Micro-dimple arrays are among the basic microfeatures that plays an important role in performance and reliability enhancement of mechanical systems. The presence of micro-dimples on the workpiece surfaces has been known to have positive impact on the friction control and wear resistance of sliding surfaces. Although several manufacturing processes have been employed to generate micro-dimples on the workpiece surfaces, it is still a challenge to generate micro-dimples utilizing a low-aspect-ratio mask by Through Mask Electrochemical Micromachining (TMEMM). In this paper, AZ-4903 is introduced as a mask due to its availability, low cost as well as chemical resistance. A novel approach of TMEMM is proposed in which very thin masks were used for generation of micro-dimple arrays. Experiments were conducted to study the influence of duty ratio on the machining accuracy and surface properties of the generated micro-dimples. Micro-hole array with an average diameter of 65 μm imprinted on the mask are successfully replicated over SS304 substrate with considerable repeatability. Micro-dimple arrays measuring an undercut of 29.15 μm, depth 32.15 μm and 0.091 μm Ra was successfully fabricated in this study. Moreover, friction test results show that surfaces possessing appropriate micro-dimple array are highly beneficial in reducing frictional co-efficient as compared to smooth surfaces.
In this paper, an innovative and alternative concept of maskless micro-electrochemical texturing is exploited for the fabrication of simple and complex micropatterns. In this process, the tool is masked incorporated with the textured patterns and the workpiece has no mask. This research study concentrates on generation of simple micropattern, i.e. linear micropattern, and complex micropattern, i.e. cascade micropattern using maskless micro-electrochemical texturing method without repeated use of photolithography process. A single masked patterned tool with SU-8 2150 mask can produce many high-quality simple and complex micropatterns economically using this method. A well-planned experimental set-up consisting of electrochemical micromachining (EMM) cell, electrode fixtures, electrical connections and constricted vertical cross-flow electrolyte system has been designed and developed indigenously for carrying out the experiments. Influences of major influencing parameters, i.e. machining voltage, interelectrode gap, flow rate and machining time, are investigated on width overcut and machining depth of micropatterns. For higher machining accuracy, controlled depth and lower standard deviations, machining with lower machining time, lower voltage, lower interelectrode gap and higher flow rate is recommended. From the detailed experimental investigation, the best parametric combination are voltage of 8 V, duty ratio of 30%, pulse frequency of 15 kHz, electrolyte of NaCl (0.34 M) + NaNO3 (0.23 M), flow rate of 5.35 m3/h, interelectrode gap of 50 µm and machining time of 40 s.
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