SGER: High Pressure Dynamic Piercing of Microholes

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Micro-holes, holes of 200-300 um diameter, have applications in MEMS, pneumatic sensors and manipulators, fluidic filters, fuel injection nozzles, bio-medical filters, ink jet printer nozzles, optical apertures, high pressure orifices, standard defects for testing materials, micropipettes, guides for wire-bonders and spinning nozzles. Various micromachining methods such as microdrilling and micro-EDM can produce these holes with a high degree of accuracy. However, their production rates are often insufficient for production line use. The objective of this SGER research is to create microholes by means of a high-pressure liquid pulse instead of solid punches. The research strategy is to suppress the natural ductility of the sheet material by hydrodynamic pressure and create shear localization at the die corners to initiate a straight and burr free hole. It is proposed to start with copper sheets followed by aluminum and stainless. There are many scientific and technological challenges in this approach including the design and assembly of tooling with precision in the mesoscale, sealing of the tooling for dynamic high pressure pulse, dynamic behavior of the sheet material at a scale where the grain size and micro-hetrogeniety effects cannot be ignored, and micro-tribological issues such as friction at the sheet /blank holder interface. Knowledge and understanding generated in this research will benefit micro and meso manufacturing research and teaching in general, and microforming in particular.