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Welding aluminium materials using high power diode lasers

Objective



Aluminium materials are used predominantly in container and window manufacture, as packaging material and in transport vehicles. However, the level of market acceptance of a material, is determined not only by the specific characteristics of that material but also by the availability of reliable and economically efficient machining techniques such as cutting, machining and joining. The deployment of conventional joining processes has previously been thwarted by the temperature dependent characteristics of the material. The occurrence of welding seam faults depends largely on the additional materials used, temperature distribution at the welding points and on the performance profile of the energy used. The use of lasers presents an alternative to conventional welding processes.

However, conventional Nd:YAG solid state and CO2 lasers must be operated using the intricate two beam technique in order to eliminate the occurrence of pores and tension cracks (expansion of the welding point using two laser beams). The characteristic rectangular profile of the high power diode laser presents an economically efficient alternative to this method. This high power diode laser permits aluminium materials to be welded faultlessly, with virtually homogeneous intensity distribution. The high power diode laser differs from conventional lasers not only in the beam profile, but is also very much more efficient and has better absorption characteristics as well as lower manufacturing and operating cost. By virtue of its extra ordinary compactness and high flexibility, the high power diode laser can be integrated with ease in existing production lines. Current advances in optics, semi conductor and laser technology are resulting in new and different generations of highly innovative beam sources with considerably enhanced beam quality and higher power levels at the surface of the workpiece.

This will soon permit high power diode lasers to be used for the first time to weld metallic materials effectively. Due to the rectangular profile, the temperature field on the workpiece and in the dynamics of the meld will remain constant, which does not happen when conventional techniques and lasers are used. This represents a considerable advance in welding technology for aluminium alloys. The aim in the project envisaged, is, therefore to develop the high power diode laser to a point at which it is entirely suitable for welding aluminium materials. In addition to optimising the laser, this will entail in particular accelerating the progress of the welding technology and its integration in the production line. The aims can be described in detail as follows: development of the high power diode laser with power densities in excess of 1 106 W/cm Technology development in order to achieve welding speeds above 5 m/min Maximum welding seam thickness of 3 mm 100 % non porous, welding seam with no heat cracks Design and construction of a handling and sensor system The extent to which the process is influenced by additional wire and its position in relation to the focal spot And the influence exerted by the working gas will be investigated in order to ensure a reliable welding process as the outcome.

The project consortium, consisting of 4 SMEs from 3 European countries, presents an opportunity to develop a diode laser, the integration of the laser within a handling system and investigation of the manufacturing applications The project partners thus fulfil the requirements which will enable them to develop a welding process and system which, with the integration of a high power diode laser in existing production lines, will be able to weld aluminium together in an efficient, economical process. The research project proposed here complies with the funding guidelines of the EC and focuses on Item 1.1.1.S as well as 1.1.4.S.

Funding Scheme

CRS - Cooperative research contracts

Coordinator

Laserline Gesellschaft für Entwicklung und Vertrieb von Diodenlasern GmbH
Address
Maria Trost
56070 Koblenz
Germany

Participants (4)

FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V.
Germany
Address
Steinbachstrasse 17
52074 Aachen
Goma B.V.
Netherlands
Address
Ruurloseweg
7255 MA Hengelo
LASERPLUS OY
Finland
Address
16,Konepajankatu 16
11710 Riihimaeki
Valk Welding b.v.
Netherlands
Address
Staalindustrieweg
2950 AB Alblasserdam