Measurement of Process Reaction Force in EDM using Hopkinson Bar Method.

This paper describes the measurement of the process reaction force that is generated in EDM using Hopkinson bar method. The reaction force is an integral of both the pressure inside the bubble and that in the dielectric liquid over the working surface area. Using the Hopkinson bar method, the correct waveform of the process reaction force was obtained without influenced by the natural frequency of the measuring system. The results show that the reaction force reaches almost 100N in a semi-finishing condition in a single pulse discharge when the discharge gap is filled with a working fluid. Besides, the measured results were compared with the calculated results which were obtained by neglecting the viscosity of the working fluid under various machining conditions, and the relationships between the reaction force and machining conditions were investigated.