Trochoidal milling and plunging strategies in rough pocket milling of aluminium alloys

Pocket milling is an essential issue in rough milling. Although the technology progress increased the machining capacities and enabled new machine structures, no significant evolution was observed about pocket milling trajectories. Trochoids and plunge milling are new types of strategies which have found practical applications in hard materials rough milling, especially die manufacturing. On a productivity point of view, they were not favourable until the development of high-speed machine tools. This paper aims at evaluating the potential of trochoidal milling and plunge cutting strategies in rough pocket millings. Algorithms were developed to generate trochoidal and plunge cutting trajectories for pocket milling, with cycle time optimisation regarding to milled surfaces quality. Then, an experimental campaign has been done to compare the new strategies with classical ones. The study focused both on productivity and quality issues. The influence of the machine tool capacities and architecture was also examined. Two different high speed milling dedicated machine tools were tested: a serial three-axis machine tool with "classic" dynamic capacities, and a parallel kinematics five-axis machine tool with high dynamic capacities. The results of this work leads to a better definition of the strengths and weaknesses of trochoidal milling and plunge cutting strategies in aluminium alloys rough machining with the focus to optimize the choice of strategies.