should be monitored.
Troubleshooting:
Erosion of the copper alloy nozzle orifice will cause a change in the arc shape and will affect the weld profile. Therefore, the nozzle should be checked periodically.
Learn more about welding technique at: Hong Ky welding machine