Effects of short glass fibre reinforcement on the machinability of PEEK polymer based on cutting force monitoring and geometric control

Polyetheretherketone (PEEK) is a semi-crystalline thermoplastic that plays an important role in industry due to its properties such as high strength-to-weight ratio, chemical resistance, and biocompatibility. PEEK properties can be enhanced by adding various types of reinforcement to the polymer matrix, including nanomaterials, particles, and fibres in both short and long form. Moreover, PEEK-based polymers require a machining process for finishing operations when high geometric precision is demanded. This study assessed the effects of short glass fibre addition on the machinability of PEEK polymer by milling. The machinability analysis was carried out by longitudinal and circular edge milling operations. The impact of the cutting conditions – feed per tooth, radial depth of cut, and spindle speed – and the effects of milling type – up or down milling – on the machinability of two PEEK-based materials were evaluated. Furthermore, the three orthogonal cutting force components were monitored during the machining tests. Machinability was characterised using both performance and consumption parameters i.e., the specific cutting energy, and geometric parameters i.e., dimensional accuracy, roundness error, and surface roughness. The results showed the addition of short glass fibres to the PEEK polymer improved machinability in terms of specific cutting energy, dimensional accuracy, and roundness error, but worsened surface texture. For longitudinal edge milling, the best results in terms of specific cutting energy, dimensional accuracy, and surface roughness were achieved with up milling, whilst for circular edge milling, the optimum results in terms of dimensional accuracy and roundness error were obtained with down milling. • The effect of glass fibre addition on PEEK machinability was assessed. • Linear and circular edging milling using up and down milling were evaluated. • Specific cutting energy and geometric properties were analysed. • Response surface based on ANNs predictive models were used for data analysis. • Glass fibres addition to PEEK improved geometric behaviour except surface texture.