Study on PCD Tool Wear in Hard Milling of Fully-Sintered 3Y-TZP Ceramics

Fully-sintered 3 mol % yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) ceramics have been recognized as a promising restorative material for dental applications because of their unique properties and superior biocompatibility. Hard milling using polycrystalline diamond (PCD) tools is a feasible strategy to shape the extremely hard ceramics into desired quality and target dimensions. The present paper aims to address the wear behaviors and mechanisms of PCD tools following the hard milling of 3Y-TZP ceramics. The workpiece specimens were prepared at the fully sintering temperature to completely porcelainize the zirconia substrate, and the PCD straight edge was brazed onto the tungsten carbide tool body along the tool axis direction to ensure the successful orthogonal milling of the workpiece specimen. A series of hard milling experiments were conducted by changing the spindle speed on a five-axis CNC machining center. The wear morphologies of worn PCD edges were examined using the scanning electron microscope (SEM) to identify the dominant wear modes and failure patterns governing the hard milling of 3Y-TZP ceramics. The effect of the spindle speed on the tool wear patterns was studied. The obtained results provide several technical guidance for the hard milling of fully-sintered 3Y-TZP ceramics.