Model based assessment of maximal surface temperatures and heat flow in edge trimming of UD CFRP with tools of different type

Abstract

Excessive heating during edge trimming of CFRP components leads to matrix degradation impairing their quality. The thermal response of unidirectional CFRP when machining with different tool types is studied: PCD cutters, coated carbide routers, and diamond grinding pins. Temperature and torque were measured at various fibre orientation angles Φ and cutting conditions. Based on an analytical model, key thermal parameters were identified from experimental data. For all tools, temperatures exceeded the matrix glass transition temperature under most conditions. Maximum of temperature changes was observed at Φ = 135°, minimum at Φ = 90° was most pronounced for the cutter, less noticeable for the router, and almost absent for the grinding pin. At Φ = 90°, the thermal contact length and heat flow ratio typically reached maximum values, while the heat flux was at its lowest. Regarding cutting conditions for both the cutter and router, an increase in cutting speed led to higher equivalent heat flux, heat flow, and temperature change. In contrast, for grinding pins, temperature change increased at the lower cutting speed or feed rate. In grinding, heat flow, equivalent heat flux and thermal contact length were primarily influenced by the fibre orientation symmetry angle, whereas heat flow and equivalent heat flux were nearly independent of the cutting conditions. Thus, the tool types exhibit different thermal parameters and patterns of their dependencies on the machining conditions, which are differentiated by the model and can be explained by pulsed point, pulsed linear or continuous surface contact of individual cutting edges.