The Temperature Distribution across the Gap in Electrochemical Machining

Abstract

The temperature of flowing sodium chloride solution within the ECM gap was measured by means of miniature bead thermistors in order to investigate the temperature distribution across the gap. Eight bead thermistors of 0.5mm∅ and three glass-tubed ones of 1.5mm∅ were inserted into the gap through the perspex wall and plane cathode electrode, respectively, so that their tips were protruded approximately 0.1mm∅ from the surfaces.
The measurements revealed the existence of a great temperature gradient in the vicinity of the cathode surface. The temperature rise near the cathode could become several times as great as the cross-sectional average value based on Joule's heating theory.
The significant influence of void fraction of evolved hydrogen gas bubbles was shown by a theoretical work and the experimental result that the higher back pressure yielded the smaller temperature rise.