Dr. Liu Kui, Singapore Institute of Manufacturing Technology, Singapore

Title

Ultra-precision Machining of Discontinuous Microstructures on Monolithic Surface 

Abstract

Discontinuous microstructures are increasingly used to enhance technical surfaces with additional functionalities, and the design of such microstructures also become more complicated and sophisticated for specific applications. In the case of optical applications, discontinuous microstructures are employed in retro-reflective arrays, micro-Fresnel lens arrays, directional micro-grating arrays, as well as electronics and microfluidics industries. As these structures are required to have ultra-fine shape accuracy, nanometre level surface roughness and strict dimensional repeatability, they are often generated on a monolithic surface by diamond machining. As the demand for optics grows rapidly, the design and application of the discontinuous microstructures also turn more complicate and sophisticated. This in-turn imposes extremely high challenges on the manufacturing.

Currently, it is impossible for conventional diamond turning to generate the large-scale discontinuous microstructures due to the loss of rotational symmetry of axis in the freeform structures, resulting low productivity, poor dimensional control, etc. Hence, manufacturers and researchers often choose to produce them by diamond cutting each individual segment and assembling all the segments together. However, this assembly process is not only tedious and time-consuming, but also requires very sophisticated human skills to achieve a tolerance of 10 micrometres or less. SIMTech is working on the existing ultra-precision machines by employing an in-situ multiple-axes freeform machining processes, to fabricate complex and discontinuous microstructures on monolithic mould. This greatly improves the form accuracy of the generated surface while eliminating any lead time lost via the multiple iterations of setup, form measurement, repair and reassembly.

Biography

Dr Liu Kui is Senior Scientist and Group Manager in Machining Technology Group at Singapore Institute of Manufacturing Technology (SIMTech). He also serves as an adjunct associate professor at the Department of Mechanical Engineering, National University of Singapore (NUS) and Co-Director of SIMTech-NUS Joint Lab on Large Format Machining. He received his BEng and MEng degrees from Nanjing University of Aeronautics and Astronautics (NUAA) in 1989 and 1996, and PhD degree from National University of Singapore in 2002. He worked as a lecture at NUAA from 1989 to 1998 and post-doctoral fellow at NUS before joining SIMTech in 2004. Dr Liu’s research interests include ductile machining of brittle materials, nano/micro machining, ultra-precision machining, exotic material machining, gun drilling, micro EDM and diamond tool fabrication. He has authored and co-authored 1 book, 6 book chapters, 170 technical papers published in prestigious international journals and conferences, filed 4 patents and 18 technical disclosures. He is an Associate Editor of Nanomanufacturing and Metrology (Springer) and International Journal of Extreme Manufacturing (IOP). He is a Board Member of Asian Society for Precision Engineering and Nanotechnology (ASPEN), Active Member of International Committee for Abrasive Technology (ICAT), Senior Member of SME, Member of euspen and JSPE.