Influence of cutting conditions on machinability aspects of PEEK, PEEK CF 30 and PEEK GF 30 composites using PCD tools

Polyetheretherketone (PEEK) composite belongs to a group of high-performance thermoplastic polymers, which has high specific properties as compared to conventional metallic materials. Due to its own properties and potential applications in various fields of structural components, it is necessary to investigate the machining of PEEK composites. The present study establishes the relationships between the cutting conditions (cutting speed and feed rate) on two aspects of machinability, namely, power and specific cutting pressure by developing second order mathematical models based on response surface methodology (RSM). The study also focuses on interaction effects between the controllable factors and responses during machining of unreinforced and reinforced PEEK composites using polycrystalline diamond (PCD) tools. The experiments have been planned as per full factorial design (FFD) of experiments. Three types of PEEK composites such as unreinforced polyetheretherketone, reinforced polyetheretherketone with 30% of carbon fibres (PEEK CF 30) and 30% of glass fibres (PEEK GF 30) were used for the machining tests. The analysis of variance (ANOVA) was performed to check the adequacy of the mathematical models. The parametric analysis reveals that, power increases with increase in feed rate while the specific cutting pressure decreases for all the materials tested. The analysis also shows the dependency of both power and specific cutting pressure on cutting conditions. The investigation illustrates that the addition of reinforcements to PEEK in order to improve the material properties affects the machinability. (C) 2008 Elsevier B.V. All rights reserved.