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A novel methodology for spark gap monitoring in Micro-EDM using optical fiber Bragg grating
摘要： Micro-Electric Discharge Machining (Micro-EDM) are the most considerable micro-manufacturing process used to engineer miniaturized features on any high temperature resistive hard material. The machining parameters in Micro-EDM are very stochastic in nature. The spark gap measure acts as a vital parameter that correlates with other process parameters for enhancement of Material Removal Rate (MRR) in Micro-EDM. Real-time actual measurement of spark gap between the electrodes is highly challenging and is limited due to the small gap measure. The present work is on development of a novel sensing technique for spark gap measurement, based on a Fiber Bragg Grating (FBG) sensor. The sensing system is developed on a cantilever structure bonded with the FBG sensor, for determining accurate spark gap measure with displacement measurement of the tool electrode. The deflection on the cantilever during spark gap generation is translated into strain variations monitored by the FBG bonded over it. Experimental trials are conducted on Micro-EDM set-up with the cantilever beam based displacement sensing with a sensitivity of 10 μm/pm. Real-time spark gap data obtained by FBG are in the range of 1.1-18.6 μm and are validated against a precision measuring instrument. This sensing technology employed for Micro-EDM spark gap measurement establishes a novel technique in micromachining field and formulates a smart system.
关键词： Cantilever beam structure,Micromachining,Spark gap,Fiber optics,Micro-EDM,Bragg Gratings
更新于2025-09-12 10:27:22
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On-machine texturing of PCD micro-tools for dry micro-slot grinding of BK7 glass
摘要： While using diamond micro-tools for micro-grinding, tool re-clamping errors and low chip removal space from machining zone are the primary factors which cause large vibrations, higher grinding forces and poor surface quality. On-machine tool preparation and tool texturing prior to micro-grinding can reduce tool re-clamping error. It can further help to reduce the tool-workpiece contact area along with enhanced chip removal from the machining zone speci?cally essential during dry micro-grinding as usage of the cutting ?uid should be minimized or completely avoided for environmental aspects. In this study, end faces of polycrystalline diamond (PCD) micro-tools have been on-machine textured using micro electro-discharge machining (micro-EDM) process. Four types of textured tools are envisaged viz. tool with one micro-cavity at the center of the end face (T2), one micro-groove along the end face diameter (T3), two intersecting micro-grooves at the end face (T4) and four intersecting micro-grooves at the end face (T5). A new term “contact area ratio” is de?ned to explain the texture dimension on the end face of the micro-grinding tools. Performances of di?erent micro-textured tools (T2, T3, T4 and T5) with respect to a normal commercial tool (T1) in terms of grinding force, surface roughness and micro-slot quality are investigated for micro-slot grinding of BK7 glass. It is observed that micro-textured micro-grinding tool e?ciently serves the purpose of provisional chip collection in passive grinding areas of the tool whereas chip adhesion or wear on the active grinding areas signi?cantly gets reduced as compared to un-textured tools. Maximum reductions in the x and y direction forces are observed with tool type T5 compared to all other tool types. Reduction in z direction force is comparable for both tool types T2 and T3. Average surface roughness decreased from tool type T1 to type T2, T3 and up to tool type T4 whereas it again increased for tool type T5. The current study shows that textured micro-grinding tools are capable of reducing high normal forces, surface roughness and material dragging which are major concerns during micro-grinding with ?at-end poly-crystalline diamond tools.
关键词： Polycrystalline diamond tool,Micro-texture,Micro-grinding,BK7 glass,Surface roughness,Grinding force,Micro-EDM
更新于2025-09-09 09:28:46