1. bookVolume 39 (2021): Issue 1 (March 2021)
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access type Open Access

Experimental investigation of the electrochemical micromachining process of Ti-6Al-4V titanium alloy under the influence of magnetic field

Published Online: 09 Jul 2021
Page range: 124 - 138
Received: 25 Feb 2021
Accepted: 03 May 2021
Journal Details
License
Format
Journal
First Published
16 Apr 2011
Publication timeframe
4 times per year
Languages
English
Abstract

An attempt has been made to study the influence of magnetic field on the micro hole machining of Ti-6Al-4V titanium alloy using electrochemical micromachining (ECMM) process. The presence of magneto hydro dynamics (MHD) is accomplished with the aid of external magnetic field (neodymium magnets) in order to improve the machining accuracy and the performance characteristics of ECMM. Close to ideal solution for magnetic and nonmagnetic field ECMM process, the parameters used are as follows: concentration electrolyte of 15 g/l; peak current of 1.35 A; pulse on time of 400 s; and duty factor of 0.5. An improvement of 11.91–52.43% and 23.51–129.68% in material removal rate (MRR) and 6.03–21.47% and 18.32–33.09% in overcut (OC) is observed in ECMM of titanium alloy under the influence of attraction and repulsion magnetic field, respectively, in correlation with nonmagnetic field ECMM process. A 55.34% surface roughness factor reduction is ascertained in the hole profile in magnetic field-ECMM in correlation with electrochemical machined titanium alloy under nonmagnetic field environment. No machining related stress is induced in the titanium alloy, even though environment of electrochemical machining process has been enhanced with the presence of magnetic field. A slight surge in the compressive residual factor, aids in surge of passivation potential of titanium alloy, resulting in higher resistance to outside environment.

Keywords

Introduction

The prime and fundamental process involved in manufacturing smart/digital devices or any machinery is micromachining, which is performed to creating thin film patterns. In this regard, electrochemical micromachining (ECMM) is found to be a promising method for the production of accurate and precise features (micro in nature) for a broad range of conducting materials [1]. It holds its ground in the non-conventional areas due to its fine surface finish, negligible thermal effects, and lack of residual stress in the workpiece [2]. It is extensively used to produce/fabricate parts that are very complex in shape despite their predominant hardness value [3]. In ECMM, anodic dissolution of metal occurs in the presence of electrolytic solution and this process follows the principle of Faraday's law of electrolysis [4].

Researchers have carried out work in the areas of pulse ECM, insulated tool ECM, vibration assisted tool ECM, and masking of workpiece [5] to improve the overall efficiency of the system [6]. A substantial improvement was experienced in mass transport by using a vibrating workpiece and a traveling wire which were manufactured by ECMM [7]. Eylon et al. [8] and Xu et al. [34] have considerably enhanced mass transport and electrolyte refreshment by enhancing cathode hydrophilicity [9]. Researchers proposed a technique which uses sinusoidal electrical signals in ECMM that are readily available and further eliminates the use of an expensive ultra-short pulse power source [10]. Laser-assisted jet ECM (JECM) was developed indigenously and its performance was compared with JECM; the experimental outcomes reported that the material removal rate (MRR) increased by 29.16% and the taper angle abated by 48.43% [11]. Magnetic field-assisted ECM is a process, where the magnetic line is orthogonal to the electrolyte stream path firming up the mass transfer rate and effectively reducing stray corrosion, thus there is no deterioration in the electrolytic processing flow field which resulted in improved surface roughness of the workpiece [12]. ECM found its application in the automobile and aviation industries in the production of fuel injection holes for car engines [7] and cooling holes in turbine blades [8]. Bhattacharyya et al. [9] availed ECMM for removal and patterning of thin films. With a wide spread changes occurring in micro scale, ECMM found its strong footing in miniature production cycles which hold a lot of economical weightage and with parts becoming smaller and finer, the need for ECMM has increased predominantly.

Titanium alloys have wide application in the sector of aerospace, marine, automobile industries owing to its excellent properties of higher tensile strength, corrosion resistance, and low modulus of elasticity [13]. But, machining such a multi-characteristic titanium alloy leads to colossal problems owing to long chip formation [14], minimal heat dissipation [15], and tensile residual stress formation [16] which affects the quality of the product [16]. In this regard, ECMM provides an apt solution for overcoming adverse effects, i.e., recast layer, cracking (micro in nature) and heat affected zone produced by other machining process [17]. Ti-6Al-4V is mainly availed for manufacturing blisks of high pressure air compressor [18]. Also, because of its nature of being biocompatible, Ti alloys are availed for dental implants, biomedical and health care products [19]. The roughness obtained in the oxide layered machined surface by ECMM process was suitable for use in titanium implants without any need for further surface preparation, owing to the fact of osseointegration [20].

Scientists and researchers carried out work and focused their efforts to improve the surface integrity of machined Ti-6Al-4V, thereby enhancing MRR and other associated machining parameters, and Lu and Leng [21] employed jet ECMM for achieving that. For mass production of Philips domestic and personal care products, ECMM was utilized to improve the overall productivity [22]. MRR plays a vital role in increasing the productivity and because of this great factor, it would get greater acceptance in all industry bodies involved manufacturing of micro and macro samples. Hinds at al. [23] studied the effect of magnetic field on copper electrolysis. It was ascertained that metal deposition surges by improving chemical reaction, in magneto electrolysis. Similarly, effect of magnetic field on electrolyte properties was studied by Fahidy [24], and Mohanta and Fahidy [25] simulated the effect of magnetic field on anodic dissolution amount in ECMM process [26]. In this work, influence of magnetic field on ECMM process is carried out for micro hole machining of titanium alloy (Ti-6Al-4V). The presence of magneto hydro dynamics (MHD) is accomplished with the aid of external magnetic field in order to improve the machining accuracy and the performance characteristics of ECMM.

Materials and methods
Experimental setup and practice

A micro ECMM setup, developed for carrying out the research is depicted in Figure 1. It consists of stepper motor with a tool feed mechanism, a working tank with electrode fixing apparatus and a submergible pump with tube for flushing arrangement.

Fig. 1

Experimental setup for ECMM. ECMM, electrochemical micromachining.

The experiment uses water with sodium nitrite as electrolyte, as sodium nitrite has no passive reaction with the surface of the workpiece. The inter-electrode narrow gap was maintained at 30 m between the microtool and workpiece to assure a stable metal removal in micromachining of titanium alloy. Electrode end gap is maintained at minimal value so as to obtain colossal anodic dissolution, as localization of the dissolution process increases with low gap width [9]. A direct method is utilized to monitor the gap between the upon the propagation delay through the electrolyte between the microtool–electrolyte interface and workpiece surface–electrolyte interface. A cross reference is obtained by indirect gap measurement by computing and subtracting the micro tool face position from the workpiece height referenced to the same origin [13]. As the gap is predominantly small, mass and charge transfer kinetics tend to become complex causing indeterminacy in the reaction mode, which influences the current efficiency and in turn affects the MRR and accuracy [33]. The establishment of stable gap between electrodes is influenced by various major ECMM parameters such as applied voltage, type, concentration of electrolyte, gap voltage, and the process parameters and their levels for performing the experiment are indicated in Table 1.

Experimental details of ECMM setup.

System working condition
Parameters Range
Working voltage 150 V DC
Gap voltage 0–10 V
Electrolyte NaNO3 + Water
Magnets Neodymium 40 × 20 × 10 mm
Tool Copper: ϕ 0.6 mm
Workpiece Ti-6Al-4V: 30 × 10 × 0.1 mm
Process parameters
Process parameters Symbols Levels
Peak current (mA) Ip 1.2 1.35 1.5
Pulse on time (ms) Ton 300 400 500
Duty factor DF 0.5 0.6 0.7
Concentration of electrolyte (%) C 15 22 5 30

ECMM, electrochemical micromachining.

