Machining and surface integrity of fibre-reinforced plastic composites

Abstract

The current focus of manufacturing research on fibre-reinforced plastics (FRP) is composed of the search for efficient processing techniques capable of providing high quality machined surfaces. Very limited work has been performed to identify the influence of manufacturing processes like edge-trimming and drilling on material performance. Recent reports suggest that process-induced damage may affect the mechanical behaviour of FRP materials. Therefore an experimental study of orthogonal cutting was conducted on the edge trimming of unidirectional and multi-directional graphite/epoxy composites with polycrystalline diamond tools. The effects of tool geometry and operating conditions were evaluated from an analysis of chip formation, cutting force, and machined surface topography. All aspects of material removal were found to be primarily dependent on fibre orientation. Discontinuous chip formation was noted throughout this study, regardless of machining parameters. Three distinct mechanisms in the edge trimming of fibre-reinforced composite material including a combination of cutting, shearing, and fracture along the fibre/matrix interface were observed. An investigation conducted on the compression, flexural and impact strength of graphite/epoxy composites machined by both traditional and non-traditional techniques, confirms that manufacturing characteristics may not only affect bulk properties but also influence the initiation and propagation of failure. © 1997 Indian Academy of Sciences.