Experimental Investigations on a Parallel Kinematic Machine Tool and Validation Through Statistical Regression

Parallel kinematic machines (PKM) are ideal for complex multi-axis operations with enhanced accuracy. Their compact and modular design boosts flexibility in advanced manufacturing applications. The current research focuses on modeling and simulating a typical 3- Degrees of Freedom PKM (3-DOF/PKM) tool. The dynamic behavior and mode shapes of the 3-DOF/PKM are analyzed through modeling and experimental methods. Comparing the natural frequencies from experimental and model tests shows consistent results. Additionally, the machine's adequate structural stiffness with a rigid, well-supported frame is validated via model testing. Operational model analysis determines the spindle's shape, revealing that, compared to loaded conditions, vibration levels are lower during unloading, with responses concentrated around specific frequencies. The consequences of spindle rotational speed, feed per tooth, and depth of cut on the surface irregularity in the course of pocket milling of 6063 aluminum alloy are statistically validated. Taguchi analysis indicates that higher spindle speeds, especially 2500 rpm, lead to better surface quality. Optimal cutting parameters include 2500 rpm spindle speed, 95 mm feed per tooth, and 0.2 mm depth of cut. The spindle speed has a minimal impact of 10.35%, while feed per tooth is the most influential aspect at 47.88%. The low error margin and strong positive correlation confirm the model's reliability. Therefore, the effects of machining parameters are investigated using a limited number of experiments.