0
Research Papers

Effect of Dielectric Electrical Conductivity on the Characteristics of Micro Electro-Discharge Machining Plasma and Material Removal

[+] Author and Article Information
Soham S. Mujumdar

Department of Mechanical Science
and Engineering,
University of Illinois at Urbana-Champaign,
Champaign, IL 61801
e-mail: mujumda2@illinois.edu

Davide Curreli

Assistant Professor
Department of Nuclear, Plasma and
Radiological Engineering,
University of Illinois at Urbana-Champaign,
Champaign, IL 61801
e-mail: dcurreli@illinois.edu

Shiv G. Kapoor

Professor
Department of Mechanical Science
and Engineering,
University of Illinois at Urbana-Champaign,
Champaign, IL 61801
e-mail: sgkapoor@illinois.edu

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MICRO- AND NANO-MANUFACTURING. Manuscript received December 17, 2015; final manuscript received March 24, 2016; published online April 21, 2016. Assoc. Editor: Stefan Dimov.

J. Micro Nano-Manuf 4(2), 021006 (Apr 21, 2016) (9 pages) Paper No: JMNM-15-1085; doi: 10.1115/1.4033344 History: Received December 17, 2015; Revised March 24, 2016

In micro electro-discharge machining (micro-EDM), it is believed that electrical conductivity of the dielectric modified by additives plays an important role in discharge initiation and electrical breakdown, thereby affecting the process characteristics including process accuracy, material removal rate (MRR), and surface finish. However, there has been a lack of systematic efforts to evaluate the effect of dielectric conductivity in micro-EDM. This paper investigates the role of electrical conductivity of the dielectric on the breakdown, plasma characteristics, and material removal in micro-EDM via modeling and experimentation. Experiments have been carried out at four levels of electrical conductivity of saline water, i.e., 4 μS/cm, 362 μS/cm, 1106 μS/cm, and 4116 μS/cm, to study electrical breakdown of the dielectric and resulting craters. A global modeling approach is employed to model the micro-EDM plasma in saline water and predict the effect of dielectric conductivity on electron density, plasma temperature, heat flux to anode, plasma resistance, and discharge energy. It is found from both experiments and model-based simulations that increase in the dielectric conductivity facilitates the electrical breakdown of the dielectric by lowering the minimum breakdown potential at a given interelectrode gap. Experimental results also show increase in the volume of material removed per discharge when dielectric conductivity is increased, which is attributed to the increase in anode heat flux predicted by the micro-EDM plasma model. The model also predicts increase in electron density, decrease in plasma resistance, and decrease in discharge energy as the dielectric conductivity increases.

