Influence of the green-machining parameters on the mechanical properties of alumina rods

Abstract

Green and white machining has being extensively employed in compact blanks to obtain a pre-form prior to the sintering of advanced ceramics. Both machining processes involve low-energy consumption and high material removal capacity. Green machining is more sustainable than white machining; however, its use should be more demanding because of the complex binder links between ceramic powders. The goal of this work is to identify the limits of aggressive cutting through measures of machining forces on green specimens and its correlation with the mechanical properties of sintered alumina rods. Rod specimens were obtained from alumina-PVAl granules compacted at 100 and 200 MPa, thermal annealed and green machining employing a head with aerostatic bearings. Gradual introduction of critical defects on the surface due to the action of the wheel was detected. Surface without damage was detected with a material removal rate of 10,000 mm3/min and with power consumption of 1700 W. The speed limit that was identified resulted in the rupture of the specimen, depending on the depth of cut, which exceeded the mechanical strength. The correlation between power consumption and rate of removal proved to be critically important processing parameters for the design of machining in green ceramic.