Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No. 2, November 2023, pp. 96-105 96 DOI: 10.17977/um016v7i22023p096 Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength Using Analysis of Variance Faqih Fadillah1, Heru Suryanto2*, and Suprayitno1 1Master Program of Mechanical Engineering, Faculty of Engineering, Universitas Negeri Malang, Jl. Semarang 5 Malang, East Java, Indonesia 2Centre of Advanced Material and Renewable Energy, Universitas Negeri Malang, Jl. Semarang No. 5, Malang, 65145, Indonesia *Corresponding emails: heru.suryanto.ft@um.ac.id Article history: Received: 8 January 2023 / Received in revised form: 22 March 2023 / Accepted: 30 March 2023 Available online 31 July 2023 ABSTRACT Fused deposition modeling of 3D printing is the process of making workpieces or parts by adding filaments to each layer. Some indicators of a high-quality product of 3D printing are the precisions dimensions, the surface roughness, and tensile strength. This research aims to find the parameters most affecting surface roughness and tensile strength. The research design used an experimental method with input parameters: (1) print speed (15-35 mm/s), (2) print temperature (200-210C), (3) layer height (0.1 – 0.3 mm), (4) infill line directions (0-90), and dependent variables were surface roughness and tensile strength. The data distribution used the L9 orthogonal array, and the statistic analysis used ANOVA. Material uses nanographite-reinforced polylactic acid (PLA) filament. The results indicate that print parameters that significantly affect surface roughness are layer height and infill line directions. The best surface roughness on the layer height parameter is 0.1 mm, and the infill line directions parameter is 90. Based on ANOVA analysis, print speed, print temperature, and layer height do not significantly affect tensile strength, but infill line directions significantly affect tensile strength. The best tensile strength on infill line directions is 90. The best average tensile strength with nanographite-reinforced PLA filament is 38.56 N/mm2, with 35 m/s print speed, 205 C print temperature, 0.1 mm layer height, and 90 infill line direction parameter. The best average surface roughness with nanographite-reinforced PLA filament is 0.66 µm, with 35 m/s print speed, 205 C print temperature, 0.1 mm layer height, and 90 infill line direction parameter. Copyright © 2023. Journal of Mechanical Engineering Science and Technology. Keywords: 3D print, ANOVA, nanographite, polylactic acid filament, roughness, tensile strength I. Introduction The flow chart of making a product generally consists of ideas, designs, prototypes, performance tests, and implementation. Prototypes aim to evaluate the products before they are implemented and manufactured in mass production. Prototypes are made in small quantities so that the additive manufacturing process is prioritized over other manufacturing processes. Additive manufacturing is efficient and effective for small amounts of products [1]. In addition, creating complex models using additive manufacturing can eliminate jigs and fixtures. Additive manufacturing has several types, one of which is FDM (fused deposition modeling). Type FDM of additive manufacturing is the process of making workpieces or parts by adding filaments to each layer. Additive manufacture is appropriate if applied to 97 Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No.2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) prototypes that make the manufacture of varied parts and small quantities. Additive manufacturing has a cheaper and more consistent process price. As an illustration, additive manufacturing can make parts cheaper than injection molding processes in the range of 4000 to 12000 parts with a production cost of 2.1 €/part, in injection molding cheaper with parts above 12000 with a production price range below 2 €/part [2]. Additive manufacturing does not require a longer process. Additive manufacturing can make a simple process so that it requires two methods (raw material and component manufacturing), compared to traditional manufacturing, which requires three methods (raw materials, part manufacturing, and assembly parts). Besides that, in making parts, it is necessary to combine several machines for complicated shapes [2]. Two hundred million users predicted in 2026, 3D printing is predicted to grow from 18% to 32% (2018 to 2026) with USD 7-23 billion to USD 51.77 billion [3]. Factors affecting the print result are the material, machine, and setting parameters. The quality of 3D print objects is affected by setting parameters, setting the distance of the reference point, and choosing a filament with the appropriate adhesion [4]. Setting parameters of 3D printing greatly affects print quality. The lower layer height has an impact on increasing tensile strength, smoothness, and dimensional accuracy of 3D print objects, but affects the long print time [5]. Some parameters like print speed (PS) and print temperature (PT) need to be tested. Surface roughness and topography are the main parameters that indicate the accuracy of components. However, the average surface roughness (Ra) of arithmetic samples made by material extrusion varies between 9 and 40 μm, which can be categorized as poor surface roughness [6]. Layer height (LH) or thickness affects the surface quality and dimensions of the workpiece more than other parameters such as PS and PT [7]. In previous studies, researchers discussed the effect of PS, PT, and LH on surface roughness. It is necessary to show the contribution of print speed, printing temperature, layer thickness, and infill line directions to the tensile strength and surface roughness. The goal of this research is to find the parameters that most affect surface roughness and tensile strength. II. Material and Methods This research was an experimental study, experimental data distribution used L9 (33) orthogonal arrays. Statistical analysis used the analysis of variance (ANOVA). The ANOVA method was utilized to understand the percentage of contribution of each parameter. ANOVA analysis was used to find the critical factor for a specified response [8]. In this research, data distribution used L9 (33) orthogonal arrays because it was more cost-effective than the full factorial method [9]. Variable independent and dependent is shown in Figure 1, and the level of the dependent variable is shown in Table 1. Fig. 1. Independent variables and dependent variables ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology 98 Vol. 7, No. 2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) Table 1. Variables and data distribution Variables Code Unit Variations Print Speed PS mm/s 15 25 35 Printing Temperature PT C 200 205 210 Layer Height LH mm 0.1 0.2 0.3 Infill Line Directions ILD  0 45 90 The object of this study was the ASTM D638 Type IV specimen with PLA material. The design of the L9 (34) orthogonal array with three replications as shown in Table 2. Table 2. Design of experiment L9 orthogonal array No PS PT LH ILD PS PT LH ILD 1 -1 -1 -1 -1 15 mm/s 200 C 0.1 mm 0 2 -1 0 0 0 15 mm/s 205 C 0.2 mm 45 3 -1 1 1 1 15 mm/s 210 C 0.3 mm 90 4 0 -1 0 1 25 mm/s 200 C 0.2 mm 90 5 0 0 1 -1 25 mm/s 205 C 0.3 mm 0 6 0 1 -1 0 25 mm/s 210 C 0.1 mm 45 7 1 -1 1 0 35 mm/s 200 C 0.3 mm 45 8 1 0 -1 1 35 mm/s 205 C 0.1 mm 90 9 1 1 0 -1 35 mm/s 210 C 0.2 mm 0 The study used nanographite-reinforced polylactic acid (PLA) filament with the specifications as shown in Table 3. The print process uses a 3D printer (Creality Ender 3 Prusa i3) with a diameter of a single nozzle is 0.4 mm. Table 3. Characteristic of nanographite-reinforced PLA filament for 3D Print Print temp. (C) 190 – 210 Tensile strength (N/mm 2 ) 33.8 Bed temp. (C) No Heat/(60—80) Elongation at break (%) 10.39 