Purpose

The purpose of this study is to investigate the influences of extruder temperatures and raster orientations on the mechanical properties of polylactic-acid (PLA) material processed by using fused filament fabrication (FFF).

Design/methodology/approach

In this research, the PLA specimens were first printed with nozzle or extruder temperatures of 205°C, 215°C and 225°C and then evaluated in terms of their physical, chemical and mechanical properties. An appropriate extruder temperature was then selected based on this experiment and used for the printing of the other PLA specimens having various raster orientations. A series of tensile tests were carried out again to investigate the influence of raster orientations on the tensile strength, tensile strain and elastic modulus of those FFF-processed PLA materials. In the end, the one-way ANOVA was applied for the statistical analysis and the Mohr’s circle was established to aid in the analysis of the data obtained in this experiment.

Findings

The result of this study shows that the chemistry, porosity, degree of crystallinity and mechanical properties (tensile strength, strain and elastic modulus) of the PLA material printed with a raster angle of 0° were all insensitive to the increasing extruder temperature from 205°C to 225°C. Meanwhile, the mechanical properties of such printed PLA material were obviously influenced by its raster orientation. In this case, a PLA material with a raster orientation parallel to its loading axis, i.e. those with a raster angle of θ = 0°, was found as the strongest material. Meanwhile, the raster configuration-oriented perpendicular to its loading axis or θ = 90° yielded the weakest PLA material. The results of the tensile tests for the PLA material printed with bidirectional raster orientations, i.e. θ = 0°/90° and 45°/−45° demonstrated their strengths with values falling between those of the materials having unidirectional raster θ = 0° and 90°. Furthermore, the result of the analysis by using a well-known Mohr’s circle confirmed the experimental tensile strengths and the failure mechanisms of the PLA material that had been printed with various raster orientations.

Originality/value

This study presented consistent results on the chemistry, physical, degree of crystallinity and mechanical properties of the FFF-processed PLA in responding to the increasing extruder temperature from 205°C to 225°C applied during the printing process. Unlike the results of the previous studies, all these properties were also found to be insensitive to the increase of extruder temperature. Also, the result of this research demonstrates the usability of Mohr’s circle in the analysis of stresses working on an FFF-processed PLA material in responding to the changes in raster orientation printed in this material.

中文翻译：

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挤出机温度和光栅取向对 FFF 加工的聚乳酸 (PLA) 材料机械性能的影响

目的

本研究的目的是研究挤出机温度和光栅取向对使用熔融长丝制造 (FFF) 加工的聚乳酸 (PLA) 材料的机械性能的影响。

设计/方法/方法

在这项研究中，PLA 样品首先在 205°C、215°C 和 225°C 的喷嘴或挤出机温度下打印，然后评估它们的物理、化学和机械性能。然后根据该实验选择合适的挤出机温度，并用于印刷具有各种光栅取向的其他 PLA 样品。再次进行了一系列拉伸试验，以研究光栅取向对那些 FFF 加工的 PLA 材料的拉伸强度、拉伸应变和弹性模量的影响。最后，将单向方差分析应用于统计分析，并建立莫尔圆以帮助分析本实验中获得的数据。

调查结果

这项研究的结果表明，以 0° 光栅角打印的 PLA 材料的化学性质、孔隙率、结晶度和机械性能（拉伸强度、应变和弹性模量）都对从 205° 升高的挤出机温度不敏感C 至 225°C。同时，这种印刷PLA材料的机械性能明显受到其光栅取向的影响。在这种情况下，光栅方向平行于其加载轴的 PLA 材料，即光栅角为θ = 0°的 PLA 材料被认为是最强的材料。同时，光栅配置取向垂直于其加载轴或θ= 90° 产生最弱的 PLA 材料。PLA 材料的拉伸试验结果表明，它们的强度介于具有单向光栅θ = 0° 和θ = 0°/90° 和 45°/−45° 90°。此外，使用众所周知的莫尔圆的分析结果证实了实验拉伸强度和 PLA 材料的失效机制，这些材料以各种光栅方向印刷。

原创性/价值

该研究在 FFF 加工的 PLA 的化学、物理、结晶度和机械性能方面给出了一致的结果，以响应印刷过程中挤出机温度从 205°C 增加到 225°C。与之前研究的结果不同，所有这些特性也被发现对挤出机温度的增加不敏感。此外，这项研究的结果证明了莫尔圆在分析 FFF 处理的 PLA 材料上的应力时的可用性，以响应该材料中印刷的光栅方向的变化。