A quantitative, image-based analysis of the spreading performance of PolyArylEtherKetone polymer powders during Powder Bed Fusion Additive Manufacture

Powder spreadability in the powder bed fusion process is normally visually assessed by the machine operator through repeat trials at room temperature or elevated temperatures. Some studies used powder rheology results as an indicator of the powder spreadability. This study presents a novel method of image-based analysis for the assessment of polymer spreading quality for powder bed fusion and demonstrates that the subjective assessment of the machine operator can be replaced by quantitative and measurable data. Twenty-four developmental grade PolyArylEtherKetone powders were tested. Images of the powder bed surface were analysed in MATLAB and the relationships with the powder rheology established through statistical analysis. The two methods for calculating surface deviations from variations in the greyscale images showed to be sensitive to the recoater travel and presented a strong correlation with the Normalised Aeration Sensitivity (NAS), a powder rheology parameter identified in a previous study as the most significant parameter able to categorise powder flow and spreadability based on a yes/no response.

在粉末床熔融工艺中，粉末的铺展性通常由机器操作员通过在室温或高温下的重复试验进行目视评估。一些研究将粉末流变学结果用作粉末铺展性的指标。本研究提出了一种基于图像分析的新方法，用于评估粉末床熔融的聚合物铺展质量，并证明机器操作员的主观评估可由定量和可测量的数据取代。对24种研发级聚芳醚酮粉末进行了测试。在MATLAB中对粉末床表面的图像进行了分析，并通过统计分析建立了与粉末流变学的关系。从灰度图像变化计算表面偏差的两种方法对铺粉器的移动很敏感，并且与归一化充气灵敏度（NAS）呈现出很强的相关性，NAS是先前研究中确定的一个粉末流变学参数，是能够根据是/否响应对粉末流动性和铺展性进行分类的最重要参数。