Using a Panasonic MG-72 Micro Electro-Discharge Machine, techniques and procedures are developed to fabricate complex microstructures in conductive materials and engineered ceramics.

Ti-6Al-4V has a wide range of applications such as in the automotive and aerospace industries. Nevertheless, titanium alloys are very difficult to machine by conventional methods. Micro-EDM is a non-conventional machining method that uses the thermal effect of precisely controlled sparks. Manufacturers are looking for the methods and optimal settings to increase the productivity of micro-EDM in terms of lessening machining time and tool wear. Moreover, surface integrity of the machined area is crucial for some products such as biomedical implants. The objective of this study was to investigate the effects of the micro-EDM process parameters on response variables, in order to understand the behavior of each parameter as well as to determine their optimal values. Although, there is a substantial amount of literature studying different aspects of micro-EDM, most of them were designed based on the one-factor-at-a-time experiments instead of studying all factors, simultaneously. This research was conducted through a series of experiments using a full factorial design. An analysis of variance was employed to analyze the findings and to determine the effect and significance of each process parameters on the response variables. The process parameters included voltage, capacitance, electrode rotational speed, and electrode coating. Voltage and capacitance were studied separately as well as in combination in terms of the discharge energy. Response variables consisted of machining time, tool wear, crater size, microhardness, and element characterization. The surface morphology and element characterization were studied through the application of SEM and EDS analysis. The findings indicated that voltage had a decreasing effect on machining time, while it increased the crater size. Capacitance decreased machining time and tool wear. It had an increasing effect on the surface hardness. The effects of the TN-coating and electrode rotational speed were not statistically significant. Voltage and capacitance were the only parameters affecting element characterization. The affected elements included Ti, Al, C, and W. The optimal process parameters for two sets of response variables were determined using Minitab 17.

Capacitive sensors are frequently applied to curved target surfaces for precision displacement measurements. In most cases, these sensors have not been recalibrated to take the curvature of the target into consideration. This recalibration becomes more critical as the target surface becomes smaller in comparison to the sensor. Calibration data are presented for a variety of capacitance probe sizes with widely varying geometries. One target surface particularly difficult to characterize is the inner surface of small holes, less than one millimeter in diameter. Although contact probes can successfully measure the inner surface of a hole, these probes are often fragile and require additional sensors to determine when contact occurs. Probes may adhere to the wall of the hole, and only a small number of data points are collected. Direct capacitance measurement of small holes requires a completely new capacitance probe geometry and method of operation. A curved, elongated surface minimizes the gap between the sensor surface and the inner surface of the hole. Reduction in the size of the sensing area is weighed against electronics limitations. The performance of a particular probe geometry is studied using computer simulations to determine the optimal probe design. Multiple, overlapping passes are deconvolved to reveal finer features on the surface of the hole. A prototype sub-millimeter capacitance probe is machined from tungsten carbide, with four additional material layers added using ebeam deposition. Several techniques are studied to remove these layers and create a sensing area along one side of the probe. Both mechanical processes and photolithography are employed.

The purpose of this research was to investigate the surface modifications that take place during the machining of NiTi SMA and Ti-6Al-4V with micro-EDM. This was done by creating an array of blind holes and micro-patterns on both work-pieces. To analyze the machined surface and investigate the results, scanning electron microscope (SEM), energy dispersive X- ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques were employed. In addition, the effects of various operating parameters on the machining performance was studied to identify the optimum parameters for micro-EDM of NiTi SMA and Ti-6Al-4V. Recently, aerospace and biomedical industries have placed a high demand on nonconventional machining processes, which can be used to machine high strength and hardto- cut materials such as Titanium alloys, Shape Memory Alloys (SMA) and Super Alloys. Electrical Discharge Machining (EDM) is one of the non-traditional technologies that remove materials from the workpiece through a series of electrical sparks that occur between the workpiece and cutting tool with the presence of dielectric liquid. Obtaining smooth and defect-free surfaces on both workpieces was one of the challenges due to the re-solidified debris on the machined surface. The experimental results showed that there was significant amount of re-casting and formation of resolidification of debris on the Ti surface after machining. On the other hand, the surface generated in NiTi SMA were comparatively smoother with lesser amount of resolidified debris on the surface. By analyzing the results from XRD and EDS, some elements of electrode and dielectric materials such as Tungsten, Carbon and Oxygen were observed on NiTi and Ti surface after machining. In the study of effect of operating parameters, it was found that the voltage, capacitance and tool rotational speed had significant effect on machining time. The machining time was reduced by increasing the voltage, capacitance and tool rotational speed. The machining time was found to be comparatively higher for machining NiTi SMA than Ti alloy. Comparing all the parameters, the voltage of 60 V, capacitance of 1000 PF, and tool rotational speed of 3500 RPM were selected as optimum parameters for this study. Although signs of tool electrode wear and debris particles on the machined surface were observed for both workpieces during the micro-EDM process, Ti alloy and NiTi SMA could be machined successfully using the micro-EDM process.

Electrical Discharge Machining (EDM) is a non-traditional machining process that uses hundreds of thousands of minute electrical sparks per second to machine any electrically conductive material, no matter the hardness or how delicate it is. EDM allows a much greater range of design possibilities, unconstrained from the traditional machining processes, in which material is removed mechanically by either rotating the cutting tool or the work piece. Shapes that were impossible to machine by any other method, such as deep, precision, square holes and slots with sharp inside corners, are readily produced. It provides accurate geometries in high- aspect ratio holes and slots, blind undercuts, small holes adjacent to deep sidewalls, and complex cuts in thin, fragile parts. Micro-EDM is a growing form of manufacturing and will continue to expand within various production fields. Micro-EDM is especially attractive for the applications where the cutting time is minimal, but precision and accuracy are maximized. Micro- EDM is a non-traditional cutting process, which consistently produces ultra-precise holes with fine surface finishes and better roundness, while holding extremely close diameter tolerances. The process could be an excellent problem-solving tool for configurations that are difficult or impossible to produce using conventional machining processes. This study presents a comparative experimental investigation on the micro-EDM machinability of difficult-to-cut Ti-6Al-4V and soft brass materials. As both materials are electrically conductive, they were machinable using the micro-EDM process irrespective of their hardness. The machining performance of the two materials was evaluated based on the quality of the micro-features produced by the micro-EDM process. Both blind and through micro-holes and micro-slots were machined on brass and Ti-6Al-4V materials. The quality of micro-features was assessed based on the shape accuracy, surface finish and profile accuracy of the features. Finally, the arrays of micro-features were machined on both materials to compare the mass production capability of micro-EDM process on those materials.