Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography.
Loose powder detection and surface characterization in selective laser sintering via optical coherence tomography.
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DOI：
10.1098/rspa.2016.0201
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发表时间：
2016-07
期刊：
影响因子：
--
通讯作者：
Clare AT
中科院分区：
文献类型：
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作者：
Guan G;Hirsch M;Syam WP;Leach RK;Huang Z;Clare AT
选择性激光烧结（SLS）过程中产生的缺陷在构建完成后很难在不使用基于X射线的方法的情况下进行非破坏性检测。通过逐层评估完整性来克服这个问题已经成为SLS设备的用户非常感兴趣的领域。在本研究中使用光学相干断层扫描（OCT）检测表面纹理和次表面粉末，未熔化/未充分烧结，已知是部件完整性差的常见原因，并将阻止在应用程序要求保证无缺陷部件的情况下使用SLS。为了证明仪器和相关数据处理算法的能力，样品被构建为具有分级孔隙，其被嵌入在完全致密的区域中以模拟有缺陷的区域。然后将模拟的原位测量与用于产生可变密度区域的工艺参数相关联。使用这种方法，可以检测松散的粉末，并在大约300 μm的次表面深度处区分±5%的密度。为了证明OCT作为一种表面轮廓技术的价值，表面纹理数据集与焦点变化显微镜进行了比较。在空间带宽匹配过程之后，获得了类似的结果。
Defects produced during selective laser sintering (SLS) are difficult to non-destructively detect after build completion without the use of X-ray-based methods. Overcoming this issue by assessing integrity on a layer-by-layer basis has become an area of significant interest for users of SLS apparatus. Optical coherence tomography (OCT) is used in this study to detect surface texture and sub-surface powder, which is un-melted/insufficiently sintered, is known to be a common cause of poor part integrity and would prevent the use of SLS where applications dictate assurance of defect-free parts. To demonstrate the capability of the instrument and associated data-processing algorithms, samples were built with graduated porosities which were embedded in fully dense regions in order to simulate defective regions. Simulated in situ measurements were then correlated with the process parameters used to generate variable density regions. Using this method, it is possible to detect loose powder and differentiate between densities of ±5% at a sub-surface depth of approximately 300 μm. In order to demonstrate the value of OCT as a surface-profiling technique, surface texture datasets are compared with focus variation microscopy. Comparable results are achieved after a spatial bandwidth- matching procedure.