An advanced modelling approach for micro EDM wear analysis

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Capabilities for micro and nano processing on a wider range of materials, including the structuring of true 3D-forms, are becoming increasingly important for the development of innovative new applications in order to enable flexible and cost-efficient manufacturing of multifunctional products made of different materials in many high value manufacturing sectors, including biotechnology (e.g. biosensors, micro fluidics) and optoelectronics. The micro scale Electro-Discharge Machining process (micro EDM) brings unique structuring capabilities that can be crucial for the development of cost effective processing chains for the production of micro and nano products. One major attraction of micro EDM is its ability to machine almost any deep 3D structure on any conductive material, regardless of material hardness and wear resistance, making it, for instance, particularly useful for producing high performance micro injection tool inserts. However, like most micro machining technologies, micro EDM still suffers from a relative lack of maturity and intensive R&D work is still required to fully realise its potential and to enhance micro manufacturing capabilities as a whole, which is the ultimate purpose of this proposal. More specifically, analytical models representing accurately the physical behaviour of EDM at the micro scale remain to be developed, preventing accurate pre-machining prediction. In particular, during a die sinking micro EDM process, the micro features present on the electrodes used to machine a work-piece will undergo severe wear, resulting in difficult to predict electrode shape deformations.One idea put forward in this proposal is that die sinking micro EDM could become a highly cost effective manufacturing process for the production of complex micro 3D shapes, providing that one could model accurately the wear effect on electrode shape deformation. Deformation could thus be compensated for at the design stage by adding carefully placed extra volume to the electrodes. The main issue with the wear modelling and simulation approaches developed so far is that strong assumptions on difficult to predict parameters (flushing, material properties variations at the micro scale, crater shapes etc) have had to be made, due partly to technological limitations in areas such as metrology and experimental setup. This proposal will build on combined recent advances in metrology, material science and micro manufacturing in order to develop an advanced experimental set up, allowing a more predictable, stable and measurable environment for die sinking micro EDM and to consequently validate a new, more accurate modelling and simulation approach for micro EDM wear. A special focus will be on the machining of amorphous and ultrafine grained metals.