Improving machinability of Ni-based Monel 400 superalloy: a novel thermal-assisted drilling method based induction heating

Nickel-based superalloys are classified as hard-to-cut materials due to their low thermal conductivity, high strain hardening, and hot hardness. Consequently, the machinability of these materials, which are utilised in a variety of high-tech industries, remains the subject of ongoing investigation. Different methodologies have been proposed for this purpose; however, thermally assisted machining is considered to be one of the most significant methods employed to enhance the machinability of difficult-to-cut materials. This approach is based on the principle of reducing material strength and providing an easier cutting process. In the present study, the thermal-assisted drilling machinability of Monel 400 Ni alloy was investigated using an induction heating method, and the effects of this process on the workpiece were analysed comprehensively. The findings demonstrated that thermal-assisted drilling at moderate temperature (300 degrees C) ensures a considerable enhancement in machinability, providing a 19% reduction in force and 31% reduction in torque on average and a decrease in burr formation and tool wear, without inducing substantial alterations in the material's internal structure. However, whilst the process at elevated temperatures (600 degrees C) enhances machinability by reducing thrust force and torque by approximately 51%, substantial alterations in the material microstructure and a reduction in hardness and yield strength of approximately 9% are observed post-processing.