熱熔融層積製造方法於生物力學應用之可行性評估

Feasibility assessment of fused deposition modeling in biomechanical application

李明憲(Ming-Hsien Lee)

指導教授 ： 林鼎勝

義守大學/醫學科技學院/生物醫學工程學系/碩士(2022年)

摘要

積層製造(Additive Manufacturing)，俗稱3D列印(3D printing)，因為價格下降且普及率增加，開始嘗試將其應用於各領域當中，通常被強調為是一種小量生產、成本較低、客製化、快速原型和環保的技術。隨著在各領域中的蓬勃發展，3D列印此項技術也開始嘗試應用於醫療領域，各學者紛紛開始研究將3D列印應用在各種醫療器材製作中，但大多數侷限在初步運用，例如手術前規劃用模型或輔助導引器械，較少應用於植入物或是內、外固定器等醫材，其原因可能是受到醫療法規限制及製程有效性還有待驗證。本研究的目的為使用田口方法找出不同材料在使用熱熔融層積技術時的最佳加工參數並探討其力學性質。
　　本研究選用田口方法中的L18直交表將三種材料（PLA、Nylon 6和Nylon6+CF）及七種加工參數(層高、壁厚、填充率、填充樣式、列印溫度、熱床溫度和列印速度)進行搭配並透過拉伸實驗求得勁度（Stiffness），計算訊噪比以評估各加工參數對於力學性質之影響，以利評估材料於後續開發應用之可能性。
　　使用田口方法可以獲得各材料的最佳加工參數組合，其中PLA材料為層高0.3 mm、壁厚4.8 mm、填充率75%、三-六角形填充樣式、列印溫度210 ℃、熱床溫度60 ℃及25 mm/s的列印速度；Nylon 6材料為層高0.15 mm、壁厚4.8 mm、填充率75%、三角形填充樣式、列印溫度275 ℃、熱床溫度70 ℃及25 mm/s的列印速度；Nylon 6+CF材料為層高0.15 mm、壁厚4.8 mm、填充率75%、三-六角形填充樣式、列印溫度255 ℃、熱床溫度90 ℃及75 mm/s的列印速度。由材料拉伸實驗結果可以獲得以下力學性質，PLA最大位移量為5.90 mm、所能承受的最大負載為2260.65 N、最大拉伸應力為49.08 MPa、楊氏係數為1195.20 MPa、勁度為383.16 N/mm；Nylon 6最大位移量為8.49 mm、所能承受的最大負載為1522.18 N、應力為34.94 MPa、楊氏係數為807.20 MPa、勁度為179.68 N/mm；Nylon 6+CF最大位移量為6.47 mm、所能承受的最大負載為2227.69 N、應力為49.23 MPa、楊氏係數為1239.00 MPa、勁度為346.14 N/mm。
　　從結果可以得知，對PLA力學強度影響最大的是壁厚、層高兩種加工參數，以本研究之結果推論，設定層高為0.3 mm、壁厚為4.8 mm、填充率為75%、三-六角形填充樣式、列印溫度為210 ℃、熱床溫度為60 ℃及25 mm/s的列印速度是最適合之工作參數；NYLON 6需注意填充樣式、填充率兩種加工參數，此兩種對於力學強度影響最大，而其餘五種加工參數對於力學強度也有一定程度的影響，以本研究之結果推論，設定層高為0.15 mm、壁厚為4.8 mm、填充率為75%、三角形填充樣式、列印溫度為275 ℃、熱床溫度為70 ℃及25 mm/s的列印速度，是最適合之工作參數；對NYLON6+CF力學強度影響最大的是層高、壁厚兩種加工參數，而列印速度的影響最小，以本研究之結果推論，層高0.15 mm、壁厚4.8 mm、填充率75%、三-六角形填充樣式、列印溫度255 ℃、熱床溫度90 ℃及75 mm/s的列印速度為最適合之工作參數，且加入碳纖維的尼龍材料可以使力學強度接近PLA，但同時也保留部分延展性，故在後續應用上，NYLON 6 + CF有較大的應用空間。

