is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. AbstractRecently, natural fiber reinforced plastic (NFRP) materials are becoming a viable alternative to synthetic fiber in many industrial applications which not require high structural performances. However, machining of NFRP such as milling process is almost unavoidable operation to facilitate the parts assembly in addition to the finishing of final products. The present study thus focused on the influence of natural fiber types on tribological behavior during profile milling process. Three types of short natural fibers (bamboo, sisal and miscanthus) reinforced polypropylene (PP) composites are investigated. The quality of NFRP machined surface is quantified using a multi-scale analysis based on wavelets decomposition. The natural fiber effect related to the machined surface quality is hence identified at all scales from roughness to waviness. The Bamboo fibers reinforced plastics which exhibit high contact stiffness shows the smoother surface finish after machining. Therefore, the multiscale surface roughness is used as descriptor of natural fiber's influence on the machining mechanisms and to establish the cutting signature of NFRP materials.

This work aims to investigate the tribological effects of coated tools on the surface finish of natural fiber reinforced plastics (NFRP) during profile milling process with particular emphasis on the natural fiber cutting mechanisms and tool wear. Both up-milling and downmilling configurations were considered. The cutting experiments were carried out on unidirectional flax fibers reinforced polypropylene resin (UDF/PP) using three different cutting tools. Uncoated tungsten carbide, titanium diboride (T i B 2 ) coated and diamond coated were used to conduct profile milling tests. Tribological cutting contacts were evaluated by measuring the specific cutting energy. Surface state was acquired by scanning electronic microscope (SEM) and optical microscope (OM). Surface topography was measured using 2D Surfascan stylus profilometer. Machined NFRP surface finish was characterized using standard and multiscale analysis based on wavelets transform.Results show that the cutting edge radius made by tool coating has a significant effect on surface finish. Natural fiber shearing is more efficient once the removed chip thickness exceeds the cutting edge radius value. Moreover, it had been demonstrated that the pertinent scales for surface finish analysis are between 50 µm and 1 mm which correspond to the multiscale fiber reinforcement structure. Furthermore, and unlike the uncoated tool, T i B 2 and diamond coatings allow a good wear resistance of the cutting tools against the tribological solicitations of flax composites machining.

The present study is focused on tribological and multiscale analysis for the machined surfaces of bidirectional flax fibers reinforced polypropylene composites. This is to track the multiscale effect of the helix angle of the cutting tool, related to its kinematic, on the cutting mechanisms. The results show that the helix angle has significant effect on the tribological performances which affect the tribo-contact interaction between the flax fibers and the cutting edge. The fibers orientation in the woven reinforcement has significant effect on the surface quality. The multiscale analysis reveals the pertinent scales that activate the helix angle effect.