Efficient layered plunge milling with low tool wear rate for axial flow impeller machining

Plunge milling is an efficient rough milling strategy of deep and narrow passages with difficult-to-cut material, due to its high axial stiffness and vibration suppression capability. However, for axial flow impellers with quasi-fan-shaped passages, uneven distribution of the radial cutting width in each plunge cycle commonly exists, which could not fully utilizing the cutting performance of the tool. This work proposes an efficient plunge milling strategy for five-axis rough machining of axial flow impeller passages. By dividing each passage section into upper and lower layers, the average radial cutting width is increased. To achieve maximum material removal rate, a quadratic optimization algorithm is designed to determine the optimal layering radius for each section under multiple geometric constraints. In addition, to decrease the excessive tool engagement angle caused by blade twisting at some plunge positions, a strategy for adjusting the plunge position sequence is proposed. Experimental validation is conducted on plunge roughing of a stainless-steel axial flow impeller. Experimental results show that compared with the conventional section-by-section plunge milling strategy, the proposed method can improve machining efficiency by 9.9%, and decrease the number of cutting edge pairs from 6 to 4.