Micro Dimple Array Fabrication by Through Mask Electrochemical Micromachining Utilizing Low-Aspect Ratio Mask

Abstract

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.