Effect of Milling Parameters on Surface Characteristics and Mechanical Properties of Presintered Zirconia Ceramic

Abstract

In this research, a computer with integrated software connected to a Computer Numerical Control (CNC) milling machine was used to machine presintered Aconia zirconia samples as per the ASTMC1161-13 standard. The aim was to improve the surface characteristics and mechanical properties of presintered zirconia ceramic by varying cutting conditions such as depth of cut (0.1, 0.3, and 0.5 mm), rotational speed (6000, 9000, and 12000 rpm), and tool diameter (1.5 and 2.5 mm). Before sintering, using a bur diameter of 2.5 mm yielded the lowest roughness value of 0.76 µm at 9000 rpm with a depth of 0.1 mm. The surface roughness decreased as the cutting speed increased and cutting depth decreased. After sintering at 1500℃ for 2 hours at a rate of 8℃/min, the maximum hardness value of 1458.73 HV was obtained at 6000 rpm using a bur diameter of 2.5 mm. The highest flexural strength value of 566.67 MPa was obtained at a rotational speed of 6000 rpm, depth of cut of 0.1 mm, and tool diameter of 1.5 mm. The highest surface fracture toughness value of 414.94 MPa/mm 2 was obtained at a rotational speed of 12000 rpm, depth of cut of 0.5 mm, and tool diameter of 2.5 mm. Additionally, the use of high cutting speed during the milling processes reduced the mechanical properties of the Aconia zirconia, such as flexural strength and microhardness, when using a tool diameter of 1.5 mm. However, these mechanical properties increased when using a tool diameter of