An eccentric sleeve grinding strategy for fibre-reinforced composites

Abstract

Though Fibre Reinforced Composites (FRCs) can be manufactured with minimum damage using the state-of-the-art-innovative practices, inevitable machining operations on them during functional applications may invite further damages in matrix, fibre and interfaces. Surface grinding in its various capacities and hybrid forms has been demonstrated as one of the potential techniques for material removal in FRCs. However, effects of grinding forces on damages such as trans-laminar cracks in conventional grinding is proportional to the depth of cut for all fibre orientations. This paper introduces a new methodology referred to as eccentric sleeve grinding (ESG), with an intermittent progressive cutting strategy to minimize the machining defects on FRCs. Configuration of ESG will establish an eccentric grinding wheel rotation with cutting and non-cutting zones for abrasive grains, establishing a step-by-step cutting scheme without severe fibre-matrix fracture or fibre pull-out. A mathematical model for ESG is derived to assess the grinding forces and material removal, with experimental validation using conventional aluminium oxide wheel on bi-directional carbon fibre reinforced composite. The significantly lower magnitude of grinding forces, improved grinding force ratio and reduced surface roughness were observed in ESG, in comparison with conventional surface grinding for all the selected depths of cut from 20 to 100 μm. Microscopic topography studies on surfaces generated through conventional and eccentric sleeve grinding were clearly illustrating the effectiveness of the progressive cutting strategy in ESG. The ESG configuration presented in this paper can be adopted appropriately for minimal damage machining of FRCs, even using a traditional surface grinding machine.