FOCUS ON LASER WELDING
The laser beam is positioned at the joint between the two sheet edges to be welded , and a filler metal is inserted in front of it at the same time . The process results in a high-quality welded seam . © Fraunhofer IWS . laser multi-pass narrow-gap welding ” project .
Laser multi-pass narrow-gap welding ( Laser MPNG ) uses a commercially available high-power laser and differs from conventional methods because of its reduced number of layers and drastically reduced seam volume . These elements of the welding process are its key benefits .
“ Depending upon the component , we can reduce the energy input for the component during welding by up to 80 per cent , and we can lower filler material consumption by up to 85 per cent compared to conventional arc processes ,” reported Dr . Dittrich .
“ It was not necessary to carry out a straightening process on the component studied . As a result , we can cut production time and costs , process high-strength steel materials and significantly improve the CO₂ balance of the entire production chain . Given the significant number of steel structures being built in Germany and around the world , this could prove to be hugely advantageous ,” he added .
This is because the high intensity of the laser beam guarantees that the energy input is highly localised at the welding point , whereas the surrounding areas of the component remain comparatively cold .
“ The welding time is also reduced by 50- to 70 per cent ,” said Dittrich , citing another advantage .
The new process also offers improved weld seam quality : the seams are significantly
Shipyard general welding welding operations .
slimmer and the edges are virtually parallel , whereas in conventional welding processes the seams are V-shaped .
“ If laser welding were used in steel construction processes , it would become a unique selling point for medium-sized businesses in Germany and strengthen its market position in the face of international competition ,” stated Dittrich with confidence . “ We are providing the industry with an efficient form of joining technology that is set to revolutionise steel construction on account of its cost-effective application and resourcesaving production process .”
Steel girders for indoor crane construction
The researchers from Fraunhofer IWS demonstrated the performance of their new development using a practical example from indoor crane construction . They deployed the new welding technology using special system technology and an integrated beam protection concept .
The design of the experimentally built , 4m-long rectangular profile of an indoor crane segment conformed to the design and manufacturing guidelines of comparable , conventionally produced components . Weld seams typical of the application were produced : a butt joint on 30mm plates and a fully joined T-joint ( 15mm plate ).
“ For a 1m weld seam , it was possible to reduce the costs for a sheet thickness of 30mm by 50 per cent compared to submerged arc welding , including the subsequent straightening process . For sheet thicknesses of less than 20mm , where metal active gas welding processes are also commonly used ,
we can cut production time and costs , process high-strength steel materials and significantly improve the CO 2 balance of the entire production chain
ISMR April 2022 | sheetmetalplus . com | 33