In order to realize EDM with high accuracy, several factors which affect to the error in EDM were taken into consideration.
The in-process measurements of the force and the displacement of the main axis, the displacement of the head, the average current and the average voltage have been done at the same time.
The time series of measured date mentioned above are investigated mutually, and the following results are obtained.
(1) The main axis receives the force caused by the viscosity of dielectric fluid. This force becomes large in case of using the electrode with large area or in case of very small gap distance between the electrode and the work. The column is deformed by this force, and consequently machining accuracy becomes lower.
(2) Machined error by the force above-mentioned are expected to decrease by the improvement of the control performance of main axis.
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