Microsoft Word - ETASR_V12_N5_pp9329-9335 Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9329 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur Gear Stiffness Dragos Gabriel Zisopol Mechanical Engineering Department Petroleum- Gas University Ploiesti, Romania zisopol@zisopol.ro Dragos Valentin Iacob Production Department Marelli Ploiesti, Romania dragoshicb@gmail.com Alexandra-Ileana Portoaca Mechanical Engineering Department Petroleum – Gas University Ploiesti, Romania alexandra.portoaca@upg-ploiesti.ro Received: 6 July 2022 | Revised: 24 July 2022 and 7 August 2022 | Accepted: 15 August 2022 Abstract-This paper studies the influence of FDM (Fused Depositing Modeling) parameters on gear stiffness made of Polylactic Acid (PLA). 3D printing parameters must be optimized because they influence the physical, mechanical, and quality characteristics of the additive manufactured part along with its functionality. The objective of this research is to optimize FDM parameters in order to obtain the highest stiffness. In this context, we used Finite Element Analysis (FEA) and we made experimental tests to validate its results. The experimental tests are divided into two categories, gears with the same parameters and gears with the same layer height and variable filling percentage. The average results of gear stiffness with the same parameters are 8.18% highest than the average results of gear stiffness with the same layer height and variable filling percentages. Keywords–3D printing; FDM parameters; FDM parameters; stiffness; spur gears; FEA I. INTRODUCTION The term additive manufacturing encompasses a set of technologies and processes that use different materials to make objects by depositing material in successive layers. Due to the recent improvements in additive technologies, they are used in many fields of activity. Initially, they were suitable for rapid prototyping of models, now they are used for sophisticated applications such as unique parts, custom products, medical implants, etc. [1-4]. Compared to formative and subtractive manufacturing, additive manufacturing technologies have many advantages: material waste is negligible, realization of very complex objects without bases and fasteners, cost- effective manufacturing, simplicity in use, etc. [5, 6]. In this paper we show that FDM 3D printing with PLA can be a good solution for plastic gears and we also find the optimal parameters for FDM printed gears. The novelty of this article consists in determining the influence of FDM parameters, the height of the deposited PLA layer, and the percentage of filling for spur gears with straight teeth, on the rigidity gear assembly. The rigidity of PLA gear assembly, 3D-printed by FDM, is theoretically determined using FEA and experimentally validated using a device designed and manufactured by the authors, whereas the recording of the results was realized by a digital torque wrench [7, 9]. II. FDM 3D PRINTING OF SPUR GEARS PLA filament with a diameter of 1.75mm, Verbatim brand, was the material used for FDM 3D printing of the spur gears with straight teeth. The printing methodology is shown in Figure 1. Fig. 1. Study methodology. 2D and later 3D models of straight-tooth cylindrical gears were made in the CAD Solidworks program. Figure 2 shows the 2D model of the drive gear module 1 with 30 straight teeths (R1) and Figure 3 shows the 2D model of the drive wheel module 1 with 60 straight teeth (R2). Both were designed in Solidworks. Using the same software, the two CAD files corresponding to the 3D models obtained were saved with the STL extension. Corresponding author: Dragoș Valentin Iacob Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9330 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... Fig. 2. Leading spur gear (R1). Fig. 3. Driven spur gear (R2). Using the Creality Slicer program of the Creality CR-X printer, the two files with the STL extension corresponding to the straight-tooth cylindrical gears shown in Figures 2 and 3, after entering the 3D printing parameters, were transformed into a G-file Code (Figure 4). Fig. 4. G-Code commands. The parameters of 3D printing of cylindrical gears, presented in Table I, are grouped in two categories, constant process parameters and variable technological parameters. The first parameters category