Micro reciprocated wire-EDM of micro-rotating structure combined multi-cutting strategy

This paper presents the manufacture of micro-rotating structure combining micro reciprocated wire electrical discharge machining (wire-EDM) and multi-cutting strategy. A novel rotating spindle is developed to achieve the rotation of cylindrical workpiece and the multi-cutting strategy including rough, semi-finish, and finish machining is attempted to improve the machining removal rate (MRR) and reduce the surface roughness (SR) of micro-rotating structure. To determine proper parameters for multi-cutting process, the effects of machining parameters such as open voltage, discharge capacitance, and rotation rate on MRR and SR are studied by systematically performing experiments planed by single factor design and central composite design (CCD) of response surface methodology (RSM). Analysis of variance (ANOVA) is conducted to identify the significant factor and confirm the adequacy of the established models of MRR and SR. The mathematical models are used to predict MRR and SR within 8.18 and 8.74% prediction error compared with the additivity tests, respectively. Desirability method in RSM technique is used to determine three sets of parametric combinations for multi-cutting process, which are verified by confirmation experiments with 1.75~7.76% prediction error for MRR and 2.77~8.59% prediction error for SR. Finally, a typical microballoon probe is successfully machined with 0.435 Ra and 98.7-μm diameter by the proposed method, which provides a feasible approach for the fabrication of micro-rotating structure with high efficiency and smooth surface.