Background

Fused filament fabrication (FFF) introduces anisotropic material properties to the final parts, which includes minimum interlayer values. In this study, ASTM D638 type I specimens are 3D printed from acrylonitrile butadiene styrene (ABS) in the upright build direction and their tensile properties are evaluated.

Objective

Higher nozzle temperature outside the narrow section is proposed to improve tensile properties and move the breakage location towards the specimen center. Time spent above the glass transition temperature in the specimens is suggested as an indicator of their local strength.

Methods

An enclosure is built for a LulzBot Taz 6 desktop 3D printer that allows thermal imaging without interference from the environment. Temperature and humidity inside and outside the enclosure, and specimen mass are recorded. An automation script is developed to extract the temperature history of the deposited layers during 3D printing along the specimens.

Results

Optimum cross-sectional pattern for maximum tensile properties is the one with all walls and no infill. Nozzle temperature is varied from 220 to 260 °C in 10 °C increments and 231 °C is found as optimum for highest tensile properties. Using the optimum nozzle temperature of 231 °C in the narrow section, and a higher temperature of 261 °C in the grip sections and transition areas moves the breakage location towards the specimen center.

Conclusions

Time spent above the glass transition temperature agrees well with breakage location of the specimens. The impact of humidity on tensile properties is found to be more pronounced than the specimen mass.

中文翻译：

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可变喷嘴温度和横截面图案对 3D 打印 ABS 样品的层间拉伸强度的影响

背景

熔丝制造 (FFF) 为最终部件引入了各向异性材料特性，其中包括最小夹层值。在本研究中，ASTM D638 I 型试样由丙烯腈丁二烯苯乙烯 (ABS) 沿垂直构建方向 3D 打印，并评估了它们的拉伸性能。

客观的

建议在狭窄部分外提高喷嘴温度以提高拉伸性能并将断裂位置移向试样中心。建议在试样中超过玻璃化转变温度的时间作为其局部强度的指标。

方法

外壳专为 LulzBot Taz 6 桌面 3D 打印机打造，可在不受环境干扰的情况下进行热成像。记录外壳内外的温度和湿度以及试样质量。开发了一个自动化脚本来提取沿样本进行 3D 打印期间沉积层的温度历史。

结果

具有最大拉伸性能的最佳横截面图案是具有所有壁且无填充物的横截面图案。喷嘴温度在 220 到 260 °C 之间以 10 °C 的增量变化，231 °C 被认为是最高拉伸性能的最佳温度。在狭窄部分使用 231 °C 的最佳喷嘴温度，在夹持部分和过渡区域使用 261 °C 的更高温度，将断裂位置移向试样中心。

结论

高于玻璃化转变温度的时间与样品的断裂位置非常吻合。发现湿度对拉伸性能的影响比试样质量更显着。