Experimental identification of the functional scale for the machinability analysis of biocomposites

Abstract The machining process remains among the important challenges for the development of biocomposites. The main issues in the machining of biocomposites result from the multiscale cellulosic structure of the plant fibers. This specific structure induces high fiber deformation and high sensitivity to process parameters. Surface characterization of biocomposites for machining analysis should then consider this multiscale configuration to discriminate the effect of each material or process parameter. In this paper, the machined surfaces of flax/PLA biocomposites performed with the milling process have been analyzed using a white light interferometer at different analysis scales. Energetic analysis and Scanning Electron Microscope (SEM) observations of the machined surfaces have been carried out to compare with the results of the multiscale topographic measurements. Results demonstrate the significant impact of the analysis scale on the topographic assessment of the machined surfaces depending on the process parameters. The discrimination of the process parameter effects is not similar when varying the topographic measurement scale. By comparing with the microscopic SEM observations and the energetic analysis, the results of this work lead to identifying the relevant analysis scale for an efficient machinability qualification of unidirectional flax fibers reinforced PLA biocomposites.