scholarly journals Investigation on Bidirectional Pulse Electrochemical Micromachining of Micro Dimples

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1108
Author(s):  
Zhouzhi Gu ◽  
Xiaolei Chen ◽  
Zhongzheng Xu ◽  
Zhisen Ye ◽  
Guojun Li
Keyword(s):  
Duty Cycle ◽  
Pulse Frequency ◽  
Pulse Mode ◽  
Electrochemical Micromachining ◽  
Face To Face ◽  
High Pulse Frequency ◽  
Simulation And Experiment ◽  
Micro Dimples ◽  
Metallic Parts ◽  
Micro Dimple

Through-mask electrochemical micromachining (TMEMM) is a promising method to prepare micro dimples on the surface of metallic parts. However, the workpiece is machined one by one in traditional TMEMM. This paper introduced bidirectional pulse to TMEMM to improve the machining efficiency. Two masked workpieces were placed face to face, and connected to the ends of the bidirectional pulse power supply. Along with the change of the pulse direction, the polarities of the two workpieces were interchanged periodically, and micro dimples could be prepared on both workpieces at one time. The simulation and experiment results indicated that with bidirectional pulse mode, micro dimples with same the profile can be prepared on two workpieces at one time, and the dimension of micro dimple was smaller than that with unidirectional pulse mode. In bidirectional pulse current, the pulse frequency and pulse duty cycle played an important role on the preparation of micro dimple. With high pulse frequency and low pulse duty cycle, it is useful to reduce the undercut of micro dimple and improve the machining localization. With the pulse duty cycle of 20% and pulse frequency of 10 kHz, micro dimples with etch factor (EF) of 3 were well prepared on both workpieces surface.

Electrochemical micromachining of large-area micro-dimple arrays with high machining accuracy

2016 ◽  
Vol 232 (11) ◽  
pp. 1918-1927 ◽  
Author(s):  
Zhibao Hou ◽  
Ningsong Qu ◽  
Xiaolei Chen
Keyword(s):  
Duty Cycle ◽  
Applied Voltage ◽  
Electrical Discharge Machining ◽  
Electrochemical Micromachining ◽  
Machining Accuracy ◽  
Large Area ◽  
Machining Time ◽  
Pillar Arrays ◽  
Micro Dimples ◽  
Micro Dimple

Surface textures, especially micro-dimple arrays, can significantly improve the friction performance of engineering parts. Through-mask electrochemical micromachining is an effective method for generating micro-dimple arrays. In this article, a new method is introduced to fabricate a large-area polydimethylsiloxane mask containing micro through-holes. Using this technique, a stainless steel mould with micro-pillar arrays is generated by wire electrical discharge machining. A combination of pressure and weight of electrolyte is then proposed to keep the polydimethylsiloxane mask closely attached to the workpiece, which helps to achieve high machining accuracy. The effects of applied voltage, effective machining time and pulse duty cycle on the micro-dimples are investigated. The profiles of the micro-dimples are not sensitive to applied voltage, but pulse duty cycle is a significant factor influencing the depth of the micro-dimples. Micro-dimples of width 95 µm, depth 19 µm and a machining area of diameter 40 mm are successfully generated using a polydimethylsiloxane mask, and the standard deviations of the micro-dimple width and depth are only 0.84 and 0.23 µm, respectively. The present experiments verify that it is feasible to obtain large-area micro-dimple arrays with high machining accuracy using this technique.

Micro Dimple Fabrication on OFHC Copper by Laser Shock Processing

2012 ◽  
Vol 217-219 ◽  
pp. 2246-2251
Author(s):  
Kang Mei Li ◽  
Yong Xiang Hu ◽  
Zhen Qiang Yao
Keyword(s):  
Ofhc Copper ◽  
Laser Shock ◽  
Treatment Technology ◽  
Laser Shock Processing ◽  
New Process ◽  
Pile Up ◽  
Micro Dimples ◽  
Metallic Parts ◽  
Shock Processing ◽  
Micro Dimple

Micro dimples have been generally considered as a valuable texture which can improve lubrication and reduce wear of the sliding surfaces by acting as reservoirs of lubricants and grinding debris. Laser shock processing (LSP) is an innovative surface treatment technology which can modify metals and shape metallic parts accurately. In this study, a new process for micro dimple fabrication which could be called laser peen texturing (LPT) was proposed based on LSP. LPT experiments were performed on Oxygen-Free High Conductivity (OFHC) copper. Influences of experimental parameters on geometrical characteristics of micro dimples were investigated. It was found that after LPT, the pile up was generated around the dimple .The diameter, depth and aspect ratio of the micro dimples increase with the laser power density and repeated shock number, but all of them saturated gradually. From matellographic analysis, grain refinement was observed obviously beneath the dimple.

