Browsing by Author "Vaezi, Mohammad"

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    3D printing of PEEK-based medical devices
    (Infinite Science Publishing, 2019-09-12) Tafaoli-Masoule, Mojtaba; Shakeri, Mohsen; Seitz, Herman; Vaezi, Mohammad; Zahedi, S. A.
    Polyether-ether-ketone (PEEK) is an excellent thermoplastic alternative to metallic biomaterials which is used for loadbearing applications due to its high strength and stiffness, and biocompatibility with no cytotoxic effects. However, a potential clinical concern is that PEEK alone is not bioactive enough, and thus has limited fixation to bone. To overcome this problem, bioactive materials and/or porosity are incorporated into PEEK medical devices. The latest developments in these two strategies are presented. in this paper. Bioactive PEEK/hydroxyapatite (HA) prepared by integration of 3D printing and compression molding is presented in this paper. In addition, nozzle and build plate temperatures for 3D printing of porous PEEK were optimized using genetic algorithm (GA) to achieve the highest mechanical strength for load bearing applications such as spinal fusion cages.
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    Experimental investigation of process parameters in polyether ether ketone (PEEK) 3D printing
    (Sage, 2022-11-29) Tafaoli-Masoulea, Mojtaba; Shakeri, Mohsen; Zahedi, S. A.; Vaezi, Mohammad
    In the last two decades, polyether ether ketone (PEEK) has been vastly used in different industries such as automotive, aerospace, and medical sectors due to its mechanical strength, high heat stability, and excellent chemical resistance. Since this semi-crystalline polymer has a high melting temperature, the standard procedure to select extrusion-based 3D-printing working parameters has many challenges to ensure each bespoke product with the best quality. Slight shift from optimum process parameters in fused deposition modeling (FDM) of PEEK has a remarkable impact on the final product quality. The present research addresses the long-standing problem of selecting a working set-up quickly and accurately which is not dependent on the user's knowledge. In this manuscript, to identify the best arrangement of FDM process parameters, an orthogonal matrix of Taguchi Design of Experiments (DoEs) is applied. Different values of bed, chamber and nozzle temperatures, print speed, and layer thickness were thoroughly examined for the printing of standard tensile specimens. The mechanical properties and the fracture morphology of samples are examined in different printing conditions to explore a roadmap tool for designing better process parameters which satisfy mechanical requirements of products. In this study, the interpretation of the experimental results is investigated based on analysis of variance (ANOVA). The obtained results show that the best working set up for nozzle temperature, bed temperature, print speed, and layer thickness are 415 °C, 160 °C, 50 mm s-1, and 0.2 mm, respectively. This paper consists of five sections. After introduction in the first section, the effects of working parameters on the strength of final fused products are investigated in section 2. The results and the confirmation test are considered in section 3 and 4, respectively. The research is summarized in the conclusion part.