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.

scholarly journals Fabrication of various micropatterns by maskless micro-electrochemical texturing

2019 ◽  
Vol 6 ◽  
pp. 6 ◽  
Author(s):  
Sandip Kunar ◽  
Bijoy Bhattacharyya
Keyword(s):  
Flow Rate ◽  
Cross Flow ◽  
Pulse Frequency ◽  
Electrochemical Micromachining ◽  
Duty Ratio ◽  
Machining Accuracy ◽  
Machining Time ◽  
Interelectrode Gap ◽  
Set Up ◽  
Cell Electrode

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.

Influence of electrolytes on surface texture characteristics generated by electrochemical micromachining

2018 ◽  
Vol 1 (2) ◽  
pp. 124-133 ◽  
Author(s):  
Sandip Kunar ◽  
S. Mahata ◽  
B. Bhattacharyya
Keyword(s):  
Flow Rate ◽  
Surface Engineering ◽  
Pulse Frequency ◽  
Electrochemical Micromachining ◽  
Duty Ratio ◽  
Machining Time ◽  
Novel Approach ◽  
Best Parameter ◽  
Work Samples ◽  
Set Up

Generation of microsurface texture is an important technology for surface engineering that can produce a significant improvement of engineering components in aspects to wear resistance, friction coefficient, load capacities, part lubrication, etc. This research proposes a novel approach of maskless electrochemical micromachining (EMM), which is anodic dissolution based on electrochemical reaction. One reused textured cathode tool with patterned SU-8 2150 mask can fabricate many work samples economically with less time. Maskless EMM set-up with developed EMM cell and vertical crossflow electrolyte supply system is used to generate micro circular patterns on stainless steel (SUS 304) using three different types of electrolytes such as NaCl, NaNO3 and NaCl + NaNO3. The influences of major process parameters such as interelectrode gap (IEG), flow rate, machining time and electrolyte concentration on mean radial overcut and mean machining depth have been investigated using these electrolytes. Out of these three electrolytes, only NaCl + NaNO3 of 20 g l−1 is selected as the best electrolyte with other best parameter settings such as applied voltage of 12 V, duty ratio of 30%, pulse frequency of 5 kHz, flow rate of 3.12 m3 hr−1, IEG of 50 µm and machining time of 3 minutes for generating good textured characteristics with overcut of 27.581 µm and depth of 15.1 µm. Analyses have also been done to investigate the textured characteristics using these electrolytes for acquiring the best parametric combination with suitable electrolyte.

scholarly journals Improvement of Surface Quality and Machining Depth of µ-ECDM Performances Using Mixed Electrolyte at Different Polarity

2021 ◽  
Author(s):  
BIJAN MALLICK ◽  
B R SARKAR ◽  
B DOLOI ◽  
B BHATTACHARYYA
Keyword(s):  
Surface Quality ◽  
Pulse Frequency ◽  
Sem Analysis ◽  
Machining Process ◽  
Duty Ratio ◽  
Tool Electrode ◽  
Electrode Wear ◽  
Micro Channel ◽  
Reverse Polarity ◽  
Mixed Electrolyte

Abstract The production of miniature parts and various shape of micro-profile by electrochemical discharge micro-machining process (µ-ECDM) draw challenging attention to the researchers. Parametric influences as well as comparative analysis on machining depth (MD) and surface roughness (Ra) has been propounded using NaOH and KOH at the ratio of 1:0, 3:1, 1:1, 1:3 and 0:1 with their varying concentration(wt.%), and applied voltage (V), pulse frequency(Hz) and duty ratio (%)in straight as well as in reverse polarity using template guided stainless steel (SS) cylindrical tool with motion and spring feed mechanism for fabrication of different shapes of micro-channel like Zig-Zag, ‘Y’ shaped on glass by µ-ECDM process. Tool electrode wear rate (TEWR) has been reduced using mixed electrolyte and reversed polarity. The SEM analysis has been performed to identify the micro-crack and uncut debris into micro-channel. Machining depth has been increased up to 1850 µm with better surface quality using mixed electrolyte of NaOH:KOH::3:1 at direct polarity of 50 V and lower TEWR is found using NaOH:KOH::1:3 as electrolyte at reverse polarity.

