Evaluation of minimum quantity lubrication effects by cutting force signals in face milling of Inconel 182 overlays

Nuclear steam turbines are well known working in saturated wet steam environment, it is essential to avoid critical components such as rotor from erosion and corrosion. The use of anti-corrosion material depositing and covering on the steam seal and then machining to the required thickness and surface quality can be an effective and economical way to prevent rotor supporting plane from corrosion and erosion. Inconel 182 can be this anti-corrosion material, however, it is also difficult-to-cut material. Due to its strong adhesive property, the environmentally friendly lubrication technology Minimum Quantity Lubrication (MQL) is required when machining Inconel 182 overlays. This study investigates the machinability of Inconel 182 overlays under dry cutting condition and MQL cutting condition during up milling or down milling orthogonal tests. The lubrication/cooling effects of MQL are also evaluated by real-time monitoring and analyzing cutting force signals in time-domain and in frequency-domain. Results indicate that cutting force signals, especially in transverse direction, can be used accurately to estimate the lubrication/cooling effects of MQL. MQL works effectively in up milling because, in this case, tool wear is dominant. However, in down milling, the self-excited vibration due to large impact when tool cut into the workpiece is easily intensified by the high speed MQL droplets, in this case, MQL works ineffectively. Considering the resource efficiency and economics, machining Inconel 182 overlays using up milling with MQL can effectively reduce tool waste and manufacture costs.