FEATURE: SHIPBUILDING
“Being able to produce a high- quality, relatively fast weld on one side is a very big advantage”
A particularly important use-case for
laser welding in shipbuilding, stressed Shekel, is in the joining of dissimilar metals together, for example in panel building. ‘You should not need a separate filler material or component,’ he said, ‘because with deep penetration laser welding, the coupling can go directly from one part to another. Another important part of the laser is the low heat-affected zone. A high quality of metal is required for shipbuilding, and you want to keep that quality with the weld. With a low heat-affected zone there is less residual stress on the weld.’
The power of diode lasers Johannes Schäfer, technology and strategic key account manager at diode laser manufacturer Laserline, sees shipbuilding as a relatively conservative market, but one gradually taking on new technologies. ‘We see that there are still a lot of processes which have been used in the past, such as submerged arc welding – a laborious process that can involve workpiece distortion – but there is also laser
technology now being used for cutting and for welding.’ Schäfer has noted a particular shift in the shipbuilding industry towards laser-gas metal arc hybrid welding, a combination of gas metal arc (GMA) welding and laser beam welding. ‘Despite the higher welding speed that laser GMA welding offers, there is less distortion in comparison to the old fashioned processes, which can help reduce production costs,’ he said. ‘It’s not going to be used for short seams or traditional GMA mouldings, but it can be useful for long seams, section weldings around different thicknesses, so around 5mm up to 15mm and special joints.’ He explained that diode lasers are
different to other laser systems for shipbuilding, in that the combination of high power output and comfortable spot sizes can allow for optimal gap bridgeability. In addition, the energetic homogeneity of the spot and the high absorption capacity of a typical wavelength mix generate unusually calm melt pools, leaving almost no impurities on the areas adjoining the seams. As combined diode laser systems can reach powers of up to 60kW today, even ships’ sides of 50mm thickness can be welded with two welding runs (layer and opposite side). ‘That has an influence and impact on the properties like hardness,’ said Schäfer. ‘Typically, the hardness peaks in the heat-affected zone, that’s a normal point of welding. And we can decrease those
WWW.LASERSYSTEMSEUROPE.COM | @LASERSYSTEMSMAG
hardness peaks for the types of steels used in shipbuilding industries.’ In terms of wavelengths, Schäfer
explained that Laserline generally produces infrared lasers for welding in shipbuilding. ‘We produce diode lasers up to a very high power, up to 45kW or even more, but of course, for the shipbuilding industry we have the special 60kW laser. It depends on the volume and thickness of the sheets that the customer demands.’
Developing lasers for the maritime sector The 60kW power for lasers in shipbuilding is the focus of a research project in which Laserline has been involved for several years. Based in Germany, Thick Metal Sheet Welding by High-Power Diode Lasers for Maritime Applications (DIOMAR), involves a consortium of experts working to develop new diode laser beam sources with a maximum output of up to 60kW in continuous-wave mode.
This is with the aim of ensuring high-
quality laser welding processes for steel sheet thicknesses of up to 30mm are available for use in shipbuilding and other maritime applications. Laserline has been responsible for the
development of the new high-power laser diode sources. Other organisations in the group include German research institute Laser Zentrum Hannover, shipbuilding firm Meyer Werft, and electronics manufacturer Held Systems. DIOMAR is funded by the
g AUTUMN 2021 LASER SYSTEMS EUROPE 15
Nightman 1965/
Shutterstock.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46