Density (g/cm 3 ) 1.09 Modulus young (N/mm 2 ) 3.4 The surface roughness (Ra) was measured in a Surftest SJ-310 Series (Mitutoyo, Japan), and the tensile strength test was conducted in JTM-UTS210 Computer Servo Universal Testing Machine (2T) using the standard of ASTM D638 Type IV [10] as shown in Figure 2. The statistical analysis used in this study was a three-way ANOVA (three-lane ANOVA). A three-lane ANOVA is used to test the mean differences of three or more sample groups with three independent variables and one dependent variable. In this study, ANOVA analysis used Minitab software. The hypotheses of this study are: H0 = there is no difference between the average n groups. H1 = there is a difference between the average n groups. The interpretation of c is: 99 Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No.2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) If the p-value is less than α = 0.05, so H1 is accepted, or H0 is rejected If the p-value is more than α = 0.05, so H0 is accepted, or H1 is rejected Fig. 2. Tensile test specimen ASTM D638 type IV If the test results show H0 (no difference), then the follow-up test (Post Hoc Test) is not carried out. On the other hand, if the test results show H1 (there is a difference), then a further test (Post Hoc Test) must be carried out. III. Results and Discussions The data of roughness and tensile strength of 3D-printed product is shown in Table 4. Table 4. Roughness and tensile strength of the 3D-printed product Run Roughness (Ra) Tensile strength (N/mm 2 ) 1 2 3 1 2 3 1 3.21 6.44 4.97 31.17 26.56 22.48 2 9.78 14.09 10.63 35.71 35.39 24.37 3 3.21 2.31 2.24 31.95 27.46 31.71 4 1.60 6.24 5.08 30.29 38.69 33.87 5 18.91 12.56 18.60 30.34 25.00 26.93 6 2.01 2.34 14.91 31.35 35.92 40.99 7 18.26 10.85 22.72 24.91 20.46 28.66 8 1.09 0.52 0.36 38.26 35.58 41.84 9 7.85 26.38 33.10 32.29 26.61 32.48 Analysis of Surface Roughness ANOVA analysis of the surface roughness of 3D-printed product is shown in Table 5. Table 5. ANOVA analysis results for surface roughness of the 3D-printed product Source DF Adj SS Adj MS F-Value P-Value PS 2 232.72 116.358 3.64 0.047 PT 2 12.47 6.237 0.19 0.825 LH 2 433.30 216.649 6.77 0.006 ILD 2 723.68 361.840 11.31 0.001 Error 18 575.93 31.996 Total 26 1978.10 ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology 100 Vol. 7, No. 2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) The interpretation of data from the ANOVA results is shown in Table 6. Table 6. Interpretation of ANOVA results for average surface roughness of the 3D-printed product Source P-Value Decision Interpretation PS 0.047 < 0.05 H0 is rejected There is a difference in average surface roughness at a PS of 15; 25, and 35mm/s. PT 0.825 > 0.05 H0 is accepted There is no difference in average surface roughness at PT of 200; 205, and 210C LH 0.006 < 0.05 H0 is rejected There is a difference in average surface roughness on LH of 0.1 mm, 0.2 mm, 0.3 mm ILD 0.001 < 0.05 H0 is rejected There is a difference in the average surface roughness in ILD of 0, 45, 90. The analysis results in Table 6 show that the 3D printing parameter variables (PS, PT, LH, and ILD) that affect the surface roughness of 3D-printed product is the PS and LH [11] and ILD. From the summary model obtained R-Square by 70.88 %, this means that the value of the influence of PS, PT, LH, and ILD on surface topology is 70.88% while other variables influence the remaining 29.12%. The grouping information results are shown in Table 7, and the simultant test results using the Tukey test are shown in Table 8. They show that PS of 15 mm/s, LH of 0.1 mm, and ILD of 90 have a small average value, so that is a smooth surface. Table 7. Grouping information using the Tukey method and 95% confidence PS LH ILD PS N Mean Grouping LH N Mean Grouping ILD N Mean Grouping 35 mm/s 9 13.46 A 0.2 mm 9 12.75 A 0 9 14.67 A 25 mm/s 9 9.14 A B 0.3 mm 9 12.18 A 