Positioning performance of a hexapod machining cell under machining and nonmachining operations

Robotic machining is becoming increasingly popular in modern manufacturing owing to its cost and flexibility advantages. Compared with serial robots, a hexapod-based industrial robotic work cell has a much smaller footprint for equivalent rigidity. Thus, a comprehensive understanding of the hexapod’s positioning performance under machining and non-machining conditions is crucial to attain the desired robotic machining outcomes of the developed hexapod machining cell, which consists of two Fanuc F-200iB hexapods. The ballbar was chosen as the primary tool to measure the positioning performance, and a novel method based on the ballbar was proposed to facilitate measurement in various machining states. In the no-load running scenario, the positioning performance of the hexapod ranged from 33.8 µm to 99.3 µm (circularity) across 30 positions while considering thermal drift and feeding speeds. During the machining setup without cooling, the positioning performance of the hexapod machining cell demonstrated variations influenced by different machining parameters. Notably, spindle speed was identified as the most impactful factor, followed closely by feeding speed and cutting depth. By leveraging these findings, we enhanced the positioning accuracy of the robotic machining system through compensation, ultimately resulting in improved machining quality for future work.