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 - can give higher processing speeds, 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.
For hybrid laser-MIG/MAG (or MIG/MAG augmented laser) welding, the wire can be fed into the weld pool either behind or in front of the laser (see Fig.1). Alternatively, coaxial head designs are available which have the MIG/MAG wire feeding at 90° to the surface, and the laser beam is split either side of the contact tip and re-focused at the arc.
The main advantages claimed for hybrid laser MIG/MAG welding compared with laser alone include:
- faster processing speeds and/or deeper penetration
- greater tolerance to variation in joint fit-up, resulting in reduced requirements for edge preparation accuracy
- good weld profile through filler addition
- control of metallurgical variables, e.g. weld microstructure or cracking tendency, through filler addition
- lower per kW capital cost - reduction of 30-40% compared with laser alone, due to reduction in laser power requirement
- higher electrical efficiency per kW, up to 50% reduction in power consumption