The use of the recently developed 70-degrees bevel cutter with tangentially arranged positively raked carbide inserts (P40 grade) has led to the use of higher cutting conditions than those employed when milling the nickel-based nimonic 75 alloy with a 45-degrees approach-angle cutter having negatively raked carbide inserts. This paper discusses the results obtained with different cutter/insert combinations when machining nickel alloys under various cutting conditions. The K20 grade of cemented-carbide tools out-performed the K40 grade when milling with a 45-degrees approach-angle cutter due to their improved properties. Chipping and/or fracture of the tool edges were the dominant failure modes under most of the conditions tested, these being caused by a combination of high temperature and high thermal and mechanical stress, as well as adhesion of the work material on the tool rake-face during milling. Tool fracture can be caused also by attritional wear and thermal cracking mainly at the high temperatures usually generated under high cutting conditions. The positive cutter/insert combination results in a smooth cutting action, lesser power consumption and a very good surface finish.