FIGURES IN THIS ARTICLE
<>
Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Uriarte, L. G. , Herrero, A. , Ivanov, A. , Oosterling, H. , Staemmler, L. , Tang, P. , and Allen, D. , 2006, “ Comparison Between Microfabrication Technologies for Metal Tooling,” Proc. Inst. Mech. Eng., Part C, 220(11), pp. 1665–1676. [CrossRef]
Heinz, K. G. , 2010, “ Fundamental Study of Magnetic Field-Assisted Micro-EDM for Non-Magnetic Materials,” M.S. thesis, University of Illinois at Urbana-Champaign, Champaign, IL.
Prihandana, G. S. , Mahardika, M. , Hamdi, M. , Wong, Y. S. , and Mitsui, K. , 2009, “ Effect of Micro-Powder Suspension and Ultrasonic Vibration of Dielectric Fluid in Micro-EDM Processes—Taguchi Approach,” Int. J. Mach. Tools Manuf., 49(12–13), pp. 1035–1041. [CrossRef]
Wang, J. , Wang, Y. G. , and Zhao, F. L. , 2009, “ Simulation of Debris Movement in Micro Electrical Discharge Machining of Deep Holes,” Mater. Sci. Forum, 626–627, pp. 267–272. [CrossRef]
Krishna Kiran, M. P. S. , and Joshi, S. S. , 2007, “ Modeling of Surface Roughness and the Role of Debris in Micro-EDM,” ASME J. Manuf. Sci. Eng., 129(2), pp. 265–273. [CrossRef]
Chow, H.-M. , Yan, B.-H. , Huang, F.-Y. , and Hung, J.-C. , 2000, “ Study of Added Powder in Kerosene for the Micro-Slit Machining of Titanium Alloy Using Electro-Discharge Machining,” J. Mater. Process. Technol., 101(1–3), pp. 95–103. [CrossRef]
Chung, D. K. , Shin, H. S. , Kim, B. H. , Park, M. S. , and Chu, C. N. , 2009, “ Surface Finishing of Micro-EDM Holes Using Deionized Water,” J. Micromech. Microeng., 19(4), p. 045025. [CrossRef]
Klocke, F. , Lung, D. , Antonoglou, G. , and Thomaidis, D. , 2004, “ The Effects of Powder Suspended Dielectrics on the Thermal Influenced Zone by Electrodischarge Machining With Small Discharge Energies,” J. Mater. Process. Technol., 149(1–3), pp. 191–197. [CrossRef]
Ito, A. , Hayakawa, S. , Itoigawa, F. , and Nakamura, T. , 2012, “ Effect of Short-Circuiting in Electrical Discharge Machining of Carbon Fiber Reinforced Plastics,” J. Adv. Mech. Des., Syst., Manuf., 6(6), pp. 808–814.
Yeo, S. H. , Tan, P. C. , and Kurnia, W. , 2007, “ Effects of Powder Additives Suspended in Dielectric on Crater Characteristics for Micro Electrical Discharge Machining,” J. Micromech. Microeng., 17(11), pp. 91–98. [CrossRef]
Jones, H. M. , and Kunhardt, E. E. , 1995, “ Development of Pulsed Dielectric Breakdown in Liquids,” J. Phys. D: Appl. Phys., 28(1), pp. 178–188. [CrossRef]
Zhu, T. , Zhang, Q. , Jia, Z. , and Yang, L. , 2009, “ The Effect of Conductivity on Streamer Initiation and Propagation Between Dielectric-Coated Sphere-Plate Electrodes in Water,” IEEE Trans. Dielectr. Electr. Insul., 16(6), pp. 1552–1557. [CrossRef]
Zhu, L. , He, Z.-H. , Gao, Z.-W. , Tan, F.-L. , Yue, X.-G. , and Chang, J.-S. , 2014, “ Research on the Influence of Conductivity to Pulsed Arc Electrohydraulic Discharge in Water,” J. Electrost., 72(1), pp. 53–58. [CrossRef]
Bernardes, J. , and Rose, M. F. , 1983, “ Electrical Breakdown Characteristics of Sodium Chloride—Water Mixtures,” 4th IEEE Pulsed Power Conference, Albuquerque, NM, pp. 308–311.
Ushakov, V. Y. , Semkina, O. P. , and Ryumin, V. V. , 1972, “ On the Nature of Pulse Electric Breakdown of Aqueous Electrolytes,” Appl. Electr. Phenom., 2, pp. 37–42. [CrossRef]
Tariq Jilani, S. , and Pandey, P. C. , 1984, “ Experimental Investigations Into the Performance of Water as Dielectric in EDM,” Int. J. Mach. Tool Manuf., 24(1), pp. 31–43. [CrossRef]
Kibria, G. , Sarkar, B. R. , Pradhan, B. B. , and Bhattacharyya, B. , 2010, “ Comparative Study of Different Dielectrics for Micro-EDM Performance During Microhole Machining of Ti-6Al-4V Alloy,” Int. J. Adv. Manuf. Technol., 48(5–8), pp. 557–570. [CrossRef]
Masuzawa, T. , Tsukamoto, J. , and Fujino, M. , 1989, “ Drilling of Deep Microholes by EDM,” CIRP Ann. Manuf. Technol., 38(1), pp. 195–198. [CrossRef]
Leão, F. N. , and Pashby, I. R. , 2004, “ A Review on the Use of Environmentally-Friendly Dielectric Fluids in Electrical Discharge Machining,” J. Mater. Process. Technol., 149(1–3), pp. 341–346. [CrossRef]
Nguyen, M. D. , Rahman, M. , and Wong, Y. S. , 2012, “ An Experimental Study on Micro-EDM in Low-Resistivity Deionized Water Using Short Voltage Pulses,” Int. J. Adv. Manuf. Technol., 58(5–8), pp. 533–544. [CrossRef]
Mujumdar, S. S. , Curreli, D. , Kapoor, S. G. , and Ruzic, D. , 2014, “ A Model of Micro Electro-Discharge Machining Plasma Discharge in Deionized Water,” ASME J. Manuf. Sci. Eng., 136(3), p. 031011. [CrossRef]
Mujumdar, S. S. , Curreli, D. , Kapoor, S. G. , and Ruzic, D. , 2015, “ Model-Based Prediction of Discharge Voltage and Current Waveforms in Micro-EDM,” ASME J. Micro Nano Manuf., 4(1), p. 011003. [CrossRef]
Lieberman, M. A. , and Lichtenberg, A. J. , 2005, Principles of Plasma Discharges and Material Processing, Wiley, New York.
“Table of Conductivity vs Concentration for Common Solutions,” https://www.grc.com
Mujumdar, S. S. , and Kapoor, S. G. , 2016, “ Effect of Dielectric Conductivity on Micro-EDM Characteristics Using Optical Spectroscopy,” International Conference on Micro-Manufacturing, Paper No. 79.
Mujumdar, S. S. , Curreli, D. , Kapoor, S. G. , and Ruzic, D. , 2015, “ Modeling of Melt-Pool Formation and Material Removal in Micro-Electrodischarge Machining,” ASME J. Manuf. Sci. Eng., 137(3), p. 031007. [CrossRef]
Lee, C. , and Lieberman, M. A. , 1995, “ Global Model of Ar, O2, Cl2, and Ar/O2 High-Density Plasma Discharges,” J. Vac. Sci. Technol. A, 13(2), pp. 368–380. [CrossRef]
“Morgan Database,” Last accessed Aug. 31, 2015, www.lxcat.net
Buxton, G. V. , Greenstock, C. L. , Helman, W. P. , Ross, A. B. , and Tsang, W. , 1988, “ Critical Review of Rate Constants for Reactions of Hydrated Electrons, Hydrogen Atoms and Hydroxyl Radicals (OH/O−) in Aqueous Solution,” J. Phys. Chem. Ref. Data, 17(2), p. 513. [CrossRef]
“Phelps Database,” Last accessed Aug. 31, 2015, www.lxcat.net
Baulch, D. L. , Duxbury, J. , Grant, S. J. , and Montague, D. C. , 1981, “ Evaluated Kinetic Data for High Temperature Reactions. Volume 4 Homogeneous Gas Phase Reactions of Halogen- and Cyanide-Containing Species,” J. Phys. Chem. Ref. Data, 10(Suppl. 1), pp. 1–721.
Knipping, E. M. , and Dabdub, D. , 2002. “ Modeling Cl2 Formation From Aqueous NaCl Particles: Evidence for Interfacial Reactions and Importance of Cl2 Decomposition in Alkaline Solution,” J. Geophys. Res. Atmos., 107(D8), pp. ACH-1–ACH-30.
Wang, L. , Liu, J. , Li, Z. , Huang, X. , and Sun, C. , 2003, “ Theoretical Study and Rate Constant Calculation of the Cl + HOCl and H + HOCl Reactions,” J. Phys. Chem., 107(24), pp. 4921–4928. [CrossRef]
Anicich, V. G. , 1993, “ Evaluated Biomolecular Ion-Molecule Gas Phase Kinetics of Positive Ions for Use in Modeling Planetary Atmospheres, Cometary Comae, and Interstellar Clouds,” J. Phys. Chem. Ref. Data, 22(6), pp. 1469–1569. [CrossRef]
DeMore, W. B. , Sander, S. P. , Golden, D. M. , Hampson, R. F. , Kurylo, M. J. , Howard, C. J. , Ravishankara, A. R. , Kolb, C. E. , and Molina, M. J. , 1997, “ Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling. Evaluation Number 12,” Jet Propulstion Lab, Pasadena, CA, JPL Publication 97–4, pp. 1–266.
Bortner, M. H. , 1964, “ The Chemical Kinetics of Sodium in Re-Entry,” Space Sciences Laboratory, General Electric Co., Report No. R64 SD33.
Patrick, R. , and Golden, D. M. , 1984, “ Termolecular Reactions of Alkali Metal Atoms With O2 and OH,” Int. J. Chem. Kinetics, 16(12), pp. 1567–1574. [CrossRef]
Silver, J. A. , Stanton, A. C. , Zahniser, M. , and Kolb, C. , 1984, “ Gas-Phase Reaction Rate of Sodium Hydroxide With Hydrochloric Acid,” J. Phys. Chem., 88(14), pp. 3123–3129. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Typical voltage and current waveforms of a successful micro-EDM discharge and a failed micro-EDM discharge (no discharge): (a) successful discharge and (b) no discharge

