The chip breaking problems when machining inconel 718 super alloy and chip breaker design

THE CHIP BREAKING PROBLEMS WHEN MACHINING INCONEL 718SUPER ALLOY AND CHIP BREAKER DESING(M.Sc. Thesis)Şener KARABULUTGAZİ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYSeptember 2006ABSTRACTThe reliability of machining operations is an essential requirement of modernautomatic manufacturing systems. Unbroken chips in the turning process arethe major obstacles for automation because long chips cause decrease inproductivity. Conventionally the chip breaking process is carried out bychanging cutting conditions or using chip breakers on the cutting tools. But withthese methods, chip control in turning inconel 718 is difficult because chips arecontinuous and can not be broken. Thus the development works of a chipbreaker for inconel 718 and mild steels still continue. This study has focused onthe chip-breaker design and experimental cutting of inconel 718 with thedesigned chip breaker. The process of chip breakage for inconel 718 usingcutting speed, depth of cut and feed rate variables were analyzed from theexperimental results.Inconel 718 was machined with a sementit carbide tool having two layers PVDcoated (TiAlN-TiN) at f=0,10, 0,15, 0,20, 0,30 mm/rev feed rates, a=0.5, 1, 1.5, 2mm dept of cuts and 30, 45, 60, 75 m/min cutting speeds using special designedrotary chip breaker with positive and negative tool holders. Chip pictures weretaken and surface roughness (Ra) values were measured. Chip breakabilityduring machining inconel 718 is dependent on DC motor speed and chipbreaker position on the cutting tool. The experimental results show thatdesigned chip breaker can break long chips in any cutting condition (whateverthe depth of cut, feed rate and cutting speed) and acceptable surface finish canbe achieved when machining Inconel 718 with designed chip breaker.Science code : 708.3.028Key words : Super alloys, inconel 718, chip breaker, dynamic chipbreaker, surface roughness.Page number : 103Adviser : Asist. Prof. Dr. Abdulkadir GÜLLÜ