Journal of The Japan Society of Electrical Machining Engineers

[title in Japanese]

[in Japanese]

1983 Volume 17 Issue 33 Pages 1-17
Published: September 30, 1983
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2526/jseme.17.1

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Effect of the Electro-Discharge Machined Surface on the Mechanical Properties

On the Micro-Cracks Generated by EDM of Hardened Steels

Tadao TSUTSUI, Takeo TAMURA

1983 Volume 17 Issue 33 Pages 18-30
Published: September 30, 1983
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2526/jseme.17.18

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This paper deals with the micro-cracks which were generated by EDM of carbon steel (S45C) and tool steels (SK3 and SKD11). The cracks were studied experimentally under various machining conditions. The results are as follows:
(1) The critical pulse duration which does not generate the cracks is from 20 to 40μs for these steels and it becomes shorter as the peak current decreases.
(2) It is desirable to consider both the crack depth and the crack density when the surface damage occurs by the cracks. The crack depth becomes deeper with increasing pulse duration or peak current and the maximum depth of cracks is about 20μm.
(3) The cracks in S45C and SK3 are confined to the solidifying white layer and often the ones in SKD11 extend into the parent metal below the white layer.
(4) In order to reduce the surface damage based on the cracks, it is necessary to machine with he pulse duration which is as short as possible. And for this purpose the condition is suitable under which the spark machining is stable without localized arcing.

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Three-Dimensional Controlled EDM Using Column-Shaped Electrode (1st Report)

Changing Process of Electrode Shape on Ditch Forming

Masamitsu TSUCHIYA, Tsutomu KANEKO, Katsuya SUGANO

1983 Volume 17 Issue 33 Pages 31-44
Published: September 30, 1983
Released on J-STAGE: March 12, 2010

DOIhttps://doi.org/10.2526/jseme.17.31

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Introducing the computer technology, three-dimensional controlled EDM using simple-shaped electrode is put to practical use. This paper describes some basic researches on this method. There are more complicated problems on the three-dimensional controlled EDM than the one-dimensional method. And in order to develop the former method and to extend the area of application, it is important to grasp the basic machining characteristics, especially the changing process of the electrode shape. In this research an equipment on a trial basis of the three-dimensional controlled EDM, including a measure-compensating mechanism for the electrode wear length, is made, and some experiments are performed to form straight ditch using column-shaped electrodes. And the changing process of the cross sectional shapes of the ditches, exactly the shapes of the electrodes is considered. From the results of these experiments the following became clear mainly that the wear is progressed linearly in the radial direction in each part of the electrode, and that the process can be supposed on ditch forming with repeated several notchings.

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