OBRABOTKAMETALLOV Vol. 26 No. 4 2024 TECHNOLOGY components printed by FDM with a printing orientation angle of 0° are most suitable for parts susceptible to wear, followed by components with a printing orientation angle of 90°. Components manufactured with a printing orientation angle of 45° should not be applied. Conclusion This study demonstrates the wear characteristics of PLA material in a friction pair with SS 316 stainless steel to determine the optimal parameters. FDM printing was used to create the specimens with diff erent printing orientation (0°, 45°, 90°). The experiments were conducted using the pin-on-disk friction scheme under diff erent load and speed. Based on the experiment, a mathematical model was developed. In addition, grey relational analysis, a multi response optimization method, was used to determine optimal parameters. The uniqueness of this method is that it is used to evaluate the performance of various complex systems with insuffi cient information. The following are the conclusions drawn from the study: ● The study of PLA material obtained by FDM with diff erent printing orientation shows that horizontally printed pins have less wear than vertically printed ones. The greatest wear is characteristic of pins printed at an angle of 45°. ● It is noted that wear is signifi cantly aff ected by speed followed by load. This is also confi rmed by higher exponent values for speed and followed by load. A noticeable increase in wear is observed at higher process parameters. ● The PLA specimen printed by FDM with a printing orientation angle of 0° (PO1) exhibit less wear followed by specimen with printing orientation angle of 90° (PO3). This is mainly due to the high layer bonds strength along the printing orientation for PO1. The specimen with a printing orientation angle of 45° (PO2) exhibit poor wear resistance due to thermal softening. The optimal parameters for PO1 are found to be 600 N load and 451 rpm, which was determined using the multi variable grey relational analysis method. ● In the developed experimental mathematical model, the correlation coeffi cient (R2) is found to be 0.9244, 0.928 and 0.95 for PO1, PO2 and PO3. These models can be used to predict the wear of FDM printed PLA material in a friction pair with SS 316 stainless steel. ● The results of the study will be useful in 3D printing PLA biomaterial for hip joint application. References 1. Ventola C.L. Medical applications for 3D printing: current and projected uses. Pharmacy and Therapeutics Journal: Peer Review, 2014, vol. 39 (10), pp. 704–711. 2. Gibson I., Rosen D., Stucker B. Direct digital manufacturing. Additive Manufacturing Technologies. 2nd ed. New York, Springer, 2015, pp. 375–397. DOI: 10.1007/978-1-4939-2113-3_16. 3. Patil N.A., Njuguna J., Kandasubramanian B. UHMWPE for biomedical applications: performance and functionalization. European Polymer Journal, 2020, vol. 125, p. 09529. DOI: 10.1016/j.eurpolymj.2020.109529. 4. Kurtz S.M. Primer on UHMWPE. UHMWPE biomaterials handbook: ultra-high molecular weight polyethylene in total joint replacement and medical. 3rd ed. Amsterdam, Elsevier, 2016, pp. 1–6. 5. Lewis G. Properties of crosslinked ultra-high-molecular-weight polyethylene. Biomaterials, 2001, vol. 22 (4), pp. 371–401. DOI: 10.1016/S0142-9612(00)00195-2. 6. Wang A., Essner A., Polineni V., Stark C., Dumbleton J. Lubrication and wear of ultra-high molecular weight polyethylene in total joint replacements. Tribology International, 1998, vol. 31, pp. 17–33. DOI: 10.1016/S0301679X (98)00005-X. 7. Yousuf J.M., Mohsin A.A. Enhancing wear rate of high-density polyethylene (HDPE) by adding ceramic particles to propose an option for artifi cial hip joint liner. IOP Conference Series: Materials Science and Engineering, 2019, vol. 561, p. 012071. DOI: 10.1088/1757-899X/561/1/012071. 8. Orishimo K.F., Claus A.M., Sychterz C.J., Engh C.A. Relationship between polyethylene wear and osteolysis in hips with a second-generation porous-coated cementless cup after seven years of follow-up. The Journal of Bone & Joint Surgery, 2003, vol. 85 (6), pp. 1095–1099. DOI: 10.2106/00004623-200306000-00018.
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