Milling of MAR-M247 nickel-based superalloy with high temperature and ultrasonic aiding

This study investigates the properties of machining MAR-M247 nickel-based superalloy combined ultrasonic vibration with high-temperature aided cutting. Taguchi experimental design was adopted to identify the influence of machining parameters on the machining characteristics. The six machining parameters, namely cutting tools for different materials; depth of cut; cutting speed; feed rate; working temperature; and, ultrasonic power. The machining characteristics analyzed include surface roughness, flank wear, cutting force, and milling temperature. According to the experimental results, when the cutting speed is greater than 90 m/min, P-type tungsten-carbide cutters with or without a Ti-alloy coating were unable to endure the very high temperatures generated in milling MAR-M247 nickel-based superalloy. The tungsten-carbide cutters melted and fractured. Due to the insufficient toughness of cermet cutters, the periodic high-impact stress causes severe cutter fractures when the cutting speed is greater than 60 m/min. When the cutting speed was less than 40 m/min, the cutter temperature was not significantly increased. Thus no melting or fracture of the cutters was found. Furthermore, when the cutting speed was less than 40 m/min, and fluid containing nano-particles of 5-23 nm in size was used, the cutter-workpiece friction force was reduced and the cutter life was extended.