Study on factors influencing hole diameter uniformity in electrochemical drilling of titanium matrix composites

Abstract

Titanium matrix composites (TMCs) are widely utilized in aerospace applications owing to their exceptional mechanical properties. Nevertheless, the incorporation of reinforced particles renders them challenging to machine. Electrochemical drilling (ECD) is extensively applied for drilling hard-to-machine materials due to its advantages, such as no tool wear and no induced residual stresses. Initially, during ECD experiments utilizing a cathode tool with a diameter of 20 mm, an “anomalous phenomenon” was observed for the first time, wherein the entrance diameter was significantly smaller than the balance diameter. Subsequently, we investigated the causes of this phenomenon through experimental and simulation analyses, comparing the impacts of factors like the height of the working ring and the flow field at varying depths. The factors influencing the size of the chemical reaction heat source and ohmic heat source in ECD were examined. Following this, a model for the process of achieving the balance temperature in ECD was developed, revealing that the disparity between the initial and balance temperature was the primary cause of this phenomenon. Finally, reducing the cathode outlet area by 70.8 % was found to effectively enhance the consistency of the hole size, achieving a reduction of more than 90 % in hole size variation.