Feasibility study of manufacturing microgrooves on beryllium with electrochemical machining

Abstract

Beryllium is a rare metal with many excellent properties, which make it increasingly meaningful for manufacturing precise instruments especially in the aerospace industry. Most of the small size beryllium parts consist of microgrooves that play an important role during use. In this paper, we adopted electrochemical machining (ECM) technology to process sub-millimeter microgrooves successfully on beryllium. The influences of both the electrolyte and feed rate were analyzed in detail. As a result, sodium chloride (NaCl) electrolyte always causes strong pitting corrosion, while the ECMed surface is smoother with a low concentration of sodium nitrate (NaNO3). The cross-section of the microgroove is semi-elliptical. The depth decreases, and the width remains unchanged as the feed rate increases. Flow marks appear at the bottom as a result of the gas diffusion and cathode chattering. Electrolyte of 10% (mass fraction) NaNO3 and a feed rate of 10 mm/min were considered as the proper configuration to achieve a 350 μm × 56 μm microgroove on beryllium with a Ф320 μm stainless steel cathode. Finally, a structure with uniform microgroove width has been fabricated.