The role of PEEK viscoelasticity in chip formation, surface finish and geometrical accuracy

Polyether ketone (PEEK) is widely used in biomedical applications, where achieving an optimal surface finish and accuracy is essential. This study examines PEEK's cutting response under dry and cryogenic conditions at various cutting speeds. The results demonstrated that, even if PEEK was machined in a glassy state, chip fragmentation was only possible if viscoelasticity was suppressed. Furthermore, achieving a good surface finish depended on the combined effects of temperature and deformation rate. The study also revealed that the enhanced stiffness of PEEK under cryogenic cooling contributed to improved geometrical accuracy when machining the inner surface of biomedical acetabular cup inserts.