Statistical study of surface roughness in turning of peek composites

The present paper is aimed at studying the impact of cutting conditions on surface roughness in turning of polyethertherketone (PEEK) composites. The latter are widely used in manufacturing industry and possess excellent mechanical and thermal properties. Statistically designed experiments were carried out for unreinforced PEEK, reinforced PEEK with 30% of carbon fibres and reinforced PEEK with 30% of glass fibres using two different cutting tool materials namely, polycrystalline diamond (PCD) and K15 cemented carbide and considering feed and cutting speed as the crucial cutting conditions. Surface roughness is represented by five different profile amplitude parameters. By applying statistical multi-regression analysis and analysis of variance to the experimental data a predictive model is developed revealing that feed exerts the strongest influence on roughness, whilst cutting speed has a secondary effect. Other interesting remarks made are that the unreinforced PEEK presents the smallest roughness values, the presence of glass fibres increases roughness more than carbon fibres and the PCD tool tends to provide lower roughness.