Quality optimisation for laser machining under transient conditions

Abstract

Quality improvements in laser machining have been achieved by a newly developed model-based optimisation strategy. The specific aims of such efforts are to assure machining quality right up to boundaries or pre-machined sections, which are inherent in intricate part geometry. Such boundaries frustrate heat-transfer and result in bulk heating of the workpiece. This in turn leads to a degradation of the machining quality. In order to achieve such optimisation, transient heat-transfer is modeled. Close inspection of the laser–workpiece interaction zone reveals that the machining front exhibits dynamic behaviour, and such mobility plays a significant role in temperature determination. Non-linear parameter adaption profiles are generated via the optimisation strategy in order to stabilise the machining front temperatures. Currently, trial-and-error based experimentation is needed in order to improve machining quality in such regions. Thus model-based optimisation has the added benefit of reducing this step whilst leading to an optimal solution. Experimental results are presented and it is demonstrated that such process manipulation can lead to significant quality improvements.