Investigating the compression and fretting wear behaviour of FDM printed PLA samples for bone fixation

Abstract

ABSTRACT The metallic plate is used for bone fixation in biomedical applications, which causes health risks to the patient by leaching ion elements due to the formation of micro-motion between the plate and screw. Currently, the polylactic acid is favoured for replacing metal alloys in temporary implants due to the biodegradable property. However, polylactic acid has low mechanical properties compared to metal alloys and is not preferred as a fixation device. Therefore, the polylactic acid was printed using FDM technique under both horizontal and vertical orientations to improve the mechanical properties. After printing, the samples were post-heat treated at 60℃ for 24 h (B1) and 70℃ for 12 h (B2). Later, compression and fretting wear tests were performed for the printed and post-heat-treated samples to estimate the compression strength and fretting wear. The results indicated that the post-heat-treated horizontal sample B2 obtained a higher compression yield strength of 80.15 ± 3.53 MPa compared to printed and post-treated sample B1. This value lies within the range of bone fixation device. Moreover, a low coefficient of friction (1.34 ± 0.23) was obtained for sample B2 due to the improvement of yield strength. The worn morphology showed that the formation of cracks and spalling was more for the printed and B1 sample compared to the B2