Variable rectangular DC pulsed supply in the range of microsecond pulse period was used for experimentation. The MRR and accuracy were observed for various sets of experiments with different combinations of process parameters. Micro tool feed rate was maintained as low as possible i.e., 2.4 m/s through control unit, which is most appropriate value for the existing EMM set up to enhance the micromachining accuracy [8]. The ratio of "pulse on time" to total pulse cycle time (sum of pulse on time and pulse off time) is termed as duty factor, which is taken at 50%, 60%, and 70% to form an appropriate flushing time to ensure proper linear dissolution takes place [7]. Orthogonal L27 array is utilized for experimental design. Before carrying out experimental analysis, the workpiece was machined to the dimensions mentioned and weighed (GR-202 with 0.0001 accuracy) before and after the experiments. No tool wear is ascertained in ECMM. The tool creates an inverse profile on the workpiece. The tool was designed and machined (circular profile edge: grounded) to ensure reduction in uneven edges for the circular hole profile to be created on the titanium alloy. Neodymium magnets (Nd-Fe-B) were used for the experimental work. The strength of the magnet and the field variation between the two magnets (both attraction and repulsion forces) were measured by using a gauss meter shown in Figure 2.

Fig. 2

Magnetic field measurement of magnets using gauss meter.

Further, experiments with attraction and repulsion forces of magnets have been carried out to understand the impact of the magnetic field on the machining cycle. The pictorial representation of the experimental setup along with magnets is shown in Figure 3.

Fig. 3

Placement of magnets in the machining cycle.

Moreover, the magnets were kept at a constant and equal distance from the tool center to ensure the repeatability of experiments conducted. Each specimen was weighed after all the experiments to ensure that continuous monitoring is carried out. The images of the machined hole are further captured and close to ideal experiment are studied by disparate characterization techniques to understand the effect of magnetic field on the machining cycle.

Magnetic field effect in electrolysis

From the Faraday's law of electrolysis, the mass of the substance (m) deposited/liberated at any electrode is directly proportional to the quantity of electricity or the charge (q) passed as indicated in Eq. (1).

mαq m\alpha q

It further creates an electric field density (E) on charged particles. When the magnetic fields B are applied perpendicular to the current carrying conductor, it experiences a force on the charged particle and is indicated as Lorentz's force (FL), as indicated in Eq. (2).

FL=q(E+ν×B) {F_L} = q\left({E + \nu \times B} \right)

This force causes the momentum transfer from the magnetic field driven ions to the neighboring solute molecules, giving rise to electrolyte convection resulting to a turbulence effect. This effect is indicated as MHD, which causes rapid movement of ion particles in helical orbits in the direction of Lorentz force and thus forces electrolyte movement. It affects bubble as well as ionic movement along with direction. Thus, in the presence of a magnetic field, mobility and direction of ions surge to a colossal extent. The net resultant force (FR) is given by, FR=γE+JΛB {F_R} = \gamma E + J\Lambda B where, J is the current density, a combination of conduction (JQ) and convection current (JC) and is stated as follows. J=JQ+ρCV J = {J_Q} + {\rho _C}V where ρC is the charge density due to convention. The flow of electrolyte in the presence of magnetic field causes positive and negative ions to get separated and thereby creating an electric field. This is based on the Hall effect phenomenon. Hence, the total electric field (Eq. 5) is the sum of electric fields due to self-induced and Hall effect. The Hall constant can be obtained through the solid state charge carrier which is expressed in Eq. (6). E=j/σRH(j×B) E = j/\sigma - {R_H}\left({j \times B} \right) RH=1n|e|(t+2h+t2h) {R_H} = {1 \over {n\left| e \right|}}\left({t_ + ^2{h_ +} - t_ - ^2{h_ -}} \right) where n is the number of electrons and e is the charge of the electron, in which t+ and t are cationic and anionic transference numbers respectively, h+ and h are the Hall numbers which denotes the ratio of the mobility of the positive/negative charge carriers in the magnetic field to the magnitude of same in the absence of the magnetic field. From Eqs (1)(6), it is evident that there exists a mutual interaction between the electric field, magnetic field, and flow field. The ohm's law couples the dynamics of flow field and the electromagnetic field which is given by, J+J×ωτ=σ(E+ν×B) J + J \times \omega \tau = \sigma \left({E + \nu \times B} \right) where ωτ = eB/meVc is a scalar representation of Hall parameter and σ = nee2/meVc, the electrical conductivity, e = electron charge, ne = number of electrons, me = electronic mass, Vc = electron collision frequency.

The magnetic field effect is not limited to reaction kinetics, anodic dissolution, movement, and direction of gas bubbles but also to the mass transport rate. The evidence of enhancement is due to the MHD effect with convective diffusion process. The mass transport rate is directly proportional to the current density and is given by, JA=zF1tA(VCADgradCA) {J_A} = {{zF} \over {1 - {t_A}}}\left({V{C_A} - {DgradC}_A} \right) where z = ionic valency, F = Faradays constant, V = velocity vector, CA = concentration, and D = electrolyte diffusivity.

It is ascertained from the theoretical analysis that the magnetic field in the electrochemical machining process plays a vital role in increasing the charge transfer rate by turning laminar flow of electrolyte into turbulent flow, thereby influencing the ionic and gas bubble movement and direction. To understand the same, experiments were carried out on titanium alloys using ECMM under the influence of magnetic field.

ECMM experiments in disparate environmental conditions

Orthogonal (L27) array is utilized to evaluate and conduct the experiment for magnetic (both attraction and repulsion) and nonmagnetic field ECMM conditions. The parameters under consideration are MRR and overcut (OC) in correlation with concentration of electrolyte, peak current, time on, and duty factor. The experimental values pertaining to electrochemical micromachining are tabulated in Table 2.

Orthogonal array experiment (L27) for magnetic and nonmagnetic field ECMM of Ti-6Al-4V titanium alloy.

No magnetic force Attraction magnetic force Repulsion magnetic force
S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF MRR 10−3 (mm3/min) OC (mm) MRR 10−3 (mm3/min) OC (mm) MRR 10−3 (mm3/min) OC (mm)
1 15 1.20 300 0.5 0.59 0.32 0.66 0.25 0.72 0.21
2 15 1.20 300 0.5 0.59 0.32 0.66 0.25 0.73 0.21
3 15 1.20 300 0.5 0.59 0.32 0.66 0.26 0.73 0.22
4 15 1.35 400 0.6 0.97 0.35 1.48 0.31 2.22 0.28
5 15 1.35 400 0.6 0.97 0.35 1.47 0.31 2.22 0.28
6 15 1.35 400 0.6 0.96 0.35 1.47 0.31 2.21 0.28
7 15 1.50 500 0.7 0.72 0.33 0.88 0.28 1.46 0.24
8 15 1.50 500 0.7 0.72 0.33 0.88 0.28 1.46 0.24
9 15 1.50 500 0.7 0.72 0.33 0.87 0.28 1.47 0.24
10 22.5 1.20 400 0.7 0.60 0.43 0.68 0.39 0.78 0.34
11 22.5 1.20 400 0.7 0.59 0.43 0.68 0.39 0.79 0.35
12 22.5 1.20 400 0.7 0.59 0.43 0.68 0.39 0.79 0.34
13 22.5 1.35 500 0.5 0.72 0.32 0.89 0.27 1.50 0.23
14 22.5 1.35 500 0.5 0.73 0.32 0.87 0.27 1.52 0.24
15 22.5 1.35 500 0.5 0.73 0.32 0.89 0.26 1.51 0.23
16 22.5 1.50 300 0.6 0.62 0.30 0.72 0.24 0.85 0.22
17 22.5 1.50 300 0.6 0.62 0.30 0.72 0.24 0.85 0.22
18 22.5 1.50 300 0.6 0.62 0.29 0.72 0.24 0.84 0.22
19 30 1.20 500 0.6 0.76 0.34 0.97 0.29 1.60 0.26
20 30 1.20 500 0.6 0.76 0.34 0.95 0.29 1.57 0.26
21 30 1.20 500 0.6 0.77 0.34 0.96 0.28 1.59 0.26
22 30 1.35 300 0.7 0.64 0.37 0.78 0.34 1.00 0.30
23 30 1.35 300 0.7 0.64 0.37 0.78 0.34 0.99 0.30
24 30 1.35 300 0.7 0.65 0.37 0.78 0.34 0.99 0.30
25 30 1.50 400 0.5 0.62 0.35 0.70 0.31 0.82 0.26
26 30 1.50 400 0.5 0.63 0.35 0.73 0.31 0.84 0.26
27 30 1.50 400 0.5 0.62 0.35 0.71 0.33 0.83 0.27

ECMM, electrochemical micromachining; MRR, material removal rate; OC, overcut.

