Prediction of cutting forces, damage locations and machined surface integrity in machining of circular-cell honeycomb composites: Simulations, parametric effects and experimental validations

Abstract

The machining of honeycomb cores presents challenges due to exerted unbalanced cutting forces from discontinuous hexagonal structures, where severe tool wear and cracking on the machined surface occurs. In this study, the established cutting force models consider alterations of the wall thickness and immersion angles when mono-oblique and duplex-oblique cutting tools are engaged. The maximum cutting forces and the produced damages compared to the tool positions are analytically simulated and validated. The increased cutting temperatures and the shear stress gradients with respect to cutting speeds and feed rates were analysed after fitting them with the experimental results. Moreover, the vibration-induced cutting-edge-rounding and fracturing on the machined surface were identified. In the validation experiments, a wide range of cutting speeds (100–300 m/min) and feed rates (0.2–1.0 mm/rev) were operated for practical utilities. It was proven that the highest cutting forces (∼26.59 N) took place at the entry node of the hexagonal cell; whilst the cutting forces’ fluctuations (±20.35 N) under high frequency (∼2.5 kHz) and high intensity (∼ 8290 dB) could result in cutting-edge rounding from tool wear. The damage locations on the machined surfaces, as well as the corresponding fracturing mechanisms of fibres incubating the in-plane and out-of-plane cracks were verified and discussed.