Investigation on the milling performance of amputating clamping supports for machining with industrial robot

In recent years, monolithic components have been broadly applied in aviation industry; however, the machining process is a severe problem. In the machining process of complex and large workpieces, six-degree-of-freedom manipulators provide more accessibility than traditional five-axis CNC machining centers and allow the integration of additional axes to extend the workspace. Therefore, industrial robots have been widely used in machining processes, such as chamfering, deburring, and polishing. Generally, material removal rates are relatively low in these applications because the dimensions of the parts are not required to modify. However, very few industrial robots have been applied in milling processes. One of the major obstacles is the chatter phenomenon due to the low rigidity and stiffness of industrial robots as a result of the serial structure. These drawbacks substantially decrease the accuracy of traceability. In this paper, a novel milling tool was presented for industrial robot milling. The milling experiment of 7050-T7451 aeronautical aluminum alloy workpiece was performed using a KUKA industrial robot (Model: KR210 R2700 extra). Vibration acceleration signals in the milling process at different spindle speeds and different milling methods were analyzed. The vibration acceleration signals in frequency were obtained using fast Fourier transform to investigate whether the chatter took place or not. Besides, chips and machined surface quality were analyzed with a handheld microscope. Finally, the optimal spindle speed, feed speed, and milling method were obtained by theoretical analysis and response surface methodology, which helps to overcome the deficiencies of industrial robot milling. The novel milling tool was shown to be able to remove the clamping supports effectively.