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This article is about the implementation of an acquisition system for the measurement of micro-electro discharge machining process parameters and the statistical analysis of their influence on the process performance. The microelectro discharge machining drilling of 316L stainless steel with copper tubular electrodes was studied and the exchanged power was taken into account as a comprehensive variable able to represent the effect of the peak current and voltage on the final result. The direct proportionality between the exchanged power and the nominal process parameters was verified. A linear and non-linear regression approach was used in order to obtain predictive equations for the most important aspects of micro-electro discharge machining process, such as the machining time and the electrode wear.

The aim of this work is to analyse the influence of electrode material in micro-EDM drilling of stainless steel and tungsten carbide metal plates. Brass and tungsten carbide electrodes were selected basing on their different electrical and thermal properties. The experimental campaign was based on the execution of a large number of micro-holes carried out by varying some process parameters, namely peak current, voltage and frequency. Tool wear ratio and material removal rate were assumed as process performance indexes, while diametral overcut and taper rate were considered as geometric indexes. The Analysis of Variance (ANOVA) was applied on the results coming out from the experiments. Moreover, a overall Process Index based on both process parameters and electrode material properties was proposed. This index fits, with a good correlation level, all the process performance and geometric indicators for both the considered workpiece materials. A comparison between the performance measured using stainless steel and tungsten carbide workpieces was also carried out. The results of this experimental research showed that electrical resistivity, thermal conductivity and melting point of both electrode and workpiece materials have a significant effect on the process and geometric performance.

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After a first period in which the research has been focused on the optimisation of the process parameters, the attention is now focused on aspects that were usually neglected. However, they are very important in order to understand the physics of the waterjet / abrasive waterjet cutting process and to improve the cutting quality.Particularly, it has been demonstrated that, in the pure waterjet cutting (and in the abrasive waterjet cutting too), there are irregularities, called striations, along the generated surface. The striation formation depends mainly on the jet instability caused by vibrations during the cutting process. Vibration signals have been measured whilst varying the cutting conditions. A model has been studied which estimates the mean spacing and the frequency of the striations, as a function of the period and the amplitude of the jet vibration. This model has been completely validated through measurements of plasticine surfaces generated by waterjet cutting.