Longitudinal and Tangential Coefficients of Chip Compression in Orthogonal Wood Cutting

The complexity of the cutting zone makes it impossible to establish a reliable, simple, and comprehensive mathematical model for orthogonal wood cutting. Thus far, the science of cutting materials have used only approximate and simplified engineering theories that attempt to explain the mechanisms of chip shaping. The research of wood processing by chip separation is mostly based on models developed for metal processing. By applying Astakhov's model to orthogonal wood cutting, the total cutting power is divided into four components, and each cutting force component can be theoretically related to the coefficients of chip compression. In the present study, longitudinal, and tangential coefficients of chip compression were determined experimentally during orthogonal cutting of wood in the longitudinal (0 - 90) direction depending on wood moisture content (MC) and cutting speed. The direction of the fibers, cutting speed, and MC influenced the coefficient of chip compression. The MC of wood above the fiber saturation point significantly changed the impact of the cutting speed on the tangential coefficient of chip compression. In order to explain and better understand the obtained results of chip compression coefficients, the modulus of elasticity (MOE) of wood samples with different MC was determined. The MOE was calculated from the compression tests on small specimens in tangential and longitudinal direction.