Precision milling of zirconia toughened alumina (ZTA) with HF-CVD endmill tool

Sintered ceramics are recognized as promising materials for high-precision and advanced applications, such as orthopedic grafts implants, owing to their superior mechanical performance and biocompatibility. The fabrication of complex or intricate geometries often necessitates post-processing, for which micro-milling is frequently utilized. This paper focuses on the micro-milling of zirconia-toughened alumina (ZTA), a high-performance ceramic widely used in the medical industry for joint implants and rehabilitation components. The study investigates the surface formation mechanisms, size effects, and chip thickness characteristics associated with the process. In addition, the performance of cemented carbide micro-milling tools coated with a multi-layer HF-CVD diamond film is evaluated to assess their suitability for precision machining of ZTA ceramics. The tool wear mechanisms were systematically investigated, with particular attention given to the main failure modes occurring during the micro-milling process, including coating deterioration of the cutting tool. The surface formation and damage behaviour of ZTA under various cutting conditions were analysed in detail. Experimental results demonstrate that ZTA can be efficiently machined by micro-milling under controlled cutting parameters, achieving high surface quality and an industrially relevant tool life. The micro-milling of sintered ceramics remains challenging due to their inherent high strength and brittleness. Attaining the desired surface integrity and dimensional accuracy requires further optimization of machining parameters and strategies. Key aspects include the control of ductile-regime machining and the reduction of cutting near the tool center, both of which are critical to achieving improved performance.