By utilizing multi-attribute algorithms, scientists have established various decision-making statistical tools. The most common of them are ELECTRE [27], TOPSIS [28], GREY [29], and VIKOR [30]. TOPSIS, among them, holds its ground as it evaluates with minimal variation, has a lower computational complex and ensures that a common vertices plane is obtained, which postulates a close to ideal solution and negates the far from ideal solution [31]. The methodology of the decision-making in TOPSIS method is highlighted in Figure 4 [32].

Fig. 4

Methodology of TOPSIS (close to ideal solution).

The criteria of importance for factors under consideration is listed out by SIMO's weighting criteria method which is tabulated in Table 3. The valuation obtained using TOPSIS method, is listed out in Tables 46 for nonmagnetic and magnetic (Both attraction and repulsion) field ECMM conditions respectively.

Computational steps of SIMOS weighting procedure.

Subset criteria Number of criteria (variables) Number of position Non-normalized weighted matrix Total (%)
MRR 1 1 1/2*100 = 50~50 50
OC 1 2 11/2*100 =50~50 50

MRR, material removal rate; OC, overcut.

TOPSIS evaluation for ECMM of Ti-6Al-4V under nonmagnetic field.

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.36 18
2 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.37 16
3 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.36 17
4 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 3
5 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 1
6 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 2
7 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 10
8 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 12
9 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 11
10 22.5 1.20 400 0.7 0.08 0.12 0.06 0.00 0.03 25
11 22.5 1.20 400 0.7 0.08 0.12 0.07 0.00 0.00 27
12 22.5 1.20 400 0.7 0.08 0.12 0.06 0.00 0.01 26
13 22.5 1.35 500 0.5 0.10 0.09 0.04 0.04 0.50 8
14 22.5 1.35 500 0.5 0.10 0.09 0.04 0.03 0.50 9
15 22.5 1.35 500 0.5 0.10 0.09 0.03 0.04 0.51 7
16 22.5 1.50 300 0.6 0.08 0.08 0.05 0.04 0.43 15
17 22.5 1.50 300 0.6 0.09 0.08 0.05 0.04 0.43 14
18 22.5 1.50 300 0.6 0.09 0.08 0.05 0.04 0.44 13
19 30 1.20 500 0.6 0.10 0.09 0.03 0.03 0.52 4
20 30 1.20 500 0.6 0.10 0.09 0.03 0.03 0.51 5
21 30 1.20 500 0.6 0.10 0.10 0.03 0.03 0.51 6
22 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.24 24
23 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.25 23
24 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.26 22
25 30 1.50 400 0.5 0.08 0.10 0.05 0.02 0.31 21
26 30 1.50 400 0.5 0.09 0.10 0.05 0.02 0.32 19
27 30 1.50 400 0.5 0.09 0.10 0.05 0.02 0.31 20

ECMM, electrochemical micromachining.

TOPSIS evaluation for ECMM of Ti-6Al-4V under magnetic field (attraction).

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.07 0.08 0.09 0.05 0.34 16
2 15 1.20 300 0.5 0.07 0.08 0.09 0.04 0.34 17
3 15 1.20 300 0.5 0.07 0.08 0.09 0.04 0.33 18
4 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.82 1
5 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.80 3
6 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.82 2
7 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 10
8 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 11
9 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 12
10 22.5 1.20 400 0.7 0.07 0.13 0.10 0.00 0.03 26
11 22.5 1.20 400 0.7 0.07 0.13 0.10 0.00 0.03 27
12 22.5 1.20 400 0.7 0.07 0.12 0.10 0.00 0.03 25
13 22.5 1.35 500 0.5 0.10 0.09 0.06 0.05 0.43 8
14 22.5 1.35 500 0.5 0.09 0.09 0.07 0.05 0.41 9
15 22.5 1.35 500 0.5 0.10 0.08 0.06 0.05 0.44 6
16 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 14
17 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 15
18 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 13
19 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.45 5
20 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.44 7
21 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.46 4
22 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.21 22
23 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.21 23
24 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.22 21
25 30 1.50 400 0.5 0.08 0.10 0.09 0.03 0.25 20
26 30 1.50 400 0.5 0.08 0.10 0.08 0.03 0.26 19
27 30 1.50 400 0.5 0.08 0.10 0.09 0.02 0.20 24

ECMM, electrochemical micromachining.

TOPSIS evaluation for ECMM of Ti-6Al-4V under magnetic field (repulsion).

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.30 17
2 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.31 16
3 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.30 18
4 15 1.35 400 0.6 0.16 0.10 0.02 0.11 0.82 1
5 15 1.35 400 0.6 0.16 0.10 0.03 0.11 0.82 2
6 15 1.35 400 0.6 0.16 0.10 0.03 0.11 0.81 3
7 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.54 11
8 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.53 12
9 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.54 10
10 22.5 1.20 400 0.7 0.06 0.12 0.11 0.01 0.05 25
11 22.5 1.20 400 0.7 0.06 0.13 0.12 0.01 0.04 27
12 22.5 1.20 400 0.7 0.06 0.12 0.11 0.01 0.05 26
13 22.5 1.35 500 0.5 0.11 0.08 0.05 0.07 0.57 9
14 22.5 1.35 500 0.5 0.11 0.09 0.05 0.07 0.57 8
15 22.5 1.35 500 0.5 0.11 0.09 0.05 0.07 0.57 7
16 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 13
17 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 15
18 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 14
19 30 1.20 500 0.6 0.12 0.09 0.05 0.07 0.60 4
20 30 1.20 500 0.6 0.12 0.09 0.05 0.07 0.58 6
21 30 1.20 500 0.6 0.12 0.10 0.05 0.07 0.58 5
22 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.22 21
23 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.21 24
24 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.21 23
25 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.23 20
26 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.23 19
27 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.22 22

ECMM, electrochemical micromachining.

The experiments are done on samples under the parameters such as concentration of electrolyte 15 g/l, peak current 1.35 A, pulse on time 400 μs, and duty factor of 0.5 (close to ideal condition) at different conditions, to study the individual micro-structural properties and compare the effect of magnetic field when titanium alloy is electrochemically micro- machined. The machined samples are characterized by energy dispersive x-ray spectroscopy (EDS). Images (AFM) of the machined surface are probed, as the tip of the scan maneuvers alongside the z-axis, which has a spectrum of 2–110 μm, and apogee rate of 0.1 mm/s. The metallurgical changes and the residual stresses in the machined surface in different mediums is obtained using x-ray diffraction (XRD). The functional relevance of the machined surface is attributed by the integrity of the machined surface. The XRD technique is contemplated for the measurement of residual stress as well as to study its nature of stress (compressive or tensile) during the machining (boring) of surface by using copper anode (Cu_kα) [32].

