Closed-loop laser volume ablation with adaptive scan paths

Abstract

This research focuses on closed-loop control in laser volume ablation, also known as laser milling. Such process control enables precise ablation results on workpieces with much wider tolerances regarding the initial surface geometry, internal structure, or its response to the incident laser beam, compared to conventional open-loop processing. However, state of the art closed-loop ablation systems incorporate the process control at the cost of increased processing time. The two main causes are the alternating between processing and measuring, and the use of static scan paths that do not adapt continuously to the evolving geometry of the workpiece during processing. This study addresses this issue by proposing a parallelized work flow of processing, measuring the surface topography and adaptive path planning, eliminating interruptions and achieving faster processing through continuously optimized scan paths. The realized machining system achieved a mean reduction in processing time of 29%, 36%, and 52% on three different test geometries compared to the state of the art.