Design of a pulse power supply unit for micro-ECM

Abstract

Electrochemical micromachining (µECM) requires a particular pulse power supply unit (PSU) to be developed in order to achieve desired machining performance. This paper summarizes the development of a pulse PSU meeting the requirements of µECM. The pulse power supply provides tens of nanosecond pulse duration, positive and negative bias voltages, and a polarity switching functionality. It fulfils the needs for tool preparation with reversed pulsed ECM on the machine. Moreover, the PSU is equipped with an ultrafast over current protection which prevents the toolelectrode from being damaged in case of short-circuits.The developed pulse PSU was used to fabricate micro tools out of 170µm WC-Co alloy shafts via micro electrochemical turning and drill deep holes via µECM in a disk made of 18NiCr6. The electrolyte used for both processes was a mixture of sulphuric acid and NaNO3 aqueous solutions.

A review on process capabilities of electrochemical micromachining and its hybrid variants

“…The short circuit protection helps in avoiding damage to electrical components in case of short circuit between electrodes during micro-ECM. [168] The major limitations on development of nanosecond pulsed power sources for micro-ECM are due to the technological limitation on maximum switching frequency (1 MHz) of conventional MOSFETs [171] and the effect of stray inductance and capacitance [168]. The stray capacitance delays the rise time of current pulses and also causes a significant overshoot at the end of pulse which is not desirable in ideal micro-ECM process.…”

Controlled Phase Interactions Between Pulsed Electric Fields, Ultrasonic Motion, and Magnetic Fields in an Anodic Dissolution Cell

“…Pulsed electric fields [1][2][3], ultrasonic velocity [4,5], and magnetic fields [6] are three common assistances used in an anodic dissolution electrochemical cell [7]. In anodic dissolution-based manufacturing processes such as electrochemical machining (ECM) and electrochemical finishing/polishing (ECF/P), these assistances have been reported to result in higher material removal rate (MRR), improved surface finish, increased accuracy, and higher electrical efficiency [7].…”

Design of an electrochemical micromachining machine

“…This is a substantial development and it is described in a separate paper [42]. In this paper only the capabilities of the pulse PSU are summarized.…”

“…The developed pulse PSU is equipped with an ultra fast overcurrent protection switching its semiconductors off with 50ns after a short-circuit has been detected [42]. The PSU is interfaced with the Power PMAC using optocouplers to guarantee the protection of the microcontroller but also to shift the logic level from 3.3V (on the PSU side) to 24V (on the Power PMAC side).…”

“…The different pulse PSU parameters and their respective range of values Figure 9. Drawing representing the different pulse shapes that can be produced with the self-developed pulse PSU [42] …”