45 9 11.73 A 15 mm/s 9 6.32 B 0.1 mm 9 3.98 B 90 9 2.51 B Table 8. Tukey simultaneous tests for differences means PS LH ILD Difference of levels Difference of means Adj P-value Difference of levels Difference of means Adj P-value Difference of levels Difference of means Adj P-value 25 - 15 mm/s 2.82 0.552 0.2 - 0.1 mm 8.77 0.011 45 - 0 -2.94 0.526 35 - 15 mm/s 7.14 0.039 0.3 - 0.1 mm 8.20 0.017 90 - 0 -12.15 0.001 35 - 25 mm/s 4.32 0.263 0.3 - 0.2 mm -0.57 0.976 90 - 45 -9.22 0.008 Table 9 indicates that PS of 15 mm/s have a difference with PS of 35 mm/s; LH of 0.1 mm has a difference with LH of 0.2 mm and 0.3 mm; ILD of 90 have a difference with LH of 0 and 45. 101 Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No.2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) Table 9. Interprestasi data Tukey simultaneous for surface roughness of the 3D-printed product Difference of Levels Adjusted P-Value Decision Interpretation Print Speed 25 - 15 mm/s 0.552>0.05 H0 Accepted there isn’t a difference between PS 25 and 15 mm/s 35 - 15 mm/s 0.039<0.05 H0 Rejected there is a difference between PS 35 and 15 mm/s 35 - 25 mm/s 0.263>0.05 H0 Accepted there isn’t a difference between PS 35 and 25 mm/s Layer Height 0.2 - 0.1 mm 0.011<0.05 H0 Rejected there is a difference between LH 0.2 and 0.1 mm 0.3 - 0.1 mm 0.017<0.05 H0 Rejected there is a difference between LH 0.3 and 0.1 mm 0.3 - 0.2 mm 0.976>0.05 H0 Accepted there isn’t a difference between LH 0.3 and 0.2 mm Infill Line Directions 45 - 0 0.526>0.05 H0 Accepted there isn’t a difference between ILD 45 and 0 90 - 0 0.001<0.05 H0 Rejected there is a difference between ILD 90 and 0 90 - 45 0.008>0.05 H0 Rejected there is a difference between ILD 90 and 45 Figure 3 show the grouping of LH with topographic results. 0 1000 2000 3000 4000 -60 -40 -20 0 20 40 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 1 st parameter 6 th parameter 8 th parameter 0 1000 2000 3000 4000 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 2 nd parameter 4 th parameter 9 th parameter (a) (b) 0 1000 2000 3000 4000 -60 -40 -20 0 20 40 60 s u rf a c e t o p o g ra p h y ( µ m ) measurement length (µm) 3 rd parameter 5 th parameter 7 th parameter (c) Fig. 3. Topographic graph with LH of (a) 0.1 mm; (b) 0.2 mm; (c) 0.3 mm. ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology 102 Vol. 7, No. 2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) Based on Figure 3, LH of 0.1 mm has a better surface than LH of 0.2 mm and 0.3 mm. LH of 0.1 mm has a good surface because each print has a small height, so the nozzle output is also small and the result smoother. The smaller the print height, the better the results obtained, but the longer the printing time. The LH, followed by the nozzle diameter, are the process parameters that greatly influence the arithmetical mean height (Ra) [12]. Analysis of Tensile Strength The result of ANOVA of tensile strength of the 3D-printed product is shown in Table 10. Table 10. ANOVA analysis results for tensile strength of the 3D-printed product Source DF Adj SS Adj MS F-Value P-Value PS 2 39.32 19.66 1.16 0.337 PT 2 91.13 45.57 2.68 0.096 LH 2 193.14 96.57 5.68 0.012 ILD 2 174.10 87.05 5.12 0.017 Error 18 306.29 17.02 Total 26 803.99 The interpretation of data from the ANOVA results is shown in Table 11. From the summary model, it is obtained R-Square by 61.90%. This means that the value of the influence of print speed (PS), print temperature (PT), layer height (LH), and infill line direction (ILD) on tensile strength (Y) is 61.90% while other variables influence the remaining 38.1%. Table 11. Interpretation of the ANOVA analysis for tensile strength data of 3D-printed product Source P-Value Decision Interpretation PS 0.337 > 0.05 H0 Accepted There is no difference in tensile strength at PS of 15; 25, and 35 mm/s PT 0.096 > 0.05 H0 Accepted There is no difference in tensile strength at PT of 