Journal of The Japan Society of Electrical Machining Engineers
Online ISSN : 1881-0888
Print ISSN : 0387-754X
ISSN-L : 0387-754X
Volume 48, Issue 118
Displaying 1-3 of 3 articles from this issue
Paper
  • - Relationship between change in surface magnetic flux density and magnet internal temperature with discharge conditions -
    Hideki TAKEZAWA, Yoshihiro ICHIMURA, Naotake MOHRI
    Article type: Paper
    2014 Volume 48 Issue 118 Pages 100-107
    Published: 2014
    Released on J-STAGE: May 25, 2015
    JOURNAL FREE ACCESS
     It is difficult to perform traditional machining of a permanent magnet, which is a functional material, because of its brittleness and magnetic forces. However, electrical discharge machining (EDM), which is a noncontact machining method, has been used for shape machining of magnetic materials. Magnetic materials have a Curie point; therefore, their magnetic flux density decreases when they are heated to a high temperature. Because EDM is a thermal process, it has the potential to control the magnetic flux density of a machined surface. In this study, to clarify the influence of magnetic flux density on a machined surface, the following machining conditions were investigated: the Duty Factor (D.F.) and internal temperature. The results showed that the influence of the magnetic flux density was small under low-energy machining conditions. In contrast, under high-energy machining conditions or a high D.F., the magnetic flux density significantly decreased compared with the initial value. These results have confirmed the importance of machining conditions for EDM of magnetic materials.
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  • Tatsushi SATO, Seiji SATO, Hidetaka MIYAKE, Koichiro HATTORI, Hitoshi ...
    Article type: Paper
    2014 Volume 48 Issue 118 Pages 108-117
    Published: 2014
    Released on J-STAGE: May 25, 2015
    JOURNAL FREE ACCESS
     Wire-break, which greatly harms machining performance, can be prevented by reducing the ma- chining energy. However, too much reducing the energy also harms machining speed. Thus control algorithm which brings minimum requirement for wire-break prevention is needed. In this paper, we clarify there exists energy limit that brings wire-break, and the limit changes according to two factors: the workpiece thickness and the flow of dielectric fluid. In addition, we propose the control algorithm for wire-break prevention, which detect these two factors automatically. It is also shown that this control algorithm brings much higher performance when these two factor change during machining.
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  • Tatsushi SATO, Shigeru MATSUNO, Daisuke ECHIZENYA, Takeyuki MAEGAWA, H ...
    Article type: Paper
    2014 Volume 48 Issue 118 Pages 118-127
    Published: 2014
    Released on J-STAGE: May 25, 2015
    JOURNAL FREE ACCESS
     A method of slicing solar-grade silicon into thin wafers is greatly demanded because of the rapid increase in the production volume of photovoltaic cells. Wire electrical discharge machining seems to be a suitable slicing method because it is a noncontact process that hardly cracks wafers. However, solar-grade silicon is not so highly conductive that it is difficult to slice it by wire electrical discharge machining. In this paper, we propose a new machining power supply suitable for slicing solar-grade silicon, which causes minimum damage to the machined surface. We also show that photovoltaic cells made from the wafers sliced by wire electrical dischage machining are comparable to conventional cells. We conclude that wire electrical discharge machining can be one of the practical methods of slicing solar-grade silicon.
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