Finite element analysis of orthogonal cutting of cellular metals: influence of cutting conditions on chip formation and surface damage

Cellular metals are highly porous materials with very distinctive properties. Although it is possible to manufacture near-net-shape parts of these materials with some manufacturing processes, additional machining operations are usually required. However, as conventional machining causes surface damage and poor precision, finishing operations are often performed using alternative, cost-intensive methods. In the present work, a mesoscopic finite element model was used to analyze the influence of cutting conditions and tool geometry in the orthogonal cutting process of cellular metals. The study considered the variability of the mesostructure, as the behavior of multiple cell arrangements under cutting conditions was evaluated. The influence of cutting speed, depth of cut, and tool rake angle on chip formation and surface damage was explored. Chip formation at higher cutting speed was different, as chip fragmentation was visible. Tools with a positive rake angle and a higher cutting speed led to a decrease in subsurface damage. Nevertheless, surface quality is markedly dependent on the stochastic nature of the mesostructure, as material separation is defined by the response of the cell array. Hence, a set of cutting parameters for optimal surface quality could not be identified.