200; 205, and 210 C LH 0.012 < 0.05 H0 Rejected There is a difference in tensile strength at print layer heights 0.1; 0.2, and 0.3 mm ILD 0.017 < 0.05 H0 Rejected There is a difference in tensile strength at print infill line directions 0; 45 and 90 Based on ANOVA analysis, PS and PT have no significant effect on tensile strength. Other variables influence based on the remaining R-square (38.1%). Other possible influencing variables, such as material and filament diameter, need to be investigated. Based on ANOVA Analysis, layer height (LH) and infill line direction (ILD) significantly affect tensile strength. 3D printing type FDM has the best tensile strength at the 90-angle print (parallel to the tensile axis) and has poor tensile strength when the print angle is below 50 [13]. 3D Print of FDM makes shapes by adding layer by layer with a pattern like arranging fibers, therefore the best tensile strength is a tensile force that is parallel with the fibers. 103 Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No.2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) (a) (b) Fig. 4. (a) Force and displacement of the 3D-printed specimen; (b) Nanographite-reinforced PLA filament The force and displacement graph of a 3D-printed product using ASTM D638 type IV is shown in Figure 4. The graph shows the material printed from PLA has brittle properties, different from PLA as raw material that have ductile properties. The average tensile strength of nanographite-reinforced PLA filaments is 34.705 N/mm2. Nanographite-reinforced PLA filaments more strong than PLA filaments with 13.22 N/mm2 [14]. The ultimate tensile strength decreases as the printing angle becomes smaller or the layer becomes thicker. This theoretical model and experimental method can also be applied to other 3D printing materials fabricated by FDM or SLA techniques [15]. The tensile test of PLA with the ASTM D638 specimen results shows that parts printed at a raster angle of 0° exhibit higher tensile strength than parts printed at a raster angle of 90° [16]. The tensile test was performed to measure the effect of different raster angles, layer height, and raster width [16]. IV. Conclusions The four dependent variables (print speed, print temperature, layer height, and infill line direction) that have a significant effect on surface roughness are print speed, layer height, and infill line direction. From the follow-up Post Hoc Test, the most superior parameter of print speed, layer height, and infill line direction are 15 mm/s, 0.1 mm, and 90, respectively, which indicates the highest level of surface smoothness. Based on ANOVA analysis, print speed (PS) and print temperature (PT) have no significant effect on tensile strength. Successively the effect of prints speed (PS), print temperature (PT), layer height (LH), and infill line direction (ILD) on tensile strength, as seen from the p-value, is 0.47; 0.825; 0.006; and 0,001, respectively. In the future, this nanocomposite filament can be applied to product which needs better surface finishing. Acknowledgment The authors would like to appreciate the Universitas Negeri Malang, which provides the facilities to conduct the research and DRTPM through the research grant scheme PPS-PTM with contract number of 20.6.88/UN32.20.1/LT/2023. 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0 20 40 60 80 100 F o rc e ( K g f) Displacement (mm) 1 2 3 4 5 6 7 8 9 3D Print ASTM D638 Type IV tensile test specimens 0 1 2 0 10 F o rc e ( K g f) Displacement (mm) 1 2 3 4 Nanographite-reinforced polylactic acid filaments ISSN: 2580-0817 Journal of Mechanical Engineering Science and Technology 104 Vol. 7, No. 2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) References [1] S. Farah, D. G. Anderson, and R. Langer, “Physical and mechanical properties of PLA, and their functions in widespread applications — A comprehensive review,” Adv. Drug Deliv. Rev., vol. 