# Experimental Research on Machining Localization and Surface Quality in Micro Electrochemical Milling of Nickel-Based Superalloy

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## Abstract

**:**

## 1. Introduction

## 2. Principle of Micro Electrochemical Milling

_{on}is pulse on time, t

_{off}is pulse interval, Φ

_{b}is decomposition potential of anode, C

_{d}is capacitance of the electric double layer, R

_{f}is resistance of electrochemical reaction, and R

_{e}is resistance of electrolyte.

## 3. Experimental System and Arrangement

## 4. Experimental Results and Analysis

#### 4.1. Influence of Applied Voltage on Machining Localization and Surface Roughness

_{2}SO

_{4}electrolyte, workpiece of a nickel-base superalloy (GH3030) plate with the thickness of 300 μm, pulse period of 1 µs, pulse on time of 95 ns, electrode diameter of 10 μm, feed rate of 0.2 μm/s, and depth of 10 μm. Figure 5 shows the variation of the side gap and surface roughness with an applied voltage on 3.5 V, 4 V, 4.5 V, and 5 V.

#### 4.2. Influence of Pulse on Time on Machining Localization and Surface Roughness

#### 4.3. Influence of Pulse Period on Machining Localization and Surface Roughness

#### 4.4. Influence of Electrolyte Concentration on Machining Localization and Surface Roughness

_{2}SO

_{4}electrolyte is generally 0.2 mol/L under the premise of ensuring stable machining and certain machining efficiency.

#### 4.5. Influence of Electrode Diameter on Machining Localization

#### 4.6. Machining of 2D and 3D Complex Structures

_{2}SO

_{4}electrolyte, workpiece of a nickel-base superalloy (GH3030) plate with the thickness of 300 μm, pulse period of 1 µs, pulse on time of 95 ns, electrode diameter of 10 μm, feed rate of 0.2 μm /s, and applied voltage of 4.5 V. Figure 15b shows a heart-shaped structure with the width of 25 µm and the depth of 20 µm, and the parameters are the same as Figure 15a.

## 5. Conclusions

- Based on the transient reaction process of the electrochemical double layer, the mathematical model of micro electrochemical milling was established, which lays a theoretical foundation for the subsequent experiments. That is: when the feed rate is constant, the electrode feed depth ${L}_{c}$ along the Z-axis cannot be greater than the electrode diameter $d$ to ensure better shape and dimensional precision.
- The high precision micro-electrochemical machining platform was set up. Several experiments were carried out and the influence of applied voltage, pulse on time, pulse period, electrolyte concentration and electrode diameter on machining localization and surface roughness was analyzed. The side gap increases with the increase of applied voltage, pulse on time, electrolyte concentration, and the electrode diameter, and decreases with the increase of the pulse period. Then, the optimized parameters were obtained, which combined the effects of the surface roughness.
- Based on the optimization of the above parameters, the 2D complex shapes and the 3D square cavity structures were successfully machined, which have good shape precision and good surface quality. It is proved that the micro electrochemical milling with nanosecond pulse is an effective method that can meet the machining requirements of micro devices.

