Performance of Electrical Discharge Milling and Sinking in Micro Graphite Powder Mixed Dielectric

Marashi, Houriyeh; Sarhan, Ahmed A.D.; Maher, Ibrahem; Hamdi, Mohd

doi:10.4028/www.scientific.net/MSF.900.127

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Home Materials Science Forum Research and Application of Functional MaterialsPerformance of Electrical Discharge Milling and...

Performance of Electrical Discharge Milling and Sinking in Micro Graphite Powder Mixed Dielectric

Abstract:

Electrical discharge machining (EDM) is a non-conventional machining technique that is well-known for use in fabricating dies and molds owing to machinability of high hardness materials. Although the electro-thermal mechanism of EDM offers many advantages over other available machining methods, its sluggish nature limits the wide application of such machines for mass production. In this research, adding graphite powder to dielectric is proposed to improve EDM performance factors. Material removal rate (MRR) and average surface roughness (Ra) have been monitored and evaluated after addition of graphite powder to dielectric in electrical discharge milling and sinking. It is found that the presence of powder particles in dielectric fluid enhances the MRR steadily up to ~11 and ~17% for milling and sinking process, respectively. Moreover, the highest enhancement if Ra is ~31% at 1g/l graphite powder concentration for electrical discharge milling and up to ~11% for sinking process. Field emission scanning electron microscopy (FESEM) is used to inspect the machined surfaces. The surfaces machined with graphite powder mixed appear significantly unlike the surfaces machined in pure dielectric. Adding powder to dielectric is found to increase the machined surface hardness by ~26%, from 240 to 302 HV.

Info:

Periodical:

Materials Science Forum (Volume 900)

Main Theme:

Research and Application of Functional Materials

Edited by:

Prof. Osman Adiguzel and Prof. Yunqiu He

Pages:

127-130

DOI:

10.4028/www.scientific.net/MSF.900.127

Citation:

H. Marashi et al., "Performance of Electrical Discharge Milling and Sinking in Micro Graphite Powder Mixed Dielectric", Materials Science Forum, Vol. 900, pp. 127-130, 2017

Online since:

July 2017

Authors:

Houriyeh Marashi *, Ahmed A.D. Sarhan, Ibrahem Maher, Mohd Hamdi

Keywords:

Electrical Discharge Machining, Graphite Powder, Powder Mixed Dielectric, Powder Mixed EDM

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References

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[3] Marashi, H., et al., State of the art in powder mixed dielectric for EDM applications. Precision Engineering.

[4] Marashi, H., A.A.D. Sarhan, and M. Hamdi, Employing Ti nano-powder dielectric to enhance surface characteristics in electrical discharge machining of AISI D2 steel. Applied Surface Science, 2015. 357, Part A: pp.892-907.

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[7] Liew, P.J., J. Yan, and T. Kuriyagawa, Carbon nanofiber assisted micro electro discharge machining of reaction-bonded silicon carbide. Journal of Materials Processing Technology, 2013. 213(7): pp.1076-1087.

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Paper TitlePages

An Investigation into Surface Roughness of EDM Using Soft Particles Suspension in Silicone Oil

Authors: Yao Yang Tsai, Chih Kang Chang

Abstract: Electrical discharge machining (EDM) is an excellent technology to machining die and mold, but it is uneasy to obtain mirror-like surface. Powder-Mixed dielectric electrical discharge machining (PMD-EDM) is the innovative technology of EDM process, which can improve the quality of machined surface and applied in EDM finish machining now. The powder is usually hard particles, such as Al, Cu, Cr and Si in PMD-EDM. This paper presents a new research of PMD-EDM with suspending soft particles and abrasive grits in the dielectric fluid, especially focus on surface roughness. Experimental result shows the EDM process with polymer particles and abrasive grits can be carried out in silicone oil and the surface roughness has the finer improvement when increasing the rotation speed. Also, the effect of hard particles suspending in dielectric fluid are also discussed and compared. The surface roughness using polymer particles and abrasive in specific condition was better than only hard particles in silicone oil. Moreover, mixing abrasive and polymer in EDM can perform the polishing process.