Grahic Jump Location
Fig. 2

Three-dimensional image of a typical micro-EDM crater showing positive and negative volumes: (a) 3D view and (b) side view

Grahic Jump Location
Fig. 3

Experimentally obtained voltage-gap domain at different electrical conductivities of water (σ0) showing discharge probability at each voltage-gap combination. White square represents probability ≥0.5, and gray represents probability <0.5: (a) σ0 = 4 μS/cm, (b) σ0 = 362 μS/cm, (c) σ0 = 1106 μS/cm, and (d) σ0 = 4116 μS/cm.

Grahic Jump Location
Fig. 4

Effect of water conductivity (σ0) on crater erosion volume at different gap distances and open gap voltage of 200 V

Grahic Jump Location
Fig. 5

Schematic of the micro-EDM plasma model formulation [22]

Grahic Jump Location
Fig. 6

Plot of wt.% of NaCl versus the electrical conductivity of the solution [24]

Grahic Jump Location
Fig. 7

Model-based prediction of voltage-gap domain at different electrical conductivities of water (σ0) obtained using micro-EDM plasma model. White square represents successful simulation of micro-EDM discharge at the voltage-gap combination, and dark square represents failure of the discharge predicted from the model. (c) σ0 = 1106 μS/cm and (d) σ0 = 4116 μS/cm.

Grahic Jump Location
Fig. 8

Model prediction of minimum breakdown potential versus gap distance for different water conductivities

Grahic Jump Location
Fig. 9

Model-based prediction of the effect of water conductivity (σ0) on the plasma characteristics at V0 = 200 V and L = 1 μm: (a) time-averaged electron density, (b) time-averaged plasma resistance, (c) total discharge energy, (d) time-averaged electron temperature, (e) time-averaged heat flux at anode, and (f) final plasma radius and time-averaged pressure (note suppressed zero)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In