關鍵字

3D列印 ； 積層製造 ； 碳纖維 ； 生物力學 ； 熱熔融層積

並列摘要

Owing to the reducing prices and the increasing penetration rate, additive manufacturing (AM), also known as 3D printing, has expanded its application to various fields. It is a small volume production, low cost, easy to customize, rapid prototyping and environmental-friendly technology. With the vigorous development in numerous industries, the application of AM technology in the medical field has established. Many studies tried to adapt 3D printing technology for the production of various medical equipment. However, most of these studies are limited to preclinical applications, such as a model for preoperative planning, surgical guide developing and medical education. Nevertheless, it is seldom used in implants or traumatic fixators due to the restriction of medical regulations. Moreover, the AM process still needed further verification and validation. Therefore, the purpose of this study is to find out the optimal AM process parameters of different materials in Fused Deposition Modeling (FDM) to obtain the optimal mechanical characteristics.
　　In this study, the L18(21 x 36) orthogonal table of the Taguchi method was used for three different materials (PLA, Nylon 6 and Nylon6+CF) and seven process parameters (layer height, wall thickness, filling rate, filling pattern, printing temperature, hot bed temperature and column temperature) of FDM process. Stiffness was obtained through tensile testing and the signal-to-noise ratio was calculated to evaluate the influence of various process parameters. Optimal parameters were acquired for three materials of FDM process.
　　The optimal process parameters of PLA was that the layer height of 0.3 mm, wall thickness of 4.8 mm, infill density of 75%, tri-hexagonal infill pattern, printing temperature of 210℃, build plate temperature of 60℃, and print speed of 25 mm/s; the optimal process parameters of nylon 6 were that the layer height of 0.15 mm, wall thickness of 4.8 mm, infill density of 75%, triangular infill pattern, printing temperature of 275°C, build plate temperature of 70°C, and print speed of 25 mm/s; the optimal process parameters of nylon 6+CF were that the layer height of 0.15 mm, wall thickness of 4.8 mm, infill density of 75%, tri-hexagonal infill pattern, printing temperature of 255°C, build plate temperature of 90°C, and print speed of 75 mm/s. For PLA material, the results of tensile test showed that the maximum displacement and load are 5.90 mm and 2260.65 N, tensile stress is 49.08 MPa, the Young's modulus is 1195.20 MPa and the stiffness is 383.16 N/mm; for Nylon 6 material, the results revealed that the maximum displacement and load are 8.49 mm and 1522.18N, tensile stress is 34.94 MPa, Young's modulus is 807.20 MPa and stiffness is 179.68 N/mm; for Nylon 6+CF material, the results depicted that the maximum displacement and load are 6.47 mm and 2227.69 N, tensile stress is 49.23 MPa, Young's modulus is 1239.00 MPa and stiffness is 346.14 N/mm.
　　From the results of mechanical test and Taguchi analysis, we could conclude that wall thickness and layer height had the significant influence on the mechanical strength of PLA material. For Nylon 6 material, infill pattern and infill density were the significant process parameters while the other parameters have affective influences on mechanical strength. In addition, NYLON6+CF, layer height and wall thickness had the greatest influence on the mechanical strength but the print speed has the least influence. The nylon material with carbon fiber could compensate the mechanical strength which would be close to PLA, but also retain the ductility of nylon. From the findings of this study, we might infer that NYLON 6 + CF would be suitable for various applications.

並列關鍵字

3D printing ； additive manufacturing ； carbon fiber ； biomechanics ； Fused Deposition Modeling (FDM)

參考文獻

[1] D. Sher. "Wohlers Report 2019 details striking range of developments in AM worldwide." https://tinyurl.com/2bll4kuj (accessed.

[2] "Wohlers Report: 3D Printing Industry Grew 7.5% in 2020." https://tinyurl.com/25gbxcwz (accessed.

[3] "Wohlers Report 2022 Finds Strong Industry-Wide Growth." https://tinyurl.com/2b3d3y3s (accessed.

[4] 徐勤禎. "印出未來新商機: 3D列印醫用新浪潮." https://tinyurl.com/26q5r9lx (accessed.

[5] 徐. A. Hsu). "印出未來新商機: 3D列印醫用新浪潮(Technology, Applications and Trends of Medical 3D Printing Market)." https://tinyurl.com/24pz9p85 (accessed.