Results and discussion
Effect of responses on factors under the influence of magnetic field

Based on Table 7 and Figure 5, we can say an improvement of 11.91–52.43% and 23.51–129.68% in MRR, 6.03–21.47% and 18.32–33.09% in OC is observed in electrochemical micromachining of titanium alloy under the influence of attraction and repulsion magnetic field, respectively, in correlation with nonmagnetic electro-chemical micromachining process.

Improvement in response factors in presence of magnetic field with respect to nonmagnetic field electrochemical micromachined Ti-6Al-4V.

% Increase in MRR % Decrease in OC
Concentration of electrolyte (g/l) Ip(A) Ton (μs) DF Attraction Repulsion Concentration of electrolyte (g/l) Ip(A) Ton (μs)
15 1.20 300 0.5 12.09 23.51 15 1.20 300
15 1.20 300 0.5 11.91 23.74 15 1.20 300
15 1.20 300 0.5 12.44 23.95 15 1.20 300
15 1.35 400 0.6 52.43 127.99 15 1.35 400
15 1.35 400 0.6 51.47 128.19 15 1.35 400
15 1.35 400 0.6 51.99 129.68 15 1.35 400
15 1.50 500 0.7 22.45 103.00 15 1.50 500
15 1.50 500 0.7 22.39 103.34 15 1.50 500
15 1.50 500 0.7 21.78 103.98 15 1.50 500
22.5 1.20 400 0.7 14.05 31.28 22.5 1.20 400
22.5 1.20 400 0.7 16.12 35.21 22.5 1.20 400
22.5 1.20 400 0.7 14.88 33.62 22.5 1.20 400
22.5 1.35 500 0.5 23.30 107.71 22.5 1.35 500
22.5 1.35 500 0.5 20.56 110.10 22.5 1.35 500
22.5 1.35 500 0.5 20.53 106.00 22.5 1.35 500
22.5 1.50 300 0.6 15.51 37.78 22.5 1.50 300
22.5 1.50 300 0.6 15.23 36.32 22.5 1.50 300
22.5 1.50 300 0.6 16.34 35.64 22.5 1.50 300
30 1.20 500 0.6 27.78 110.54 30 1.20 500
30 1.20 500 0.6 25.28 107.33 30 1.20 500
30 1.20 500 0.6 25.00 107.12 30 1.20 500
30 1.35 300 0.7 22.18 55.34 30 1.35 300
30 1.35 300 0.7 20.46 53.08 30 1.35 300
30 1.35 300 0.7 20.13 51.27 30 1.35 300
30 1.50 400 0.5 14.18 33.51 30 1.50 400
30 1.50 400 0.5 15.97 33.52 30 1.50 400
30 1.50 400 0.5 14.28 32.43 30 1.50 400

MRR, material removal rate; OC, overcut.

Fig. 5

Improvement in MRR and OC in presence of magnetic field when electrochemical micromachined Ti-6Al-4V. MRR, material removal rate; OC, overcut.

In a nonmagnetic field, the emergence of bubbles is observed and they accumulate around the hole like glomerule, and so the metal ions rotate near the reaction region leading to low mass transfer rate [23]. In attraction type of magnetic field, the bubbles will be exiting from the hole in one direction. In this condition, the current carrying conductor cuts the magnetic flux at 90° leading to the formation of Lorentz forces. The direction of Lorentz force is perpendicular to both magnetic field and the current which is outward from the reaction region. In repulsion magnetic field, the direction of ionic motion and the bubble movements are emerging out of the hole (in two directions) in a swirl motion. This is attributed to repulsive forces of magnets in the ECMM process. In this scenario, the current cuts the flux of two equal magnets with same poles causing the Lorentz's force in two directions. Apart from this, the repulsive force compresses the reaction region and causes the electrolyte to have a stirring or whirlpool effect. This causes the metal ion particles with the hydrogen bubbles to divide into two opposite directions which are perpendicular to both magnetic field and the current to move out of the reaction region. The improvement in ECMM MRR of titanium alloy is higher in the presence of magnetic field (attraction and repulsion) owing to MHD effect with the Lorentz force in correlation to nonmagnetic field. In both the conditions of attraction and repulsion magnetic fields, the direction of the Lorentz forces with MHD effect causes bubble movement causing a transfer of momentum from magnetic field driven ions in to the neighboring solute particles thereby enhancing the mass transfer rate [26].

This aids in the improvement in the amount of anodic dissolved-metal ions to flow in the direction out of the reaction region. In the case of nonmagnetic field, only the electric field plays the role of anodic dissolution, which does not match with the coupling effect of magnetic field ECMM process. With a controlled MHD effect, the OC is also reduced drastically as the metal ion particles move in the reverse direction in correlation to hydrogen bubbles and causing lower deviation and higher accuracy in the hole making operation [25].

Surface characterization analysis of electrochemical micromachined hole profile

Titanium alloys provide self-passivation ability which helps in the formation of titanium oxide layer, thus preventing the base material from dissolving [13]. The breakdown of the same would further result in dissolving and eroding the parent base metal properties [14]. EDS analysis, depicted in Figure 6, is carried out to study and characterize the machined layer in order to analyze the oxide layer breakdown effect [15]. The electrochemical micro- machined titanium alloys ideal solution for nonmagnetic field and magnetic field is taken in consideration around the hole profile to understand the base metal composition after the machining cycle [18]. For both the types of machining environments, no change is ascertained in the base metal, thereby concluding that there is negligible composition change during machining operation [16].

Fig. 6

EDS analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) without magnetic field and (B) with magnetic field. EDS, energy dispersive X-ray spectroscopy.

During the machining cycle in the absence of magnetic field, a precipitation is found near the hole edges. Sludges are formed as anodic dissolution persists in the electrolyte [16]. The liberated gas (hydrogen), gets accumulated around the hole profile causing higher erosion factor around the hole, as depicted in Figure 7(A), along the entry hole profile. This causes an effect on the accuracy of the hole profile, as the phenomenon of electrolyte gets altered in the presence of hydrogen bubbles around the region of metallic dissolution [17].

Fig. 7

Hole profile of electrochemical micromachined Ti-6Al-4V: (A) without and (B) with magnetic field.

More complex models need more convergence and accuracy. The accuracy can be achieved by utilizing a more precise tool design and good electrolyte reaction track. Precise tool design leads to economic costs associated with the machining operations. But, in the presence of magnetic field, it is possible to achieve the same. From Figure 8 and Table 8, surface roughness factor of the hole profile measured using atomic force microscope indicates a reduction of 55.34% in magnetic field ECMM in correlation with nonmagnetic field environment electrochemical machined titanium alloy. Also, from Figure 7, SEM images of entry diameter of the machined micro-holes indicate and support the reduction of burrs in the magnetic field electrochemical machining process. As explained earlier, for no magnetic field condition, the bubbles get accumulated around the hole, taking longer time to leave the hole entrance [18]. Also, they tend to merge and form larger bubbles leaving the electrolyte very little space to reach the tool tip [19].

Fig. 8

Atomic force microscopy of electrochemical micromachined Ti-6Al-4V hole profile: (A) without and (B) with magnetic field.

Topographical analysis of electrochemical micromachined Ti-6Al-4V hole profile.

ECMM environment Hole surface roughness (nm)
No magnetic field 159
Magnetic field 71

ECMM, electrochemical micromachining.

As for no circulation of electrolyte, the heat generation as well as the sludge formation at hole entrance becomes more aggressive. This would cause the reduction in OC values as well [20].

But, in the case of magnetic field electrochemical micromachining, the bubbles are leaving out in the direction of Lorentz force (one direction), taking the sludge away from the hole. In the cases of opposite poles, the bubbles leave out in two directions from the hole, as repulsive forces between magnets acts perpendicular to the electric field controlling the reaction region in a particular aspect resulting in a lesser OC.

