Line of modular processing heads for laser metal deposition with powder and wire

Laser cladding processes have long played a key role in the aerospace industry. This is because laser-based additive manufacturing offers the possibility of realizing complex component geometries, increasing product quality and setting oneself apart from competitors. High-performance processes, beam tools and machining heads that metallurgically combine different materials or generate structures are in demand. They can be used to functionalize surfaces, subsequently modify component designs or repair long-life assemblies instead of replacing them completely.

The “COAX“ system family provides the appropriate tools. It comprises a complete line of modular processing heads for laser buildup welding with powder and wire. For this purpose, the Fraunhofer IWS develops special coating heads that feed the material coaxially to the laser beam at the processing location and enable a direction-independent welding result. These systems are used in common laser systems and hybrid processing centers for additive manufacturing. Specially developed coating units are optimized for use in extreme conditions or confined spaces, while others are suitable for particularly fine structures or for high-quality materials such as titanium or high-entropy alloys.

Energy and resource efficiency are gaining ever more significance, which is why the Fraunhofer Institute for Material and Beam Technology IWS has worked with its partners to develop an alternative for conventional steel construction that not only constitutes a process technology solution, but also forms the basis for hardware and laser safety. This solution facilitates gentler machining of high-strength materials, as well as significantly reducing energy consumption and costs while greatly increasing process speed. The energy input required for the component can be reduced by up to 80 percent compared with conventional joining processes. Not only that, subsequent straightening of the component is eliminated entirely from the process.

Many technical structures feature some form of steel construction. Be it a container ship, railway vehicle, bridge or wind turbine tower, any one of these structures can have several hundred meters of welding seams. Conventional industrial processes such as metal active gas welding or submerged arc welding are usually used for this purpose. Here’s the problem: Due to the low intensity of the arc, a large proportion of the energy expended is not actually used in the welding process, but is lost to the component in the form of heat. The energy required for post-weld treatment is often of a similar magnitude to that required for the welding process itself. “These energy-intensive processes cause significant thermal damage to the material and result in severe distortion of the structure, which then demands very costly straightening work afterwards,” emphasizes Dr. Dirk Dittrich, who heads up the Laser Beam Welding group at Fraunhofer IWS.