光固化列印中尺寸效應對機械性質探討

Abstract

3D列印技術的廣泛應用，除了與傳統製程相比更能有效節省材料，對細節精密度更高，從大型物件到極小的微結構，甚至有奈米尺度列印技術出現，應用到許多精密機械元件中，其結構的完整性以及機械性質更顯得重要。 本研究嘗試使用光固化列印技術(Vat Photopolymerization)中的LCD(Liquid Crystal Display)列印技術，探討在3D列印中的尺寸效應，微觀尺寸效應探討樹脂的微結構，透過列印參數設定的改變，包括曝光時間、切層厚度。也改變了試片的尺寸，進行尺寸效應探討。並使用萬能材料試驗機(MTS)及自行架設的微型拉伸試驗器進行拉伸試驗，對成品試片的機械性質表現以及尺寸誤差進行討論。 經由拉伸試驗的結果分析發現，從微觀結構來看，較久的曝光時間給予樹脂足夠的能量產生固化反應，擁有較高的強度。較薄的切層厚度，除了改善列印垂直方向的解析度，重疊的曝光對於成品結構也有強化，有著較高的強度。而尺寸效應則顯示，在小尺度情況下，強度會下降。 總體來說本研究希望探討列印參數以及列印尺度對材料機械性質的關聯性，可以提供未來在小尺度的3D列印中，對於材料強度的評估，適當的列印參數有助於改善整體的外觀以及強度。

With the widespread application of 3D printing technology, it has proven to be more material-efficient and capable of producing finer details compared to traditional manufacturing methods. From large-scale objects to extremely small microstructures—down to the nanoscale—3D printing has found applications in many mechanical components, where structural integrity and mechanical properties are important. This study investigates the size effect in 3D printing using the LCD (Liquid Crystal Display) method, a type of vat photopolymerization technology. The investigation focuses on the microscale size effect by examining the microstructure of the resin, through adjustments in printing parameters such as exposure time and layer thickness. Specimen dimensions were also varied to analyze macroscopic size effects. Mechanical properties and dimensional deviations of the printed samples were evaluated using a universal testing machine (MTS) and a custom-built micro tensile testing device. Tensile test results show that, from a microstructural perspective, longer exposure times provide the resin with sufficient energy to initiate curing reactions, resulting in higher strength. Thinner layer thicknesses not only improve vertical resolution but also enhance the structural strength by increasing interlayer overlap, leading to higher mechanical performance. Regarding size effects, it was observed that the strength decreased at smaller scales. Overall, this study aims to explore the relationship between printing parameters, printing scale, and the mechanical properties of materials. The findings can contribute to strength evaluation and optimization of printing settings in future applications of small-scale 3D printing, ultimately improving both structural appearance and strength.