A Tool-Based Precision Hybrid Laser-Electrochemical Micromachining Process: Process Analysis by Multidisciplinary Simulations and Experiments

Abstract

Hybrid laser-electrochemical micromachining is a fast and force-free processing technique to machine difficult-to-cut multi-materials with conductivity variations and has the advantage of accelerated material dissolution, oxide layer weakening and surface quality. In this process, the laser can assist electrochemical dissolution or participate in material removal depending on the fluence available on the workpiece surface. The tool-based configuration allows delivery of laser and ECM at higher machining depths and achieves homogeneous application of the two aforementioned processes. The combination of laser and ECM results in high material removal, better surface integrity and processing of advanced materials. On passivating materials, the oxide formation is weakened. In this research, a multidisciplinary model scheme is proposed using a global modelling approach where the model mimics several microscopic physical and chemical phenomena involved in this tool-based hybrid laser-ECM process. The model takes into account electric currents, fluid dynamics, modelling of laser source, hydrogen and oxygen gas generation and heat transfer in solids and fluids. The model allows to study temperature effects on each of the phenomena in the model. Material removal is simulated by using a deformed geometry feature and an automatic remeshing technique generates a new boundary for each subsequent solution step on Comsol® multiphysics platform. The multiphysics model is presented in detail with a brief description and intuitive explanation of each physics module. The proposed multidisciplinary model scheme can improve the physical understanding of the hybrid laser-ECM process as well as assist in process design for specific applications. The model allows to predict the machined profiles and current density distribution simultaneously. This model also provides insights into several multiphysics phenomena occurring in the interelectrode gap which are difficult to characterize experimentally and therefore the model can act as a virtual sensor. In the later sections of this paper, model based findings are supported experimentally.