New horizons in laser welding

Three years ago Precitec KG (www.precitec.com) introduced a high-power, 6kW solid-state laser welding head.

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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).

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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.
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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.

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GMA-laser-hybrid weld, single pass, butt joint. Material: AW 6008, thickness 8 mm (extruded profiles) PL = 10.5 kW, vS = 8 m/min
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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

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