The inner side wall circumvent of the machined hole, as indicated in Figures 7 and 8, is greatly influenced by the magnetic field assisted machining, because the inner wall feature is present for the purpose of adhesion, adsorption which controls the products to fix it inside the hole. A drop in surface roughness is also attributed to the magnetic field flux which is due to the repulsion forces, where a turbulence effect is created in the electrolyte causing a surge in the flow velocity and thus mobility of ions in the machining zone [21].

Electrochemical micromachining is considered to be a residual stress free machining process [22]. The residual stress (compressive) factor plays an important role in achieving the hardness of the surface after the machining cycle [27]. It is evaluated by using sin2Ψ technique [27]. From Table 9 and Figure 9, it is observed that there is an increase of 0.019% stress value in magnetic field assisted electrochemical micromachining of titanium alloy in correlation with nonmagnetic field ECMM [29]. A surge in the factor of stress would have indicated the presence of a residual factor, compressive or tensile. But from the pattern as indicated in Figure 9, two conditions no peak broadening or shift in the peaks is ascertained [28], which indicates minimal stress value. Thus, ECMM with the presence of magnetic field does not induce any outward stress on the component [32].

Residual stress analysis of electrochemical micromachined Ti-6Al-4V hole profile.

No magnetic field Magnetic field
Residual stress values (MPa) 259.62 264.89

Fig. 9

XRD analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) Without and (B) With magnetic field. XRD, x-ray diffraction.

This clearly indicates that no outward stress is affecting the machined material, even though environment of machining has been enhanced. A slight surge in the compressive residual factor will increase the passivation potential of titanium alloy, and would result in higher resistance to corrosion resistance [31], which is the inherent property of titanium alloy.

Conclusions

Influence of magnetic field on ECMM process is carried out for micro-hole machining of titanium alloy (Ti-6Al-4V) in correlation with nonmagnetic field ECMM process. The major attributes of the experimental investigation are:

A micro ECMM setup has been developed for carrying out the research, using sodium nitrite as electrolyte (owing to passive reaction on the surface). Neodymium magnets (Nd-Fe-B) are availed for magnetic field variation and measured using gauss meter.

Analysis indicates that the magnetic field in the electrochemical machining process plays a vital role in increasing the charge transfer rate by changing laminar flow of electrolyte into turbulent flow, thereby influencing the ionic and gas bubble movement and direction.

Close to ideal solution for magnetic and nonmagnetic field ECMM process is concentration electrolyte of 15 g/l, peak current of 1.35 A, pulse on time of 400 μs, and duty factor of 0.5.

An improvement of 11.91–52.43% and 23.51–129.68% in MRR, 6.03–21.47% and 18.32–33.09% in OC is observed in electrochemical micromachining of titanium alloy under the influence of attraction and repulsion magnetic field respectively in correlation with nonmagnetic field electrochemical micromachining process.

In a nonmagnetic field, the emergence of bubbles are accumulating around the hole like glomerule and the metal ions are rotating near the reaction region leading to less mass transfer rate, and only the presence of electric field leads to minimal anodic dissolution.

Surface roughness factor of the hole profile measured using atomic force microscope indicates a reduction of 55.34% in magnetic field ECMM in correlation with nonmagnetic field environment electrochemical machined titanium alloy.

During the machining cycle in the absence of magnetic field, a precipitation is observed near the hole edges. Sludges are formed as anodic dissolution persists in the electrolyte. The liberated gas (hydrogen) gets accumulated around the hole profile causing higher erosion factor around the hole.

Under repulsion magnetic field, the direction of ionic motion and the bubble movements are emerging out of the hole (in two directions) like a swirl motion. In this scenario, the current cuts the flux of two equal magnets with same poles causing the Lorentz's force in two directions. This repulsive force compresses the reaction region and causes the electrolyte to have a stirring or whirlpool effect. This makes the metal ion particles with the hydrogen bubbles to divide into two opposite directions which are perpendicular to both magnetic field and the current to move out of the reaction region, leading to higher MRR, lower OC, and better surface morphology.

No outward stress is affecting the machined material, even though environment of electrochemical machining process has been enhanced with the presence of magnetic field. A slight surge in the compressive residual factor helps in the increase of passivation potential of titanium alloy, and would result in higher resistance to outside environment changes, which is the inherent property of titanium alloy.

Fig. 1

Experimental setup for ECMM. ECMM, electrochemical micromachining.
Experimental setup for ECMM. ECMM, electrochemical micromachining.

Fig. 2

Magnetic field measurement of magnets using gauss meter.
Magnetic field measurement of magnets using gauss meter.

Fig. 3

Placement of magnets in the machining cycle.
Placement of magnets in the machining cycle.

Fig. 4

Methodology of TOPSIS (close to ideal solution).
Methodology of TOPSIS (close to ideal solution).

Fig. 5

Improvement in MRR and OC in presence of magnetic field when electrochemical micromachined Ti-6Al-4V. MRR, material removal rate; OC, overcut.
Improvement in MRR and OC in presence of magnetic field when electrochemical micromachined Ti-6Al-4V. MRR, material removal rate; OC, overcut.

Fig. 6

EDS analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) without magnetic field and (B) with magnetic field. EDS, energy dispersive X-ray spectroscopy.
EDS analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) without magnetic field and (B) with magnetic field. EDS, energy dispersive X-ray spectroscopy.

Fig. 7

Hole profile of electrochemical micromachined Ti-6Al-4V: (A) without and (B) with magnetic field.
Hole profile of electrochemical micromachined Ti-6Al-4V: (A) without and (B) with magnetic field.

Fig. 8

Atomic force microscopy of electrochemical micromachined Ti-6Al-4V hole profile: (A) without and (B) with magnetic field.
Atomic force microscopy of electrochemical micromachined Ti-6Al-4V hole profile: (A) without and (B) with magnetic field.

Fig. 9

XRD analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) Without and (B) With magnetic field. XRD, x-ray diffraction.
XRD analysis of electrochemical micromachined Ti-6Al-4V hole profile: (A) Without and (B) With magnetic field. XRD, x-ray diffraction.

Topographical analysis of electrochemical micromachined Ti-6Al-4V hole profile.

ECMM environment Hole surface roughness (nm)
No magnetic field 159
Magnetic field 71

Residual stress analysis of electrochemical micromachined Ti-6Al-4V hole profile.

No magnetic field Magnetic field
Residual stress values (MPa) 259.62 264.89

Experimental details of ECMM setup.

System working condition
Parameters Range
Working voltage 150 V DC
Gap voltage 0–10 V
Electrolyte NaNO3 + Water
Magnets Neodymium 40 × 20 × 10 mm
Tool Copper: ϕ 0.6 mm
Workpiece Ti-6Al-4V: 30 × 10 × 0.1 mm

TOPSIS evaluation for ECMM of Ti-6Al-4V under nonmagnetic field.

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.36 18
2 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.37 16
3 15 1.20 300 0.5 0.08 0.09 0.05 0.03 0.36 17
4 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 3
5 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 1
6 15 1.35 400 0.6 0.13 0.10 0.02 0.06 0.78 2
7 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 10
8 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 12
9 15 1.50 500 0.7 0.10 0.09 0.04 0.03 0.48 11
10 22.5 1.20 400 0.7 0.08 0.12 0.06 0.00 0.03 25
11 22.5 1.20 400 0.7 0.08 0.12 0.07 0.00 0.00 27
12 22.5 1.20 400 0.7 0.08 0.12 0.06 0.00 0.01 26
13 22.5 1.35 500 0.5 0.10 0.09 0.04 0.04 0.50 8
14 22.5 1.35 500 0.5 0.10 0.09 0.04 0.03 0.50 9
15 22.5 1.35 500 0.5 0.10 0.09 0.03 0.04 0.51 7
16 22.5 1.50 300 0.6 0.08 0.08 0.05 0.04 0.43 15
17 22.5 1.50 300 0.6 0.09 0.08 0.05 0.04 0.43 14
18 22.5 1.50 300 0.6 0.09 0.08 0.05 0.04 0.44 13
19 30 1.20 500 0.6 0.10 0.09 0.03 0.03 0.52 4
20 30 1.20 500 0.6 0.10 0.09 0.03 0.03 0.51 5
21 30 1.20 500 0.6 0.10 0.10 0.03 0.03 0.51 6
22 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.24 24
23 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.25 23
24 30 1.35 300 0.7 0.09 0.10 0.05 0.02 0.26 22
25 30 1.50 400 0.5 0.08 0.10 0.05 0.02 0.31 21
26 30 1.50 400 0.5 0.09 0.10 0.05 0.02 0.32 19
27 30 1.50 400 0.5 0.09 0.10 0.05 0.02 0.31 20

TOPSIS evaluation for ECMM of Ti-6Al-4V under magnetic field (repulsion).

