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.

A Review of Surface Texturing in Internal Combustion Engine Piston Assembly

“…Chen et al [69] had applied the ECM method with TMEMM technic together with a PDMS mask and successfully produce micro dimple array on a cylindrical surface. These studies show improvement in friction coefficient [64,74] and wear [60] with fabricated micro dimples as well as able to produce a different type of micro dimple shapes [63,[60][61]. However, there is still a lack the studies of tribological behavior of ECM produced micro dimples.…”

“…Many of the studies recently focus on producing micro dimple array instead of single dimple [62]. Many technics have emerged such as maskless electrochemical texturing (MECT) [60,63], through-mask electrochemical micromachining (TMEMM) [58,62,[64][65][66][67], using Polydimethylsiloxane (PDMS) mask [59,61,[68][69][70][71], sandwich-like electrochemical micromachining (SLEMM) [72][73] and others [74]. Chen et al [69] had applied the ECM method with TMEMM technic together with a PDMS mask and successfully produce micro dimple array on a cylindrical surface.…”

The Effect of Electrolytic Jet Orientation on Machining Characteristics in Jet Electrochemical Machining

“…In order to analyze the effect of the jet orientation on the geometric dimensional accuracy of the micro-dimples, the diameter, depth (maximum), aspect ratio (depth/diameter), and the etch factor (EF) of the machined micro-dimples fabricated with different machining modes were calculated. Here, EF is introduced to further characterize the machining localization, which is frequently used in through-mask electrochemical machining [26]. EF is defined for the electrolytic jet machining processes as follows: EF = 2h/(d − d 0 ) where h is the maximum depth of the machined microstructures, d 0 is the inner diameter of the nozzle, and d is the diameter of the machined micro-dimple.…”

Ultrasound-Assisted Through-Mask Electrochemical Machining of Hole Arrays in ODS Superalloy

“…To further improve mask performance, Kunar et al [ 12 ] reported a new reusable masked tool to fabricate a micro square pattern by ECM and obtained ideal results. On the other hand, Mahata et al [ 13 ] proposed a novel process for micro-dimple arrays by TMECM with low-aspect ratio masks that could promote the quality of micro-dimple arrays and save expenditure for a thick mask. Though TMECM has been successfully used in micro-hole array processing, some serious problems such as the consistent precision of large-scale machining and stray-current corrosion remain unsolved.…”

“…ECM ensures a higher stability of the machining process without the heat-affected zone generation, machining stress, and the limitation of material hardness [7,8]. As an ECM technology, through-mask ECM (TMECM) is primarily intended for micro-hole array processing with restraining the machinable region by using a thin insulation sheet with a specific pattern, and TMECM has been widely used to produce micro-structured components Materials 2020, 13, 5780 2 of 13 such as micro-dimples, hole arrays and micro-grooves. The research focuses of TMECM include the analysis of the forming process, the optimization of mask characteristics, and the improvement of electrolyte exchange [9].…”