refers to the orientation of the parts, the printing speed (Vp), the extruder temperature (Te), the printing bed temperature (Tp), and the model used for filling. Variable technological parameters refer to the height of the deposited layer (Hs) and the percentage of filling, (Pu) [1]. Also, the number of gear pairs tested is mentioned. Data in Table I were used to reveal constant parameters and parameters varied to test different layer thicknesses and infill percentages. TABLE I. 3D PRINTING PARAMETERS Constant parameters Variable parameters Spur gears Building orientation X, Y Extrusion temperature (Te) – 210 °C Bed temperature (Tp) – 60 °C Speed (Vp) – 80 mm/s Filling model – Lines 45° Layer hight (Hs) Infill percentage (Pu) R1 R2 (mm) (%) (pieces) 0.10 5 0 7 5 1 00 27 0.15 27 0.20 27 Figure 5 shows the set of cylindrical gears with straight teeth R1 and R2, created with the Creality Slicer [3]. The G- Code file was transferred to the Creality CR-X printer on which 162 straight-tooth cylindrical gears were made of PLA (81 R1 and 81 R2), according to the data centralized in Table I. Fig. 5. R1 and R2 spur gears, in Creality Slicer. III. STIFFNESS DETERMINATION OF THE 3D PRINTED SPUR GEAR The stiffness of the PLA 3D printed spur gears was theoretically determined using FEA applied in Solidworks 2016 and experimentally validated using the device in Figure 8 designed and manufactured by the authors. A. Theorethical Study For FEA of stiffness gears with straight in Solidworks 2016 a torque R1 equal to 0.0022kN· m was applied (minimum value at which teeth yielded). The FEA results of the stiffness of the straight-tooth cylindrical gears of PLA (R1 and R2) are shown in Figures 5 and 6. The equivalent Von Mises stress obtained is 2.225MPa and the maximum linear displacement is 1.208mm. Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9331 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... Fig. 6. Equivalent Von Mises stress. Fig. 7. Maximum linear displacement. B. Experimental Tests For the experimental determination of the gear stiffness of the gears, the authors designed and made the device shown in Figure 8. Fig. 8. Gear stiffness determination device: 1 – leading gear (R1); 2 – washer; 3 – driven wheel (R2); 4– locking rod; 5 – digital torque wrench. The stiffness of the leading gear R1 (1), fixed to the device by the washer (2) and locked by the rod (4), with the driven gear R2 (3) was determined by the digital torque wrench (5) by recording the maximum torque corresponding to the gear assembly failure. A total of 162 experimental tests were performed on the device in Figure 8, using cylindrical gears with straight teeth with the parameters shown in Table I. C. Results and Discussion The results obtained from the experimental determinations performed on the device in Figure 8 are shown graphically in Figures 9-36. The averages of the results obtained from the experimental determinations; are presented in Figure 36. Fig. 9. Gear stiffness R1 (Hs = 0.10mm, Pu = 100%) with R2 (Hs = 0.10mm, Pu = 100%). Fig. 10. Gear stiffness R1 (Hs = 0.10mm, Pu = 75%) with R2 (Hs = 0.10mm, Pu = 75%). Fig. 11. Gear stiffness R1 (Hs = 0.10mm, Pu = 50%) with R2 (Hs = 0.10.mm, Pu = 50%). Fig. 12. Gear stiffness R1 (Hs = 0.15mm, Pu = 100%) with R2 (Hs = 0.15mm, Pu = 100%). Fig. 13. Gear stiffness R1 (Hs = 0.15mm, Pu = 75%) with R2 (Hs = 0.15mm, Pu = 75%). 0.0240 0.0206 0.0196 0.0172 0.0202 0.0193 0.0100 0.0200 0.0300 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. 0.0182 0.0191 0.0195 0.0189 0.0193 0.0189 0.0170 0.0180 0.0190 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0175 0.0220 0.0203 0.0198 0.0172 0.0206 0.0000 0.0100 0.0200 0.0300 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. 0.0183 0.0182 0.0205 0.0177 0.0203 0.0186 0.0160 0.0180 0.0200 0.0220 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. 