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.30 17
2 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.31 16
3 15 1.20 300 0.5 0.05 0.08 0.11 0.05 0.30 18
4 15 1.35 400 0.6 0.16 0.10 0.02 0.11 0.82 1
5 15 1.35 400 0.6 0.16 0.10 0.03 0.11 0.82 2
6 15 1.35 400 0.6 0.16 0.10 0.03 0.11 0.81 3
7 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.54 11
8 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.53 12
9 15 1.50 500 0.7 0.11 0.09 0.06 0.07 0.54 10
10 22.5 1.20 400 0.7 0.06 0.12 0.11 0.01 0.05 25
11 22.5 1.20 400 0.7 0.06 0.13 0.12 0.01 0.04 27
12 22.5 1.20 400 0.7 0.06 0.12 0.11 0.01 0.05 26
13 22.5 1.35 500 0.5 0.11 0.08 0.05 0.07 0.57 9
14 22.5 1.35 500 0.5 0.11 0.09 0.05 0.07 0.57 8
15 22.5 1.35 500 0.5 0.11 0.09 0.05 0.07 0.57 7
16 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 13
17 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 15
18 22.5 1.50 300 0.6 0.06 0.08 0.10 0.05 0.32 14
19 30 1.20 500 0.6 0.12 0.09 0.05 0.07 0.60 4
20 30 1.20 500 0.6 0.12 0.09 0.05 0.07 0.58 6
21 30 1.20 500 0.6 0.12 0.10 0.05 0.07 0.58 5
22 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.22 21
23 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.21 24
24 30 1.35 300 0.7 0.07 0.11 0.10 0.03 0.21 23
25 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.23 20
26 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.23 19
27 30 1.50 400 0.5 0.06 0.10 0.10 0.03 0.22 22

TOPSIS evaluation for ECMM of Ti-6Al-4V under magnetic field (attraction).

S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF Weighted matrix Distance from ideal solution Closeness coefficient Rank
WMRR WOC Eij+ Eij CCij
1 15 1.20 300 0.5 0.07 0.08 0.09 0.05 0.34 16
2 15 1.20 300 0.5 0.07 0.08 0.09 0.04 0.34 17
3 15 1.20 300 0.5 0.07 0.08 0.09 0.04 0.33 18
4 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.82 1
5 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.80 3
6 15 1.35 400 0.6 0.16 0.10 0.02 0.09 0.82 2
7 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 10
8 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 11
9 15 1.50 500 0.7 0.09 0.09 0.07 0.04 0.40 12
10 22.5 1.20 400 0.7 0.07 0.13 0.10 0.00 0.03 26
11 22.5 1.20 400 0.7 0.07 0.13 0.10 0.00 0.03 27
12 22.5 1.20 400 0.7 0.07 0.12 0.10 0.00 0.03 25
13 22.5 1.35 500 0.5 0.10 0.09 0.06 0.05 0.43 8
14 22.5 1.35 500 0.5 0.09 0.09 0.07 0.05 0.41 9
15 22.5 1.35 500 0.5 0.10 0.08 0.06 0.05 0.44 6
16 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 14
17 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 15
18 22.5 1.50 300 0.6 0.08 0.08 0.08 0.05 0.37 13
19 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.45 5
20 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.44 7
21 30 1.20 500 0.6 0.10 0.09 0.06 0.05 0.46 4
22 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.21 22
23 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.21 23
24 30 1.35 300 0.7 0.08 0.11 0.08 0.02 0.22 21
25 30 1.50 400 0.5 0.08 0.10 0.09 0.03 0.25 20
26 30 1.50 400 0.5 0.08 0.10 0.08 0.03 0.26 19
27 30 1.50 400 0.5 0.08 0.10 0.09 0.02 0.20 24

Computational steps of SIMOS weighting procedure.

Subset criteria Number of criteria (variables) Number of position Non-normalized weighted matrix Total (%)
MRR 1 1 1/2*100 = 50~50 50
OC 1 2 11/2*100 =50~50 50

Orthogonal array experiment (L27) for magnetic and nonmagnetic field ECMM of Ti-6Al-4V titanium alloy.

No magnetic force Attraction magnetic force Repulsion magnetic force
S. No. Concentration of electrolyte (g/l) Ip (A) Ton (μs) DF MRR 10−3 (mm3/min) OC (mm) MRR 10−3 (mm3/min) OC (mm) MRR 10−3 (mm3/min) OC (mm)
1 15 1.20 300 0.5 0.59 0.32 0.66 0.25 0.72 0.21
2 15 1.20 300 0.5 0.59 0.32 0.66 0.25 0.73 0.21
3 15 1.20 300 0.5 0.59 0.32 0.66 0.26 0.73 0.22
4 15 1.35 400 0.6 0.97 0.35 1.48 0.31 2.22 0.28
5 15 1.35 400 0.6 0.97 0.35 1.47 0.31 2.22 0.28
6 15 1.35 400 0.6 0.96 0.35 1.47 0.31 2.21 0.28
7 15 1.50 500 0.7 0.72 0.33 0.88 0.28 1.46 0.24
8 15 1.50 500 0.7 0.72 0.33 0.88 0.28 1.46 0.24
9 15 1.50 500 0.7 0.72 0.33 0.87 0.28 1.47 0.24
10 22.5 1.20 400 0.7 0.60 0.43 0.68 0.39 0.78 0.34
11 22.5 1.20 400 0.7 0.59 0.43 0.68 0.39 0.79 0.35
12 22.5 1.20 400 0.7 0.59 0.43 0.68 0.39 0.79 0.34
13 22.5 1.35 500 0.5 0.72 0.32 0.89 0.27 1.50 0.23
14 22.5 1.35 500 0.5 0.73 0.32 0.87 0.27 1.52 0.24
15 22.5 1.35 500 0.5 0.73 0.32 0.89 0.26 1.51 0.23
16 22.5 1.50 300 0.6 0.62 0.30 0.72 0.24 0.85 0.22
17 22.5 1.50 300 0.6 0.62 0.30 0.72 0.24 0.85 0.22
18 22.5 1.50 300 0.6 0.62 0.29 0.72 0.24 0.84 0.22
19 30 1.20 500 0.6 0.76 0.34 0.97 0.29 1.60 0.26
20 30 1.20 500 0.6 0.76 0.34 0.95 0.29 1.57 0.26
21 30 1.20 500 0.6 0.77 0.34 0.96 0.28 1.59 0.26
22 30 1.35 300 0.7 0.64 0.37 0.78 0.34 1.00 0.30
23 30 1.35 300 0.7 0.64 0.37 0.78 0.34 0.99 0.30
24 30 1.35 300 0.7 0.65 0.37 0.78 0.34 0.99 0.30
25 30 1.50 400 0.5 0.62 0.35 0.70 0.31 0.82 0.26
26 30 1.50 400 0.5 0.63 0.35 0.73 0.31 0.84 0.26
27 30 1.50 400 0.5 0.62 0.35 0.71 0.33 0.83 0.27

Improvement in response factors in presence of magnetic field with respect to nonmagnetic field electrochemical micromachined Ti-6Al-4V.

