Optimized sequence planning for multi-axis hybrid machining of complex geometries

The emerging hybrid machining platform potentiates the manufacturing of complex structures that are previously unmachinable solely by subtractive machining. The essence of such a platform is the alternation incorporating both additive and subtractive process. Multiple alternations are needed to eventually produce a complex model. The planning of the build-up height in each alternation plays a crucial role in the overall process: a large build-up height of partial construction may block the cutter from accessing the in-process part; conversely, frequent alternations will degrade the overall efficiency as well as the surface finish. In order to find a perfect balance, a metric called machinability is proposed to evaluate the subtractive machining feasibility. An efficient algorithm for calculating the machinability under the dynamic obstacle growing environment is then developed accordingly. Based on that, an efficient and deterministic TOP-DOWN_SEQUENTIAL_MAXIMIZATION algorithm is presented that is able to minimize the number of alternations while at the same time ensuring a smooth tool path for each subtractive operation. Ample computer simulation examples are given to illustrate the effectiveness of the proposed methodology.