A Study on Preventing Cracks at the Small Hole Exit in Ultrasonic Machining Using a Wax Coating

Ultrasonic machining (USM) does not involve heating or any electrochemical effects, and subsequently causes low surface damage, has small residual stress, and does not rely on the conductivity of the workpiece. These characteristics are suitable for the machining of brittle materials, such as glass or ceramics. However, USM for brittle materials generates cracks on the workpiece while machining, especially at the hole exit with a small diameter. In this study, wax coating was used to deposit wax on the back side of the workpiece to decrease the occurrence of cracks at the exit holes in USM, and it was finally removed with a cleaning process. The experimental results show that this technique is beneficial for restricting the occurrence of cracks in glass or ceramics.