Additive manufacture of PEEK cranial implants: Manufacturing considerations versus accuracy and mechanical performance

Abstract

High temperature laser sintering is an Additive Manufacturing (AM) process that allows fabrication layer by layer of complex structures in high performance biomaterial polymers such as Poly Ether Ether Ketone (PEEK) with high design freedom and short lead time. While studies on new material candidates for HT-LS are increasingly appearing, the quality standards of the parts obtained in HT-LS with special attention to the effects of the build orientation are less explored, thus limiting the implementation of AM PEEK in the healthcare sector. This study investigates the effect of four manufacturing build orientations - horizontal, oblique, vertical and inverted horizontal - on the properties of patient-specific laser sintered PEEK cranial implants. The mechanical performance in uniaxial static compression mode, the density variation and dimensional accuracy compared to the original design model are discussed. The implants manufactured in the horizontal and inverted horizontal orientations were found to show the least deviation from the design model and the highest compressive strength resistance. The vertically built implant showed the lowest accuracy in design and more of 70% lower first failure compared to the inverted horizontal implant.