430

Polishing Performance of Electro-Rheological Fluid of Polymerized Liquid Crystal Contained Abrasive Grit

Authors: Takeshi Tanaka

Abstract: In this study, we proposed an electro-rheological fluid-aided polisher (ERAP) using one-sided, patterned electrodes. The characteristics of ER fluid and ER fluid containing abrasive grit were investigated. The polishing performances of ER fluids with and without abrasive grit employing ERAP were verified and the following conclusions were obtained. Decreases in viscosity and in the ER effect were observed when highly polymerized liquid crystal (hereafter referred to as HPLC) was diluted with silicon oil. However, the mixing of abrasive grit increases the ER effect, but the ER effect of ER fluid containing abrasive grit decreased when mixed with abrasive grit. The viscosity decreased with increases in aliphatic saturated cyclic hydrocarbon oil (hereafter referred to as NCDM) mixed in highly polymerized compound (one kind of HPLC). The larger the positive dielectric anisotropy, the larger the ER effect in low-polymerized liquid crystal (hereafter referred to as LPLC). The smaller the grit size, the weaker the ER effect. When polished with HPLC, the polished surface was rough due to the large viscosity of an HPLC:silicon oil ratio of 4:14 mixed with #2000WA. However, the smallest surface roughness was attained at 0.5kV/mm for an HPLC:silicon oil ratio of 1:17 mixed with #2000WA. The surface quality was improved at an HPLC: silicon oil ratio of 1:17 mixed with #3000WA. When polished with LPLC, the surface roughness was improved by the increased ER effect when LPLC having a positive dielectric anisotropy was used. However, the surface roughness showed no change when LPLC with a negative dielectric anisotropy was used, due to its small ER effect.

123

Study of Dry Wire Electrical Discharge Grinding

Authors: Ying Ping Qian, Ju Hua Huang, Xi Zhi Zhou, Masanori Kunieda

Abstract: In this paper, the attempt was made to study dry WEDG (Wire Electrical Discharge Grinding), the differences between dry WEDG and wet WEDG, especially the rods appearance and material removal speed and surface roughness were studied experimentally, the results are as follow: (1) The shape especially the symmetry of the rods fabricated with WEDG using kerosene as dielectric fluid is better than that of dry WEDG only using pure air as dielectric. (2) The material removal speed is obviously higher in wet WEDG than that in dry WEDG. (3) The surface roughness of the rods fabricated with wet WEDG is lower than that with dry WEDG;.(4) The wet WEDG can be used in the roughness machining to improve the speed, and the dry WEDG can be used in the finishing machining to advance the surface quality.

2146

The Effect of Nb₂O₅ Addition on the Dielectric Properties of BaTiO₃-Based Ceramics

Authors: Yun Xia Zhang, Jun Jie Hao, Jun Ting Qi

Abstract: In this paper, the effect of Nb₂O₅ on the microstructure and dielectric properties of BaTiO₃-based ceramics has been investigated. In the study，Nb₂O₅ is added to the BaTiO₃-based ferroelectric material by conventional solid state synthesis. The structure is identified by X-ray diffraction method and SEM is also employed to observe the surface morphologies of the sample. The specimens of the ferroelectric doped with 2wt% Nb₂O₅ sintered at 1260°C for 1h exhibit attractive properties, its dielectric temperature coefﬁcient is lower than 15% over a wide temperature range from －55 to +180°C.

1108

Investigating the Effects of Powder Mixed Electrical Discharge Machining on the Surface Quality of γ–TiAl Intermetallic

Authors: B. Jabbaripour, M.H. Sadeghi, Mohammad Reza Shabgard, S. Shajari, H. Hassanpour

Abstract: Due to outstanding properties of γ–TiAl intermetallic such as high resistance against fatigue, oxidation, corrosion, creep, dynamic vibration, high working temperature and also its application in aerospace, automotive industry and turbojet engines; in this paper, powder mixed electrical discharge machining (PMEDM) of γ–TiAl intermetallic by means of different additive powders including aluminum (Al), graphite (Gr), silicon carbide (SiC), chrome (Cr) and iron (Fe) is investigated to compare the output characteristic of surface quality and roughness. The results indicate that aluminum powder produces the best surface finish, followed by silicon carbide, graphite, chrome and iron respectively. The experimental results show that in the determined settings of input machining parameters, aluminum powder can improve the surface roughness of TiAl sample about 32%.

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