来自University of Nantes最近发表了一项研究，研究了FFF 3D打印中层之间的传热和粘附。为了理解，建模和实际量化印刷过程中的热交换，研究人员着手找到最佳的打印参数集，以最大程度地利用3D打印零件中的机械性能。
FFF与注入成型
With today’s technology, the difference between FFF and injection molding is like night and day. While 3D printing does offer a great deal of design freedom, the porosities in the parts and the poor adhesion between the thermoplastic layers mean FFF printed parts simply can’t take as much force as injected parts.
The adhesion between the layers is predominantly determined by the temperature of the nozzle during extrusion. Too low, and the adhesion is weak. Too high, and the polymer starts to decompose, resulting in low viscosity and a subsequent structural collapse. The Nantes researchers – seeking that ‘sweet spot’ – believed diving deep and investigating the heat transfer at each stage of the process would lead them there.
他们最初构建的假定传热的预测数值模型发生在印刷过程中的许多点。这包括从喷嘴到聚合物的热量，从聚合物到空气的对流电流，聚合物层之间的热交换，构建板的热量，从聚合物到空气的辐射损失以及放热结晶而导致的热损失。
The influence of heat transfer on adhesion
Throughout the experiment, the team used aCreality CR-103D打印机，带有ABS和碳纤维增强的Pekk。选择作为测试样品的3D模型非常基本，因为它可以轻松地应用传热模型。热控制的长凳和外壳用于帮助进行精确的温度测量。温度测量本身是使用红外摄像头和高温计进行的。一旦进行了实验测量，团队将它们与他们先前开发的预测数值模型进行了比较。
The researchers concluded that their numerical model was sufficiently correct in predicting the heat transfer during the printing process as the results fell in line with the physical measurements. Despite this, their “poor knowledge of the rheological properties” stopped them from being able to accurately predict the adhesion between the layers – at least quantitatively. The team explained that their next steps would be to study the coalescence evolution of the polymers to be able to predict the formation of macro-porosities. This would make the “global degree of adhesion calculable”, giving insight into the process parameters necessary to produce high-performance parts.
Further details of the study can be found in the paper titled ‘Heat Transfer and Adhesion Study for the FFF Additive Manufacturing Process’。它由Arthur Lepoivre，Nicolas Boyard，Arthur Levy和Vincent Sobotka合着。
While printing temperature is a key player, it is not the only factor that can have a major effect on the strength of a 3D printed part. A recent study by researchers in Greece调查了ABS细丝的变化响应回收的机械性能。有趣的是，该小组发现，ABS的稳定性和总体强度提高到第五周期，此后化学降解开始产生。在其他地方，美国陆军尝试了细丝添加剂，开发了一个高强度的细丝ABS壳和星形聚碳酸酯芯。
The nominations for the2020 3D Printing Industry Awards现在打开。您认为谁应该成为今年演出的入围名单？现在有你的发言权。
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特征图显示了实验中的IR成像。通过南特大学的图像。
