TWI Frequently asked questions
Updated by Chris Allen
It has been known for many years that the combination of a laser beam and an electric arc can produce welds with many of the technical characteristics of those made using just a laser, i.e. deep penetration and low distortion.
However, hybrid or arc augmented laser processes - whereby both the laser and arc impinge on the same molten pool - give higher processing speeds, with even deeper penetration and greater tolerance to fit-up, than can be achieved by the laser alone. Thus, the technical benefits of laser welding are retained, or enhanced, whilst the economy of the process is improved.
Plasma augmented laser (or hybrid plasma/laser) welding is one variant of laser-arc hybrid processing which possesses a number of advantages over laser welding alone. A common configuration of the process, shown in Fig.1,uses a co-axial welding head to deliver the laser through the plasma to the workpiece. Using this design of welding head, the process is co-axial and could be used to process in two or three dimensions.
Fig.1. Plasma augmented laser head
(Courtesy of PLT) The main advantages of plasma augmented welding can include:
- faster processing speeds and/or deeper penetration compared with either laser or plasma alone
- greater tolerance to variation in joint fit-up compared with laser alone, resulting in reduced requirements for edge preparation accuracy
- lower capital cost - reduction of 30-40% compared with laser alone, due to reduction in laser power requirement
- higher electrical efficiency, up to 50% reduction in power consumption
- co-axial heads give 3-D processing capability
