Gaggenau, Germany - Three years ago Precitec KG (www.precitec.com) introduced a high-power, 6kW solid-state laser welding head. To prove endurance the company needed to use the power from two lamp-pumped rod type lasers delivered through twin fiber into the welding head.
Today the company has proven the optimized design of this welding head by using it with a 10kW fiber laser from IPG (www.ipgphotonics.com). This high-power capability is a result of the optical design that uses high-purity quartz substrates and built-in water-cooling circuits to eliminate the small percentage of absorbed laser power (less than five percent).
Laser weld, single pass, butt joint pipeline steel X70, 12mm thickness (edge preparation laser cut). Laser power 10.2 kW, welding speed 2.2 m/min.
The fiber laser, which was first tested at BIAS Bremen (www.biass.de), starts welding with a loud bang if the laser is started above the specimen without a power ramp. The first tests with 200mm focal length easily destroyed a cover glass slide because of the start explosion without power ramping and a very large plasma plume beneath the Cross Jet. In tests at SLV-Rostock (www.slv-rostock.de) a 250mm focal length produced higher lifetime of the optical components.
GMA-laser-hybrid weld, single pass, butt joint. Material: AW 6008, thickness 8 mm (extruded profiles) PL = 10.5 kW, vS = 8 m/min
Currently the optical setup is a collimator with 125mm and a focusing lens with 250mm focal length. Using the 200-micron core diameter IPG fiber produces a spot of approximately 400-micron diameter, which is sufficient for high-power welding.
Tests were performed with steel and aluminum alloys as autogenously or gas metal arc assisted welds. For autogenous welding the speed is between 2m/min for 12mm thickness and 15m/min welding speed at 4mm thickness. Aluminum shows a slightly higher welding speed at the same penetration as steel material. In aluminum welding there is a blue plasma plume between the work piece and nozzle.
The next challenge is a 15kW welding head, which was to be supplied in February 2005. - DAB