107, pp. 367–392, 2016, doi: 10.1016/j.addr.2016.06.012. [2] D. S. Thomas and S. W. Gilbert, “Costs and cost effectiveness of additive manufacturing: A literature review and discussion,” Gaithersburg (USA): National Institute of Standards and Technology, pp. 1–96, 2015. [3] S. Wickramasinghe, T. Do, and P. Tran, “FDM-Based 3D printing of polymer and associated composite: A review on mechanical properties, defects and treatments,” Polymers (Basel)., vol. 12, no. 7, pp. 1–42, 2020, doi: 10.3390/polym12071529. [4] H. Wu and T. T. Chen, “Quality control problems in 3D printing manufacturing : A review,” Rapid Prototyp. J., vol. 24, no. 3, pp. 607-614, 2018, doi: 10.1108/RPJ-02- 2017-0031. [5] G. Percoco, L. Arleo, G. Stano, and F. Bottiglione, “Analytical model to predict the extrusion force as a function of the layer height, in extrusion based 3D printing,” Addit. Manuf., vol. 38, no. July 2020, 2021, doi: 10.1016/j.addma.2020.101791. [6] R. I. Campbell, M. Martorelli, and H. S. Lee, “Surface roughness visualisation for rapid prototyping models,” CAD Comput. Aided Des., vol. 34, no. 10, pp. 717–725, 2002, doi: 10.1016/S0010-4485(01)00201-9. [7] E. Taşcıoğlu, Ö. Kıtay, A. Ö. Keskin, and Y. Kaynak, “Effect of printing parameters and post‑process on surface roughness and dimensional deviation of PLA parts fabricated by extrusion‑based 3D printing,” J. Brazilian Soc. Mech. Sci. Eng., vol. 44, p. 139, 2022, doi: https://doi.org/10.1007/s40430-022-03429-7. [8] G. K. Sharma, A. K. Johar, T. B. Kumar, and D. Boolchandani, “Effectiveness of Taguchi and ANOVA in design of differential ring oscillator,” Analog Integr. Circuits Signal Process., vol. 104, no. 3, pp. 331–341, 2020, doi: 10.1007/s10470- 020-01671-4. [9] K. V. Sabarish, J. Baskar, and P. Paul, “Overview on L9 taguchi optimizational method,” Int. J. Adv. Res. Eng. Technol., vol. 10, no. 2, pp. 652–658, 2019, doi: 10.34218/IJARET.10.2.2019.062. [10] S. Anand Kumar and Y. Shivraj Narayan, Tensile testing and evaluation of 3D- printed PLA specimens as per ASTM D638 type IV standard, no. February 2018. Springer Singapore, 2019. [11] D. Taqdissillah, A. Z. Muttaqin, M. Darsin, D. Dwilaksana, and N. Ilminnafik, “The Effect of Nozzle Temperature, Infill Geometry, Layer Height and Fan Speed on Roughness Surface in PETG Filament,” J. Mech. Eng. Sci. Technol., vol. 6, no. 2, p. 74, 2022, doi: 10.17977/um016v6i22022p074. [12] I. Buj-Corral, X. Sánchez-Casas, and C. J. Luis-Pérez, “Analysis of am parameters on surface roughness obtained in PLA parts printed with FFF technology,” Polymers (Basel)., vol. 13, no. 14, pp. 1–20, 2021, doi: 10.3390/polym13142384. [13] T. Yao, J. Ye, Z. Deng, K. Zhang, Y. Ma, and H. Ouyang, “Tensile failure strength and separation angle of FDM 3D printing PLA material: Experimental and theoretical analyses,” Compos. Part B Eng., vol. 188, no. November 2019, p. 107894, 2020, doi: 10.1016/j.compositesb.2020.107894. [14] M. Syaifuddin and H. Suryanto, “The Effect of Multi-Extrusion Process of Polylactic Acid on Tensile Strength and Fracture Morphology of Filament Product,” J. Mech. Eng. Sci. Technol., vol. 5, no. 1, pp. 62–72, 2021, doi: 10.17977/um016v5i12021p06. [15] T. Yao, Z. Deng, K. Zhang, and S. Li, “A method to predict the ultimate tensile 105 Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 Vol. 7, No.2, November 2023, pp. 96-105 Fadillah et al. (Study on Effect of 3D Printing Parameters on Surface Roughness and Tensile Strength) strength of 3D printing polylactic acid (PLA) materials with different printing orientations,” Compos. Part B Eng., vol. 163, no. July 2018, pp. 393–402, 2019, doi: 10.1016/j.compositesb.2019.01.025. [16] S. R. Rajpurohit and H. K. Dave, “Analysis of tensile strength of a fused filament fabricated PLA part using an open-source 3D printer,” Int. J. Adv. Manuf. Technol., vol. 101, pp. 1525–1536, 2019, doi: https://doi.org/10.1007/s00170-018-3047-x.