Yongshou Liang

Feedrate scheduling for multi-axis plunge milling of open blisks

Multi-axis plunge milling has an increasing application in the manufacturing industry to rough machine open blisks. Its objective is to remove mass stock material with high efficiency and machining stability. In multi-axis plunge milling, cutting parameters are usually determined conservatively as constants to prevent excessive cutting forces and unexpected tool breakage. This is an obstacle to improve the cutting efficiency of rough machining. To address this issue, this article proposes an original approach to schedule the feedrate in multi-axis plunge milling of open blisks based on material removal rate. The material removal rate in plunge milling is directly proportional to the area of the cross section on the removed stock material. According to different types of the cross section, one feeding phase in plunge milling of open blisks is divided into three feeding stages. The cross section in each feeding stage is then identified with a mathematic and geometric method. Its area is then calculated by its constituting elements, such as a polygon, circular arches, and elliptical arches. After that, the feedrate is regulated to guarantee a constant material removal rate in the entire feeding phase. Experimental tests are conducted to verify the proposed feedrate scheduling method. This approach can reduce the cutting time and smooth the variances of cutting forces and torque in multi-axis plunge milling of open blisks.

Cutting forces, tool life, and size effect of passivated cutters in milling of Inconel 718

An experimental study is conducted to research the passivation effects of cutters on cutting forces, tool life, and size effect in milling of Inconel 718. Cutting forces and tool life of passivated cutters with different cutting edge radiuses are measured and compared in plunge milling. The results show that, with the increase of the cutting edge radius, cutting forces keep increasing while tool life increases first and then decreases. When the cutting edge radius is 7.9 μm the tool life of passivated cutter reaches its maximum under experimental conditions. The unit cutting force per cutting area on the tool edge is adopted to evaluate the size effect of passivated cutters in end milling. The results show the effect size of tool edge is obvious when the cutting depth is less than the cutting edge radius. This effect is more significant with the decrease of the cutting depth.