0.0215 0.0217 0.0189 0.0170 0.0181 0.0173 0.0150 0.0200 0.0250 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9332 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... Fig. 14. Gear stiffness R1 (Hs = 0.15mm, Pu = 50%) with R2 (Hs = 0.15mm, Pu = 50%). Fig. 15. Gear stiffness R1 (Hs = 0.20mm, Pu = 100%) with R2 (Hs = 0.20mm, Pu = 100%). Fig. 16. Gear stiffness R1 (Hs = 0.20mm, Pu = 75%) with R2 (Hs = 0.20mm, Pu = 75%). Fig. 17. Gear stiffness R1 (Hs = 0.20mm, Pu = 50%) with R2 (Hs = 0.20mm, Pu = 50%). Fig. 18. Gear stiffness R1 (Hs = 0.10mm, Pu = 100%) with R2 (Hs = 0.10mm, Pu = 75%). Fig. 19. Gear stiffness R1 (Hs = 0.10mm, Pu = 100%) with R2 (Hs = 0.10mm, Pu = 50%). Fig. 20. Gear stiffness R1 (Hs = 0.10mm, Gu = 75%) with R2 (Hs = 0.10mm, Pu = 100%). Fig. 21. Gear stiffness R1 (Hs = 0.10mm, Pu = 75%) with R2 (Hs = 0.10mm, Pu = 50%). Fig. 22. Gear stiffness R1 (Hs = 0.10mm, Pu = 50%) with R2 (Hs = 0.10mm, Pu = 100%). Fig. 23. Gear stiffness R1 (Hs = 0.10mm, Pu = 50%) with R2 (Hs = 0.10mm, Pu = 75%). 0.0183 0.0185 0.0169 0.0191 0.0180 0.0168 0.014 0.016 0.018 0.020 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. 0.0197 0.0199 0.0213 0.0190 0.0191 0.0190 0.0160 0.0180 0.0200 0.0220 1 2 3 4 5 6 S ti ff n e ss k N ·m Test No. 0.0183 0.0181 0.0161 0.0182 0.0181 0.0184 0.0140 0.0160 0.0180 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0202 0.0182 0.0183 0.0170 0.0187 0.0178 0.0140 0.0160 0.0180 0.0200 0.0220 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0170 0.0169 0.0172 0.0161 0.0186 0.0160 0.0140 0.0160 0.0180 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0174 0.0174 0.0174 0.0146 0.0154 0.0174 0.0120 0.0140 0.0160 0.0180 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0194 0.0153 0.0157 0.0145 0.0189 0.0167 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0135 0.0187 0.0172 0.0149 0.0177 0.0183 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0177 0.0187 0.0197 0.0169 0.0171 0.0183 0.0140 0.0160 0.0180 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0173 0.0193 0.0160 0.0175 0.0170 0.0153 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9333 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... Fig. 24. Gear stiffness R1 (Hs = 0.15mm, Pu = 100%) with R2 (Hs = 0.15mm, Pu = 75%). Fig. 25. Gear stiffness R1 (Hs = 0.15mm, Pu = 100%) with R2 (Hs = 0.15mm, Pu = 50%). Fig. 26. Gear stiffness R1 (Hs = 0.15mm, Pu = 75%) with R2 (Hs = 0.15mm, Pu = 100%). Fig. 27. Gear stiffness R1 (Hs = 0.15mm, Pu = 75%) with R2 (Hs = 0.15mm, Pu = 50%). Fig. 28. Gear stiffness R1 (Hs = 0.15mm, Pu = 50%) with R2 (Hs = 0.15mm, Pu = 100%). Fig. 29. Gear stiffness R1 (Hs = 0.15mm, Pu = 50%) with R2 (Hs = 0.15mm, Pu = 75%). Fig. 30. Gear stiffness R1 (Hs = 0.20mm, Pu = 100%) with R2 (Hs = 0.15mm, Pu = 75%). Fig. 31. Gear stiffness R1 (Hs = 0.20mm, Pu = 100%) withR2 (Hs = 0.15mm, Pu = 50%). Fig. 32. Gear stiffness R1 (Hs = 0.20mm, Pu = 75%) with R2 (Hs = 0.15mm, Pu = 100%). Fig. 33. Gear stiffness R1 (Hs = 0.20mm, Pu = 75%) with R2 (Hs = 0.15mm, Pu = 50%). 0.0179 0.0173 0.0177 0.0151 0.0145 0.0177 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0168 0.0165 0.0189 0.0146 0.0170 0.0163 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0171 0.0177 0.0180 0.0170 0.0176 0.0164 0.0150 0.0160 0.0170 0.0180 0.0190 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0197 0.0137 0.0195 0.0173 0.0192 0.0151 0.0100 0.0150 0.0200 0.0250 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0177 0.0168 0.0182 0.0168 0.0194 0.0158 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0188 0.0157 0.0132 0.0187 0.0191 0.0153 0.0100 0.0150 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0186 0.0190 0.0196 0.0181 0.0205 0.0146 0.0100 0.0150 0.0200 0.0250 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0160 0.0180 0.0187 0.0176 0.0170 0.0167 0.0140 0.0160 0.0180 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0220 0.0162 0.0212 0.0178 0.0208 0.0185 0.0100 0.0150 0.0200 0.0250 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0176 0.0176 0.0183 0.0183 0.0190 0.0176 0.0160 0.0170 0.0180 0.0190 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9329-9335 9334 www.etasr.com Zisopol et al.: A Theoretical-Experimental Study of the Influence of FDM Parameters on PLA Spur... Fig. 34. Gear stiffness R1 (Hs = 0.20mm, Pu = 50%) with R2 (Hs = 0.15mm, Pu = 100%). Fig. 35. Gear stiffness R1 (Hs = 0.20mm, Pu = 50%) with R2 (Hs = 0.15mm, Pu = 75%). Fig. 36. Average stiffness of the R1 and R2 gear assembly. The rigidity of the assembly of cylindrical gears was theoretically determined using FEA in Solidworks and experimentally validated using the device shown in Figure 8. The theoretical study of the gears stiffness revealed results that are presented in Figures 6 and 7, validated