% Increase in MRR % Decrease in OC
Concentration of electrolyte (g/l) Ip(A) Ton (μs) DF Attraction Repulsion Concentration of electrolyte (g/l) Ip(A) Ton (μs)
15 1.20 300 0.5 12.09 23.51 15 1.20 300
15 1.20 300 0.5 11.91 23.74 15 1.20 300
15 1.20 300 0.5 12.44 23.95 15 1.20 300
15 1.35 400 0.6 52.43 127.99 15 1.35 400
15 1.35 400 0.6 51.47 128.19 15 1.35 400
15 1.35 400 0.6 51.99 129.68 15 1.35 400
15 1.50 500 0.7 22.45 103.00 15 1.50 500
15 1.50 500 0.7 22.39 103.34 15 1.50 500
15 1.50 500 0.7 21.78 103.98 15 1.50 500
22.5 1.20 400 0.7 14.05 31.28 22.5 1.20 400
22.5 1.20 400 0.7 16.12 35.21 22.5 1.20 400
22.5 1.20 400 0.7 14.88 33.62 22.5 1.20 400
22.5 1.35 500 0.5 23.30 107.71 22.5 1.35 500
22.5 1.35 500 0.5 20.56 110.10 22.5 1.35 500
22.5 1.35 500 0.5 20.53 106.00 22.5 1.35 500
22.5 1.50 300 0.6 15.51 37.78 22.5 1.50 300
22.5 1.50 300 0.6 15.23 36.32 22.5 1.50 300
22.5 1.50 300 0.6 16.34 35.64 22.5 1.50 300
30 1.20 500 0.6 27.78 110.54 30 1.20 500
30 1.20 500 0.6 25.28 107.33 30 1.20 500
30 1.20 500 0.6 25.00 107.12 30 1.20 500
30 1.35 300 0.7 22.18 55.34 30 1.35 300
30 1.35 300 0.7 20.46 53.08 30 1.35 300
30 1.35 300 0.7 20.13 51.27 30 1.35 300
30 1.50 400 0.5 14.18 33.51 30 1.50 400
30 1.50 400 0.5 15.97 33.52 30 1.50 400
30 1.50 400 0.5 14.28 32.43 30 1.50 400

Sorkhel SK, Bhattacharyya B. Parametric control for optimal quality of the workpiece surface in ECM. J Mater Process Technol. 1994;40(3–4):271–86. SorkhelSK BhattacharyyaB Parametric control for optimal quality of the workpiece surface in ECM J Mater Process Technol 1994 40 3–4 271 86 Search in Google Scholar

Borchers F, Clausen B, Eckert S, Ehle L, Epp J, Harst S, et al. Comparison of different manufacturing processes of AISI 4140 steel with regard to surface modification and its influencing depth. Metals. 2020;10(7):895. BorchersF ClausenB EckertS EhleL EppJ HarstS Comparison of different manufacturing processes of AISI 4140 steel with regard to surface modification and its influencing depth Metals 2020 10 7 895 Search in Google Scholar

Sen M, Shan HS. A review of electrochemical macro-to micro-hole drilling processes. Int J Mach Tools Manuf. 2005;45(2):137–52. SenM ShanHS A review of electrochemical macro-to micro-hole drilling processes Int J Mach Tools Manuf 2005 45 2 137 52 Search in Google Scholar

Rosenkranz C, Lohrengel MM, Schultze JW. The surface structure during pulsed ECM of iron in NaNO3. Electrochim Acta. 2005;50(10):2009–16. RosenkranzC LohrengelMM SchultzeJW The surface structure during pulsed ECM of iron in NaNO3 Electrochim Acta 2005 50 10 2009 16 Search in Google Scholar

De Silva AKM, Altena HSJ, McGeough JA. Precision ECM by process characteristic modelling. CIRP Annals. 2000;49(1):151–5. De SilvaAKM AltenaHSJ McGeoughJA Precision ECM by process characteristic modelling CIRP Annals 2000 49 1 151 5 Search in Google Scholar

El-Hofy H. Vibration-assisted electrochemical machining: a review. Int J Adv Manuf Technol. 2019;105(1–4):579–93. El-HofyH Vibration-assisted electrochemical machining: a review Int J Adv Manuf Technol 2019 105 1–4 579 93 Search in Google Scholar

Shin HS, Kim BH, Chu CN. Analysis of the side gap resulting from micro electrochemical machining with a tungsten wire and ultrashort voltage pulses. J Micromech Microeng. 2008;18(7):075009. ShinHS KimBH ChuCN Analysis of the side gap resulting from micro electrochemical machining with a tungsten wire and ultrashort voltage pulses J Micromech Microeng 2008 18 7 075009 Search in Google Scholar

Eylon DSPJ, Fujishiro S, Postans PJ, Froes FH. High-temperature titanium alloys – a review. JOM. 1984;36(11):55–62. EylonDSPJ FujishiroS PostansPJ FroesFH High-temperature titanium alloys – a review JOM 1984 36 11 55 62 Search in Google Scholar

Bhattacharyya B, Munda J, Malapati M. Advancement in electrochemical micro-machining. Int J Mach Tools Manuf. 2004;44(15):1577–89. BhattacharyyaB MundaJ MalapatiM Advancement in electrochemical micro-machining Int J Mach Tools Manuf 2004 44 15 1577 89 Search in Google Scholar

Patel DS, Sharma V, Jain VK, Ramkumar J. Reducing overcut in electrochemical micromachining process by altering the energy of voltage pulse using sinusoidal and triangular waveform. Int J Mach Tools Manuf. 2020;151:103526. PatelDS SharmaV JainVK RamkumarJ Reducing overcut in electrochemical micromachining process by altering the energy of voltage pulse using sinusoidal and triangular waveform Int J Mach Tools Manuf 2020 151 103526 Search in Google Scholar

Malik A, Manna A. Investigation on the laser-assisted jet electrochemical machining process for improvement in machining performance. Int J Adv Manuf Technol. 2018;96(9):3917–32. MalikA MannaA Investigation on the laser-assisted jet electrochemical machining process for improvement in machining performance Int J Adv Manuf Technol 2018 96 9 3917 32 Search in Google Scholar

Zhang Z, Zhang Y, Ming W, Zhang Y, Cao C, Zhang G. A review on magnetic field assisted electrical discharge machining. J Manuf Process. 2021;64:694–722. ZhangZ ZhangY MingW ZhangY CaoC ZhangG A review on magnetic field assisted electrical discharge machining J Manuf Process 2021 64 694 722 Search in Google Scholar

Wang Z, Sun L, Ke W, Zeng Z, Yao W, Wang C. Laser oscillating welding of TC31 high-temperature titanium alloy. Metals. 2020;10(9):1185. WangZ SunL KeW ZengZ YaoW WangC Laser oscillating welding of TC31 high-temperature titanium alloy Metals 2020 10 9 1185 Search in Google Scholar

Oke SR, Ogunwande GS, Onifade M, Aikulola E, Adewale ED, Olawale OE, et al. An overview of conventional and non-conventional techniques for machining of titanium alloys. Manuf Rev. 2020;7:34. OkeSR OgunwandeGS OnifadeM AikulolaE AdewaleED OlawaleOE An overview of conventional and non-conventional techniques for machining of titanium alloys Manuf Rev 2020 7 34 Search in Google Scholar

Zhang X, Zhang J, Chen F, Yang Z, He J. Characteristics of resistance spot welded Ti6Al4V titanium alloy sheets. Metals. 2017;7(10):424. ZhangX ZhangJ ChenF YangZ HeJ Characteristics of resistance spot welded Ti6Al4V titanium alloy sheets Metals 2017 7 10 424 Search in Google Scholar

