AN EXPERIMENTAL STUDY ON EDGE CHIPPING IN ULTRASONIC VIBRATION ASSISTED GRINDING OF BIO-CERAMIC MATERIALS

摘要

Bio-ceramics have been widely employed in dental restorations, repairing bones, and joint replacements etc. due to their high compressive strength, superior wear resistance, and natural aesthetical appearance. Abrasive machining processes such as grinding have been used to obtain a smooth surface and desired dimensions for bio-ceramic parts. However, a major technical issue resulted from abrasive machining processes is edge chipping. The edge chipping could lead to the failure of bio-ceramics and has to be removed by downstream processes. It not only increases machining cost but also introduces potential deficiencies into the bio-ceramic parts. This paper present an experimental study on the edge chipping in ultrasonic vibration assisted grinding (UVAG) of bio-ceramic materials. An innovative UVAG system is developed and employed to machine three bio-ceramic materials (Lava, partially fired Lava, and Alumina). The effect of ultrasonic vibration on the edge chipping is investigated by observing under scanning electron microscope (SEM). The experimental results show that the edge chipping can be significantly reduced with the assistance of ultrasonic vibration. For the diamond grinding, there exist a lot of edge chippings along the machined slot edge that varies from 0.3 mm to 1.2 mm, whereas for the UVAG, there are only several tiny edge chippings with size from ～0.03 mm to ～0.1 mm along the machine slot edge. The results indicate that the UVAG system developed has a great potential to be used in production to improve bio-ceramic materials' surface integrity, in particular, edge chipping quality.