Effect of Aspect Weight and Machining Progression on Machinability: Modeling and Machining Case Study

The machinability of workpiece is varying with the progressing of machining and cannot be evaluated from a specific cutting moment. In this work, a global machinability evaluation method with considering tool wear progression was proposed by weighted accumulating of machinability at different cutting moment, where the machinability weight at specific cutting moment was determined as the relationship of instantaneous tool wear rate to average tool wear rate through the tool life. When turning AISI D2 steels with conventional and wiper inserts, the machinability of different inserts deteriorates to different degrees with the progressing of machining. As a result, the conventional and wiper inserts showed opposite trends of machinability under different cutting moment. In addition, the wiper inserts perform better machinability at depths of cut a_p = 0.2 mm (with an improvement of 7.5%) and a_p = 0.4 mm (with an improvement of 2.7%), while worse machinability at a_p = 0.6 mm (with a reduce of 23.4%) than the conventional inserts. The results indicated that the wiper inserts were suitable for turning with depth of cut less than 0.4 mm. In addition, another interesting finding was that the machinability evaluation with a sharp cutting tool would lose its production significance because of the fast tool wear rate, which contributed a negative weight to the global machinability. This work is potential to improve the machinability evaluation system and, in turn, better guide the production practice.