by the experimental results presented in Figures 9-36. It was found out that the percentage difference was 9.49%. Analyzing the results of the 162 experimental tests, an average value of the stiffness of the cylindrical gears with straight teeth 0.01791kN· m was obtained. For cylindrical gears, the minimum value of gear stiffness is 0.01323kN· m and was obtained for the gear with R1 (Hs = 0.15mm, Pu = 50%) and R2 (Hs = 0.15mm, Pu = 75%) and the maximum value of the gear stiffness is 0.02402kN· m and was obtained for the gear with R1 (Hs = 0.10mm, Pu = 100%) and R2 (Hs = 0.10mm, Pu = 100%). The height of the deposited layer (Hs) and the percentage of filling (Pu) influence the stiffness of the cylindrical gears assembly with straight teeth. Increasing the height of the deposited layer from Hs = 0.10mm to Hs = 0.15mm increases the stiffness of the gear by 2.34% and increasing from Hs = 0.10mm to Hs = 0.20mm increases stiffness by 4.02%. The increase of the filling percentage from Pu = 50% to Pu = 75% increases gear stiffness by 0.08% and the increase from Pu = 50% to Pu = 100% by 4.84%. The rigidity of the gears assembly with straight teeth is influenced by the percentage of filling (Pu) by 5.44% more than it is influenced by the height of the deposited layer (Hs). The novelty of this work consists in obtaining results of the maximum torque that can be applied to various printed gears characterized by different layer thicknesses and infill percentages until it deforms irreversibly in order to protect the energy source used in practical applications. There is a limited number of studies conducted on the subject. In [10], 6 types of PLA, from different producers, 2 types of ABS and 3 types of nylon all printed with the same parameters were compared and an optimal type of PLA that crushed at 0.018kN· m torque was. IV. CONCLUSIONS The objective of the current study was to determine an optimal combination of gear characterization by the printing and tested parameters. Furthermore, the result is similar to other studies using different PLA producers [10], so the study is considered valid. The paper reveals the maximum torque supported by 3D printed PLA (with certain parameters) and helps in choosing efficient variants of construction depending of the requirements of the application. The study is recommended to be applied to other types of 3D printed gears from various materials, using different additive manufacturing technologies. REFERENCES [1] D. G. Zisopol, I. Nae, A. I. Portoaca, and I. Ramadan, "A Theoretical and Experimental Research on the Influence of FDM Parameters on Tensile Strength and Hardness of Parts Made of Polylactic Acid," Engineering, Technology & Applied Science Research, vol. 11, no. 4, pp. 7458–7463, Aug. 2021, https://doi.org/10.48084/etasr.4311. [2] D. G. Zisopol, I. Nae, A. I. Portoaca, and I. 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Ramadan, "A Comparative Analysis of the Mechanical Properties of Annealed PLA," Engineering, Technology & Applied Science Research, vol. 12, no. 4, pp. 8978–8981, Aug. 2022, https://doi.org/10.48084/etasr.5123. 0.0169 0.0169 0.0185 0.0179 0.0188 0.0185 0.0150 0.0160 0.0170 0.0180 0.0190 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.0164 0.0171 0.0184 0.0178 0.0183 0.0180 0.0140 0.0160 0.0180 0.0200 1 2 3 4 5 6S ti ff n e ss k N ·m Test No. 0.02014 0.01898 0.01958 0.01893 0.01907 0.01794 0.01965 0.01787 0.01835 0.01696 0.01660 0.01676 0.01671 0.01806 0.01707 0.01670 0.01669 0.01729 0.01741 0.01744 0.01679 0.01840 0.01731 0.01941 0.01805 0.01791 0.01766 0.00000 0.00500 0.01000 0.01500 0.02000 0.02500 0,1- 100% 0,1- 100% 0,1- 75% 0,1- 75% 0,1- 50% 0,1- 50% 0,15- 100% 0,15- 100% 0,15- 75% 0,15- 75% 0,15- 50% 0,15- 50% 0,20- 100% 0,20- 100% 0,20- 75% 0,20- 75% 0,20- 50% 0,20- 50% 0,1- 100% 0,1- 75% 0,1- 100% 0,1- 50% 0,1- 75% 0,1- 100% 0,1- 75% 0,1- 50% 0,1- 50% 0,1- 100% 0,1- 50% 0,1- 75% 0,15- 100% 0,15- 75% 0,15- 100% 0,15- 50% 0,15- 75% 0,15- 100% 0,15- 75% 0,15- 50% 0,15- 50% 0,15- 100% 0,15- 50% 0,15- 75% 0,2- 100% 0,2- 75% 0,2- 100% 0,2- 50% 0,2- 75% 0,2- 100% 0,2- 75% 0,2- 50% 0,2- 50% 0,2- 100% 0,2- 50% 0,2- 75% Average stiffness of the gear assembley R1 and R2 (kN·m) R 1 [ H l (m m ) - P i (% )] ; R 2 [ H l (m m ) - P i (% )] . 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