## Author Contributions

## Funding

## Conflicts of Interest

## References

- McGenough, J.A.; Leu, M.C.; Rajurkar, K.P.; DeSilva, A.K.M.; Liu, Q. Electroforming process and application to micro/macro manufacturing. CIRP Ann.
**2001**, 50, 499–514. [Google Scholar] [CrossRef] - Rajurkar, K.P.; Levy, G.; Malshe, A.; Sundaram, M.M.; McGeough, J.; Hu, X.; Resnick, R.; DeSilva, A. Micro and nanomachining by electro physical and chemical processes. CIRP Ann.
**2006**, 55, 643–666. [Google Scholar] [CrossRef] - Nasim, S.; Mohammad, R.R.; Mansour, H. Experimental investigation of surfactant-mixed electrolyte into electro chemical discharge machining (ECDM) process. J. Mater. Process. Technol.
**2017**, 250, 190–202. [Google Scholar] - Zhang, Z.Y.; Huang, L.; Jiang, Y.J.; Liu, G.; Nie, X.; Lu, H.; Zhuang, H. A study to explore the properties of electrochemical discharge effect based on pulse power supply. Int. J. Adv. Manuf. Technol.
**2016**, 85, 2107–2114. [Google Scholar] [CrossRef] - Wang, M.; Zhang, J.; Liu, Y.; Li, M. Investigation of micro electrochemical discharge machining tool with high efficiency. Recent Pat. Eng.
**2016**, 10, 146–153. [Google Scholar] [CrossRef] - Bhattacharyya, B.; Munda, J.; Malapati, M. Advancement in electrochemical micro-machining. Int. J. Mach. Tools Manuf.
**2004**, 44, 1577–1589. [Google Scholar] [CrossRef] - Schuster, R.; Kirchner, V.; Allongue, P.; Ertl, G. Electrochemical micromachining. Science
**2000**, 289, 98–101. [Google Scholar] [CrossRef] [PubMed] - Kunar, S.; Bhattacharyya, B. Investigation on surface structuring generated by electrochemical micromachining. Adv. Manuf.
**2017**, 5, 217–230. [Google Scholar] [CrossRef] - Rathod, V.; Doloi, B.; Bhattacharyya, B. Fabrication of microgrooves with varied cross-sections by electrochemical micromachining. Int. J. Adv. Manuf. Technol.
**2017**, 92, 505–518. [Google Scholar] [CrossRef] - Rathod, V.; Doloi, B.; Bhattacharyya, B. Influence of electrochemical micromachining parameters during generation of microgrooves. Int. J. Adv. Manuf. Technol.
**2015**, 76, 51–60. [Google Scholar] [CrossRef] - Rathod, V.; Doloi, B.; Bhattacharyya, B. Experimental investigations into machining accuracy and surface roughness of microgrooves fabricated by electrochemical micromachining. Inst. Mech. Eng.
**2014**, 229, 1781–1802. [Google Scholar] [CrossRef] - Yuan, Y.; Han, L.; Huang, D.; Su, J.; Tian, Z.; Tian, Z.W.; Zhan, D. Electrochemical micromachining under mechanical motion mode. Electrochim. Acta
**2015**, 183, 3–7. [Google Scholar] [CrossRef] - Xu, L.Z.; Zhao, C.Y. Nanometer-scale accuracy electrochemical micromachining with adjustable inductance. Electrochim. Acta
**2017**, 248, 75–78. [Google Scholar] [CrossRef] - Meng, L.C.; Zeng, Y.B.; Fang, X.L.; Zhu, D. Micropatterning of Ni-based metallic glass by pulsed wire electrochemical micro machining. Intermetallics
**2017**, 81, 16–25. [Google Scholar] [CrossRef] - Meng, L.C.; Zeng, Y.B.; Zhu, D. Investigation on wire electrochemical micromachining of Ni-based metallic glass. Electrochim. Acta
**2017**, 233, 274–283. [Google Scholar] [CrossRef] - Cole, K.M.; Kirk, D.W.; Singh, C.V.; Thorpe, S.J. Optimizing electrochemical micromachining parameters for Zr-based bulk metallic glass. J. Manuf. Process.
**2017**, 25, 227–234. [Google Scholar] [CrossRef] - Trimmer, A.L.; Hudson, J.L.; Kock, M.; Schuster, R. Single-step electrochemical machining of complex nanostructures with ultrashort voltage pulses. Appl. Phys. Lett.
**2003**, 82, 3327–3329. [Google Scholar] [CrossRef] - Lee, E.S.; Baek, S.Y.; Cho, C.R. A study of the characteristics for electrochemical micromachining with ultrashort voltage pulses. Int. J. Adv. Manuf. Tehnol.
**2005**, 31, 762–769. [Google Scholar] [CrossRef]

**Figure 6.**The microgroove under different voltages. (

**a**) The SEM image of the microgroove; (

**b**) The appearance of the microgroove.

**Figure 8.**The microgroove under different pulse on times. (

**a**) The SEM image of the microgroove; (

**b**) The appearance of the microgroove.

**Figure 10.**The microgroove under different pulse periods. (

**a**) The SEM image of the microgroove; (

**b**) The appearance of the microgroove.

**Figure 12.**The microgroove under different electrolyte concentrations. (

**a**) The SEM images of the microgroove; (

**b**) The appearance of the microgroove.

**Figure 14.**The SEM images of the microgroove under different electrode diameters. (

**a**) 4 µm; (

**b**) 7 µm; (

**c**) 10 µm; (

**d**) 18 µm.

**Figure 16.**A 3D complex micro-structure. (

**a**) A square cavity structure; (

**b**) The cross section surface morphology.

Machining Conditions | Parameter |
---|---|

Applied Voltage (V) | 3.5–5.5 |

Pulse on Time (ns) | 60–150 |

Pulse Period (μs) | 1 |

Electrode Diameter (μm) | 3–20 |

Workpiece Material | Super alloy (GH3030) |

Electrolyte | 0.2M H_{2}SO_{4} solution |

Mill Layer Thickness (μm) | $\le $electrode diameter |

Feed Rate (μm/s) | 0.2–1 |

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**MDPI and ACS Style**

Liu, Y.; Jiang, Y.; Guo, C.; Deng, S.; Kong, H.
Experimental Research on Machining Localization and Surface Quality in Micro Electrochemical Milling of Nickel-Based Superalloy. *Micromachines* **2018**, *9*, 402.
https://doi.org/10.3390/mi9080402

**AMA Style**

Liu Y, Jiang Y, Guo C, Deng S, Kong H.
Experimental Research on Machining Localization and Surface Quality in Micro Electrochemical Milling of Nickel-Based Superalloy. *Micromachines*. 2018; 9(8):402.
https://doi.org/10.3390/mi9080402

**Chicago/Turabian Style**

Liu, Yong, Yong Jiang, Chunsheng Guo, Shihui Deng, and Huanghai Kong.
2018. "Experimental Research on Machining Localization and Surface Quality in Micro Electrochemical Milling of Nickel-Based Superalloy" *Micromachines* 9, no. 8: 402.
https://doi.org/10.3390/mi9080402