An Experimental Investigation of the Dynamics of a Loosely Supported Tube Array

2017 ◽  
Author(s):  
Amro Elhelaly ◽  
Marwan Hassan ◽  
Atef Mohany ◽  
Soha Moussa
Keyword(s):  
Experimental Investigation ◽  
Impact Force ◽  
Cross Flow ◽  
Open Loop ◽  
Diameter Ratio ◽  
Force Level ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
System Integrity ◽  
Tube Bundles

The integrity of tube bundles is very important especially when dealing with high-risk applications such as nuclear steam generators. A major issue to system integrity is the flow-induced vibration (FIV). FIV is manifested through several mechanisms including the most severe mechanism; fluidelastic instability (FEI). Tube vibration can be constrained by using tube supports. However, clearances between the tube and their support are required to allow for thermal expansion and for other manufacturing considerations. The clearance between tubes may allow frequent impact and friction between tube and support. This in turn may cause fatigue and wear at support and potential for catastrophic tube failure. This study aims to investigate the dynamics of loosely supported tube array subjected to cross-flow. The work is performed experimentally in an open-loop wind tunnel to address this issue. A loosely-supported single flexible tube in both triangle and square arrays subjected to cross-flow with a pitch-to-diameter ratio of 1.5 and 1.733, respectively were considered. The effect of the flow approach angle, as well as the support clearance on the tube response, are investigated. In addition, the parameters that affect tube wear such as impact force level are presented.

Experimental Investigation of Vortex-Induced Vibrations of a Flexibly Mounted Circular Cylinder in Combined Current and Wave Flows

2021 ◽  
Author(s):  
Pierre-Adrien Opinel ◽  
Narakorn Srinil
Keyword(s):  
Experimental Investigation ◽  
Circular Cylinder ◽  
Cross Flow ◽  
Wave Flow ◽  
Regular Wave ◽  
Regular Waves ◽  
Vortex Induced Vibrations ◽  
Flow Frequency ◽  
The Cross ◽  
Wave Flows

Abstract This paper presents the experimental investigation of vortex-induced vibrations (VIV) of a flexibly mounted circular cylinder in combined current and wave flows. The same experimental setup has previously been used in our previous study (OMAE2020-18161) on VIV in regular waves. The system comprises a pendulum-type vertical cylinder mounted on two-dimensional springs with equal stiffness in in-line and cross-flow directions. The mass ratio of the system is close to 3, the aspect ratio of the tested cylinder based on its submerged length is close to 27, and the damping in still water is around 3.4%. Three current velocities are considered in this study, namely 0.21 m/s, 0.29 m/s and 0.37 m/s, in combination with the generated regular waves. The cylinder motion is recorded using targets and two Qualisys cameras, and the water elevation is measured utilizing a wave probe. The covered ranges of Keulegan-Carpenter number KC are [9.6–35.4], [12.8–40.9] and [16.3–47.8], and the corresponding ranges of reduced velocity Vr are [8–16.3], [10.6–18.4] and [14–20.5] for the cases with current velocity of 0.21 m/s, 0.29 m/s and 0.37 m/s, respectively. The cylinder response amplitudes, trajectories and vibration frequencies are extracted from the recorded motion signals. In all cases the cylinder oscillates primarily at the flow frequency in the in-line direction, and the in-line VIV component additionally appears for the intermediate (0.29 m/s) and high (0.37 m/s) current velocities. The cross-flow oscillation frequency is principally at two or three times the flow frequency in the low current case, similar to what is observed in pure regular waves. For higher current velocities, the cross-flow frequency tends to lock-in with the system natural frequency, as in the steady flow case. The inline and cross-flow cylinder response amplitudes of the combined current and regular wave flow cases are eventually compared with the amplitudes from the pure current and pure regular wave flow cases.

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