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Electrohydrodynamic (EHD) inkjet is a modern non-contact printing approach, which uses a direct writing technology of functional materials to achieve micro/nanoscale of printing resolution. As an alternative to conventional inkjet technology, the goal of the EHD inkjet printing is to generate uniformly minimized droplets on a substrate. In this study, the effects of applied voltage, standoff height and ink flow rate on droplet diameter formation in EHD inkjet printing process were analysed using Taguchi methodology and regression analysis. Several experiments were carried out using an L 27 (3 13) orthogonal array. Based on signal to noise (S/N) ratio and mean response, optimal droplet diameter was achieved. The analysis of variance (ANOVA) was used to find the significance and percentage of contribution of each input parameter along with their interaction on the output droplet diameter. Analysis of the results revealed that the ink flow rate was the dominant factor that affected the droplet diameter mostly. The effect of the applied voltage is significant until regular ejection starts. It helps reduce droplet diameter more than five times compared with its initial droplet diameter in the absence of the electric field. A confirmation test was carried out with a 90% confidence level to illustrate the effectiveness of the Taguchi optimization method. Both linear and quadratic regression analysis were applied to predict the output droplet diameter. The predicted result from the model and actual test results are very close to each other, justifying the significance of the models. Keywords. Electrohydrodynamic (EHD) inkjet printing; design of experiments (DOE); Taguchi method; analysis of variance (ANOVA).

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Application of Micro-Nano scale Electrical Discharge Machining is rapidly growing in manufacturing of metal products irrespective of its hardness having geometric features in range of micrometer to nanometer scale. To achieve such small geometrical features, smaller dimensional tool electrode is required. However fabrication of this tiny electrode with desired dimension and also handling of such tiny electrodes is a primary aspect that needs to be investigated systematically to use the Micro-Nano scale EDM in batch production of micro parts. In this work authors investigate the application of electrochemical etching process for fabricating EDM electrodes smaller than 10 µm. While the smallest electrode fabricated with the optimized parameter is 3.33 µm, their performance as electrode in micro-EDM has been studied systematically. To the best of authors’ knowledge such studies are not reported in the published literatures. However, the fabrication of such smaller size features by applying alternating current in ECE has been attempted previously but not for micro-EDM applications.

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