Fabrication of Micro-Dimple Arrays Using Modified Through-Mask Electrochemical Micromachining

2014 ◽  
Vol 703 ◽  
pp. 146-149 ◽  
Author(s):  
Qiao Ling Hao ◽  
Ping Mei Ming
Keyword(s):  
High Efficiency ◽  
Low Cost ◽  
Fluid Motion ◽  
Pulsed Power ◽  
Heat Transfer Fluid ◽  
Electrochemical Micromachining ◽  
Process Factor ◽  
Orthogonal Experiments ◽  
Micro Dimples ◽  
Micro Dimple

It has been found that well-defined surface textures (such as micro-dimple arrays, micro groove arrays) can reduce friction, wear and improve heat transfer, fluid motion state effectively. To produce micro-dimple arrays on the metal surface with a high efficiency and low cost, this paper proposed a modified through-mask electrochemical micromachining method with flexible porous material filled in the interelectrode gap. The feasibility of the process and the most important process factor which affects the depth of the micro-dimple were investigated by orthogonal experiments. The results showed that micro-dimple arrays can be obtained efficiently using both direct current (DC) and pulsed current and the qualities of the micro-dimples generated by pulsed power were much better than those formed by DC. Electrolyte concentration was the most important factor that affected the depth of the micro-dimple in the selected process parameters.

scholarly journals Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 122
Author(s):  
Catharina Latz ◽  
Thomas Asshauer ◽  
Christian Rathjen ◽  
Alireza Mirshahi
Keyword(s):  
Surgical Techniques ◽  
Numerical Aperture ◽  
Optical Breakdown ◽  
Pulse Frequency ◽  
Low Energy ◽  
Human Cornea ◽  
Energy Concept ◽  
High Pulse Frequency ◽  
Fs Laser ◽  
High Pulse

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

Effect of laser-textured micro dimples on inhibition of stick-slip phenomenon of sliding guideway

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yonghong Fu ◽  
Jie Yang ◽  
Hao Wang ◽  
Yuyang He
Keyword(s):  
Hydrodynamic Lubrication ◽  
Textured Surface ◽  
Stick Slip ◽  
Content Type ◽  
Speed Range ◽  
Lubrication Condition ◽  
Micro Dimples ◽  
Pin On Disk ◽  
Micro Dimple ◽  
Slip Phenomenon

Purpose This study aims to investigate the efficacy of micro dimple in inhibiting stick-slip phenomenon on the sliding guideway. Design/methodology/approach In this study, micro-dimples were fabricated by laser on surfaces of steel disk and guideway. The disks and guideways were respectively performed pin-on-disk tribological tests and working condition experiments to study differences in lubrication condition and friction stability between textured and untextured surfaces. Findings Micro-dimples help reduce critical sliding speed that allows contact surfaces to enter in hydrodynamic lubrication regime. This increases hydrodynamic lubrication range and narrows speed range where stick-slip phenomenon can occur, enhancing sliding guideway’s adaptability for broader working conditions. Furthermore, friction stability on the textured surface improved, lowering the occurrence possibility of stick-slip phenomenon. Finally, difference between static and kinetic frictions on the textured surface is lower relative to the untextured surface, which decreases the critical velocity when the stick-slip phenomenon occurs. Originality/value The results indicate that laser-textured micro-dimples are significantly conducive to inhibit stick-slip phenomenon, thus providing smoother movement for the guideway and eventually increasing precision of the machine.

scholarly journals Fabrication of array of micro circular impressions using different electrolytes by maskless electrochemical micromachining

2020 ◽  
Vol 7 ◽  
pp. 15 ◽  
Author(s):  
S. Kunar ◽  
E. Rajkeerthi ◽  
K. Mandal ◽  
B. Bhattacharyya
Keyword(s):  
Experimental Investigation ◽  
Cross Flow ◽  
Surface Characteristics ◽  
Pulse Frequency ◽  
Electrochemical Micromachining ◽  
Duty Ratio ◽  
Mixed Electrolyte ◽  
Radial Overcut ◽  
Cell Electrode ◽  
Electrical Connections

Maskless electrochemical micromachining (EMM) is a prominent technique for producing the array of micro circular impressions. A method for producing the array of micro circular impressions on stainless steel workpiece applying maskless electrochemical micromachining process is presented. The experimental setup consists of maskless EMM cell, electrode holding devices, electrical connections of electrodes and constricted vertical cross flow electrolyte system to carry out the experimental investigation. One non-conductive masked patterned tool can produce more than twenty six textured samples with high quality. A mathematical model is developed to estimate theoretically the radial overcut and machining depth of the generated array of micro circular impressions by this process and corroborate the experimental results. This study provides an elementary perceptive about maskless EMM process based on the effects of EMM process variables i.e. pulse frequency and duty ratio on surface characteristics including overcut and machining depth for NaCl, NaNO3 and NaNO3 + NaCl electrolytes. From the experimental investigation, it is observed that the combined effect of lower duty ratio and higher frequency generates the best array of micro circular impressions using the mixed electrolyte of NaNO3 + NaCl with mean radial overcut of 23.31 µm and mean machining depth of 14.1 µm.

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