Influencing Meltdynamics in Laser Remote Fusion Cutting

• Applicant: Professor Dr.-Ing. Michael Schmidt
• Subject Area: Joining and Separation Technology ; Production Automation and Assembly Technology
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 407703212

Laser material processing brings the advantages of contactless processing of the workpiece, high precision, and high automation. Laser beam welding, for example, is used in car body construction and increasingly in the production of components for electromobility. Research has shown that laser beam sources and optics commonly used in laser beam welding can also be used for laser beam melting cutting. This method is called Laser Remote Fusion Cutting (RFC) (or in German Frontdruckschneiden (FDS)). In RFC, the melt is accelerated by the vaporization pressure generated directly at the cutting front. This enables remote processing without the use of additional gas supply, as in conventional laser beam cutting. Changing between welding and cutting could simply be achieved by changing the parameters of laser power and feed velocity. This can save investment costs for different processing machines and save time by avoiding the need for re-clamping and readjusting between the processing steps. However, instability issues arise when changing parameters or even spontaneously. The necessary process understanding to explain or correct this behavior is lacking. The investigations in the first project phase contributed significantly to the understanding of the dynamics in the process zone. By process observations the melt movement, melt waves, and melt film thicknesses were characterized. The observations, along with simulation results, provide clues to the mechanisms involved in FDS and the occurrence of instabilities. In the requested second project phase, the interaction between evaporation and melt movement will be investigated in detail, and periodic phenomena will be examined. These could provide insights into influencing factors on melt movement, such as the exact mechanism of melt waves. This process knowledge will contribute to a better process model and stabilize RFC in critical process situations, such as cutting geometries with changes in direction.

• DFG Programme: Research Grants