Laser beam welding of aluminum alloys with diode pumped Nd:YAG lasers

Abstract

A new generation of high power solid state lasers for industrial laser applications is available on the market. Diode pumped Nd:YAG lasers with high beam quality and output power of more than 4 kW have technological and economical advantages compared to lamp pumped sources. One advantage of higher beam quality is the use of longer focal lengths enabling the protection of the working head or the use of scanning optics.For laser welding of aluminum alloys, the advantages and disadvantages of the high beam quality on the process stability were examined using a 4.4 kW diode pumped laser with a fibre core diameter of 400 μm.On one side the high beam quality leads to higher power density and therefore deeper penetration and on the other side to more unstable processes. By using different focal lengths and twin spot optics with variable distance and power distribution between the spots, the influence of the keyhole size and shape on the weld seam surface and geometry was investigated. The enlargement of the keyhole in the welding direction and the separation of the beam into two single spots resulted in a significant stabilisation of the process and a reduction of the porosity and blow-hole formation frequency.A new generation of high power solid state lasers for industrial laser applications is available on the market. Diode pumped Nd:YAG lasers with high beam quality and output power of more than 4 kW have technological and economical advantages compared to lamp pumped sources. One advantage of higher beam quality is the use of longer focal lengths enabling the protection of the working head or the use of scanning optics.For laser welding of aluminum alloys, the advantages and disadvantages of the high beam quality on the process stability were examined using a 4.4 kW diode pumped laser with a fibre core diameter of 400 μm.On one side the high beam quality leads to higher power density and therefore deeper penetration and on the other side to more unstable processes. By using different focal lengths and twin spot optics with variable distance and power distribution between the spots, the influence of the keyhole size and shape on the weld seam surface and geometry was investigated. The enlargement of the keyh...