Pradeep N, Sundaram KS, Pradeep Kumar M. Performance investigation of variant polymer graphite electrodes used in electrochemical micromachining of ASTM A240 grade 304. Mater Manuf Process. 2020;35(1):72–85. PradeepN SundaramKS Pradeep KumarM Performance investigation of variant polymer graphite electrodes used in electrochemical micromachining of ASTM A240 grade 304 Mater Manuf Process 2020 35 1 72 85 Search in Google Scholar

Mouliprasanth B, Hariharan P. Measurement of performance and geometrical features in electrochemical micromachining of SS304 alloy. Exp Tech. 2020;44:259–73. MouliprasanthB HariharanP Measurement of performance and geometrical features in electrochemical micromachining of SS304 alloy Exp Tech 2020 44 259 73 Search in Google Scholar

Hariharan K, Chandrasekhara Sastry C, Padmanaban M, Gideon Ganesh M. Experimental investigation of bio-ceramic (Hydroxyapatite and Yttrium stabilized zirconia) composite on Ti6Al7Nb alloy for medical implants. Mater Manuf Process. 2020;35(1):521–530. HariharanK Chandrasekhara SastryC PadmanabanM Gideon GaneshM Experimental investigation of bio-ceramic (Hydroxyapatite and Yttrium stabilized zirconia) composite on Ti6Al7Nb alloy for medical implants Mater Manuf Process 2020 35 1 521 530 Search in Google Scholar

Rønold HJ, Ellingsen JE. Effect of micro-roughness produced by TiO2 blasting–tensile testing of bone attachment by using coin-shaped implants. Biomaterials. 2002;23(21):4211–9. RønoldHJ EllingsenJE Effect of micro-roughness produced by TiO2 blasting–tensile testing of bone attachment by using coin-shaped implants Biomaterials 2002 23 21 4211 9 Search in Google Scholar

Dhobe SD, Doloi B, Bhattacharyya B. Surface characteristics of ECMed titanium work samples for biomedical applications. Int J Adv Manuf Technol. 2011;55(1–4):177–88. DhobeSD DoloiB BhattacharyyaB Surface characteristics of ECMed titanium work samples for biomedical applications Int J Adv Manuf Technol 2011 55 1–4 177 88 Search in Google Scholar

Lu X, Leng Y. Electrochemical micromachining of titanium surfaces for biomedical applications. J Mater Process Technol. 2005;169(2):173–8. LuX LengY Electrochemical micromachining of titanium surfaces for biomedical applications J Mater Process Technol 2005 169 2 173 8 Search in Google Scholar

Altena HS. EDM and ECM for mass production Philips DAP. J Mater Process Technol. 2004;149(1–3):18–21. AltenaHS EDM and ECM for mass production Philips DAP J Mater Process Technol 2004 149 1–3 18 21 Search in Google Scholar

Hinds G, Spada FE, Coey JMD, Ní Mhíocháin TR, Lyons MEG. Magnetic field effects on copper electrolysis. J Phys Chem B. 2001;105(39):9487–502. HindsG SpadaFE CoeyJMD Ní MhíocháinTR LyonsMEG Magnetic field effects on copper electrolysis J Phys Chem B 2001 105 39 9487 502 Search in Google Scholar

Fahidy TZ. Magnetoelectrolysis. J Appl Electrochem. 1983;13(5):553–63. FahidyTZ Magnetoelectrolysis J Appl Electrochem 1983 13 5 553 63 Search in Google Scholar

Mohanta S, Fahidy TZ. The hydrodynamics of a magnetoelectrolytic cell. J Appl Electrochem. 1976;6(3):211–20. MohantaS FahidyTZ The hydrodynamics of a magnetoelectrolytic cell J Appl Electrochem 1976 6 3 211 20 Search in Google Scholar

Long L, Baoji MA. Effect of magnetic field on anodic dissolution in electrochemical machining. Int J Adv Manuf Technol. 2018;94(1–4):1177–1187. LongL BaojiMA Effect of magnetic field on anodic dissolution in electrochemical machining Int J Adv Manuf Technol 2018 94 1–4 1177 1187 Search in Google Scholar

Chandrasekhara Sastry C, Hariharan P, Pradeep Kumar M. Experimental investigation of dry, wet and cryogenic boring of AA 7075 alloy. Mater Manuf Process. 2019;34(7):814–831. Chandrasekhara SastryC HariharanP Pradeep KumarM Experimental investigation of dry, wet and cryogenic boring of AA 7075 alloy Mater Manuf Process 2019 34 7 814 831 Search in Google Scholar

Chandrasekhara Sastry C, Hariharan P, Pradeep Kumar M, Muthu Manickam MA. Experimental investigation on boring of HSLA ASTM A36 steel under dry, wet and cryogenic boring environments. Mater Manuf Process. 2019;34(12):1352–79. Chandrasekhara SastryC HariharanP Pradeep KumarM Muthu ManickamMA Experimental investigation on boring of HSLA ASTM A36 steel under dry, wet and cryogenic boring environments Mater Manuf Process 2019 34 12 1352 79 Search in Google Scholar

Goutham Murari VP, Selvakumar G, Chandrasekhara CS. Experimental investigation of wire-EDM machining of low conductive Al-SiC-TiC metal matrix composite. Metals. 2020;10(9):1188. Goutham MurariVP SelvakumarG ChandrasekharaCS Experimental investigation of wire-EDM machining of low conductive Al-SiC-TiC metal matrix composite Metals 2020 10 9 1188 Search in Google Scholar

Chandrasekhara Sastry C, Gokulakrishnan K, Hariharan P, Pradeep Kumar M, Boopathy SR. Investigation of boring on gunmetal in dry, wet and cryogenic conditions. J Braz Soc Mech Sci Eng. 2020;42(1):16. Chandrasekhara SastryC GokulakrishnanK HariharanP Pradeep KumarM BoopathySR Investigation of boring on gunmetal in dry, wet and cryogenic conditions J Braz Soc Mech Sci Eng 2020 42 1 16 Search in Google Scholar

Rajamanickam S, Prasanna J, Chandrasekhara Sastry C. Analysis of high aspect ratio small holes in rapid electrical discharge machining of superalloys using Taguchi and TOPSIS. J Braz Soc Mech Sci Eng. 2020;42(2):99. RajamanickamS PrasannaJ Chandrasekhara SastryC Analysis of high aspect ratio small holes in rapid electrical discharge machining of superalloys using Taguchi and TOPSIS J Braz Soc Mech Sci Eng 2020 42 2 99 Search in Google Scholar

Chandrasekhara Sastry C, Abeens M, Pradeep N, Muthu Manickam MA. Microstructural analysis, radiography, tool wear characterization, induced residual stress and corrosion behavior of conventional and cryogenic trepanning of DSS 2507. J Mech Sci Technol. 2020;34:2535–47. Chandrasekhara SastryC AbeensM PradeepN Muthu ManickamMA Microstructural analysis, radiography, tool wear characterization, induced residual stress and corrosion behavior of conventional and cryogenic trepanning of DSS 2507 J Mech Sci Technol 2020 34 2535 47 Search in Google Scholar

Qu N, Fang X, Li W, Zeng Y, Zhu D. Wire electrochemical machining with axial electrolyte flushing for titanium alloy. Chinese J Aeronaut. 2013;26(1):224–9. QuN FangX LiW ZengY ZhuD Wire electrochemical machining with axial electrolyte flushing for titanium alloy Chinese J Aeronaut 2013 26 1 224 9 Search in Google Scholar

Xu B, Wu XY, Lei JG, Liang X, Zhao H, Guo DJ, Ruan SC. Micro-ECM of 3D micro-electrode for efficiently processing 3D micro-structure. Int J Adv Manuf Tech. 2017;91(1):709–717. XuB WuXY LeiJG LiangX ZhaoH GuoDJ RuanSC Micro-ECM of 3D micro-electrode for efficiently processing 3D micro-structure Int J Adv Manuf Tech 2017 91 1 709 717 Search in Google Scholar

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