Purpose

The purpose of this study is to evaluate and compare the mechanical performance of FFF parts when subjected to post processing thermal treatment. Therefore, a study of the annealing treatment influence on the mechanical properties was performed. For this, two different types of Nylon (PA12) were used, FX256 and CF15, being the second a short fibre reinforcement version of the first one.

Design/methodology/approach

In this study, tensile and flexural properties of specimens produced via FFF were determined after being annealed at temperatures of 135°C, 150°C or 165°C during 3, 6, 12 or 18 h and compared with the non-treated conditions. Differential scanning calorimetry (DSC) was performed to determine the degree of crystallinity. To evaluate the annealing parameters’ influence on the mechanical properties, a full factorial design of experiments was developed, followed by an analysis of variance, as well as post hoc comparisons, to determine the most significative intervening factors and their effect on the results.

Findings

The results indicate that CF15 increased its tensile modulus, strength, flexural modulus and flexural strength around 11%, while FX256 presented similar values for tensile properties, doubling for flexural results. Flexural strain presented an improvement, indicating an increased interlayer behaviour. Concerning to the DSC analysis, an increase in the degree of crystallinity for all the annealed parts.

Originality/value

Overall, the annealing treatment process cause a significant improvement in the mechanical performance of the material, with the exception of 165°C annealed specimens, in which a decrease of the mechanical properties was observed, resultant of material degradation.

中文翻译：

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退火对PA12和PA12纤维增强FFF印刷样品的机械性能的影响

目的

这项研究的目的是评估和比较FFF零件在进行后处理热处理时的机械性能。因此，进行了退火处理对机械性能的影响的研究。为此，使用了两种不同类型的尼龙（PA12），即FX256和CF15，第二种是第一种的短纤维增强版。

设计/方法/方法

在这项研究中，通过FFF生产的样品的拉伸和挠曲性能是在135°C，150°C或165°C的温度下经过3、6、12或18 h退火后确定的，并与未处理条件进行了比较。进行差示扫描量热法（DSC）以确定结晶度。为了评估退火参数对机械性能的影响，开发了完整的因子设计实验，然后进行方差分析以及事后比较，以确定最有意义的干预因素及其对结果的影响。

发现

结果表明，CF15的拉伸模量，强度，弯曲模量和弯曲强度提高了约11％，而FX256的拉伸性能值相似，弯曲结果翻了一番。弯曲应变表现出改善，表明层间行为增加。关于DSC分析，所有退火部件的结晶度增加。

创意/价值

总体而言，退火处理工艺可显着改善材料的机械性能，但165°C退火的试样除外，其中观察到机械性能下降，这是材料降解的结果。