Effect of 3D Printing Process Parameters and Heat Treatment Conditions on the Mechanical Properties and Microstructure of PEEK Parts

Fused deposition modeling (FDM) processed Poly-ether-ether-ketone (PEEK) materials are widely used in aerospace, automobile, biomedical, and electronics industries and other industries due to their excellent mechanical properties, thermal properties, chemical resistance, wear resistance, and biocompatibility, etc. However, the manufacture of PEEK materials and parts utilizing the FDM process faces the challenge of fine-tuning a list of process parameters and heat treatment conditions to reach the best-suiting mechanical properties and microstructures. It is non-trivial to make the selection only according to theoretical analysis while counting on a vast number of experiments is the general situation. Therefore, in this paper, the extrusion rate, filling angle, and printing orientation are investigated to adjust the mechanical properties of 3D-printed PEEK parts; then, a variety of heat treatment conditions were applied to tune the crystallinity and strength. The results show that the best mechanical performance is achieved at 1.0 times the extrusion rate, varied angle cross-fillings with +/- 10 degrees intervals, and vertical printing. Horizontal printing performs better with reduced warpage. Additionally, both crystallinity and mechanical properties are significantly improved after heat treatment, and the best state is achieved after holding at 300 degrees C for 2 h. The resulting tensile strength is close to 80% of the strength of injection-molded PEEK parts.

Automated summary

In this study, the effects of adjusting the extrusion rate, filling angle and printing orientation on the mechanical properties of 3D-printed PEEK parts were investigated. Various heat treatment conditions were also applied to adjust the crystallinity and strength. The results showed that the best mechanical performance was achieved at an extrusion rate of 1.0 times, cross-fillings with +/- 10 degrees intervals, and vertical printing. Horizontal printing reduced warpage. Additionally, both crystallinity and mechanical properties significantly improved after heat treatment, with the best state achieved after holding at 300 degrees C for 2 hours. The resulting tensile strength was close to 80% of the strength of injection-molded PEEK parts.