Reflectometry-based investigation of temperature fields during dual-beam Laser Metal Deposition

Laser Metal Deposition (LMD) is a high deposition rate metal Additive Manufacturing process. Its applications are basically repair, cladding and manufacturing. The two most commonly used LMD processes are powder-based (LMD-p) and wire-based (LMD-w). Despite the fact that wire-based LMD is more material efficient, process stability is a major concern. By adding a modulated laser beam to the continuous process beam, a change of the melt pool geometry and increased energy absorption are observed. This relation shows great potential to increase process stability. In this contribution, the positive effect of the dual laser-beam use on LMD-w processes is demonstrated. To understand the cause-effect relation, the workpiece temperature field was investigated by optical backscatter reflectometry ( OBR). The results were then correlated to simultaneously performed IR camera measurements of the workpieces upper surface. By better understanding the thermal phenomena in dual-beam LMD, research can improve process temperature control. This leads to a new perspective for the LMD-w manufacturing process in many industry sectors such as mobility, energy and engineering.