Laser micro-machining of freeform surfaces: Accuracy, repeatability and reproducibility achievable with multi-axis processing strategies

The requirements that complex 3D miniaturised components have to satisfy are constantly increasing for various application areas, e.g. in aerospace, biomedical and electronics, and hence there is a sustained drive to broaden the capabilities of precision manufacturing processes. In this regard, state-of-the-art Laser Micro-Machining (LMM) systems have been attracting significant industrial interest with their emerging capabilities for multi-axis machining. However, intrinsic limitations of component technologies of such systems can impact the machining accuracy, repeatability, and reproducibility (ARR), especially in complex processing strategies requiring the simultaneous use of multiple axes, and consequently to affect the overall processing uncertainty. Herein, the aim of this research is to propose a systematic method for assessing the overall performance of such LMM systems when they are deployed for laser structuring/patterning/texturing of freeform surfaces. In particular, the method employs a series of laser processing tests on spherical samples to quantify the contributions of different error sources on the machining ARR when implementing simultaneous multi-axis processing strategies under quasi-static and dynamic conditions. An experimental validation of the proposed method is conducted on a representative state-of-the-art LMM system and then conclusions are drawn about its capabilities to determine the processing ARR of multi-axis LMM systems. This research provides an insight into the limitations and manufacturing challenges in deploying such systems for the fabrication of complex 3D components.