Development of an Additive Manufactured Artifact to Characterize Unfused Powder Using Computed Tomography
Development of an Additive Manufactured Artifact to Characterize Unfused Powder Using Computed Tomography
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开发一种增材制造的制品，利用计算机断层扫描来表征未熔化的粉末
DOI：
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发表时间：
2020
影响因子：
1.1
通讯作者：
R. Racasan
中科院分区：
文献类型：
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作者：
A. Tawfik;Paul Bills;L. Blunt;R. Racasan
相加制造(AM)被认为是生产高价值部件的核心技术。生产复杂的和单独修改的部件以及原型，使加法制造比传统的减法加工具有实质性的优势。对于大多数行业来说，目前实施AM的一些障碍包括缺乏构建的可重复性和缺乏质量保证标准。部件的机械性能关键取决于所获得的密度。因此，必须进行缺陷/孔隙率分析，以验证部件的完整性和可行性。在使用AM生产的零件中，使用计算机断层扫描检测未熔融粉末是具有挑战性的，因为检测依赖于密度的差异。这项研究提出了一种使用计算机断层扫描来区分添加剂制造部件中未熔化粉末和空隙的优化方法。检测未熔化的粉末需要检测颗粒之间的空洞。以前的研究发现，检测未熔融的粉末需要体素尺寸小至4μm~3。对于大多数应用，由于部件大小、扫描时间长和数据分析，使用较小体素大小的扫描是不合理的。在这项研究中，使用不同的体素大小来比较扫描所需的时间，并通过数据分析来展示体素大小对检测微小缺陷的影响。所用粉末为Ti6Al4V，其粒度为45-100μm，通常用于Arcam电子束熔炼机。文物由一个6毫米的圆棒组成，其内部特征从50μm到1400μm不等，包含空隙和未熔化粉末的混合物。使用变焦显微镜对缺陷的直径和深度进行表征，然后使用尼康XTH2 25工业CT进行扫描，以测量伪影并表征缺陷/气孔的内部特征。为了减少工艺变量的数量，测量参数如灯丝电流、加速电压、X射线滤光片材料和厚度保持不变。使用VGStudio Max 3.0(Volume Graphics，德国)软件包进行数据处理、表面测定和缺陷/孔隙率分析。这项研究的主要重点是探索最佳方法，以增强对气孔/缺陷的检测，同时最大限度地减少扫描、数据分析和确定噪声对分析的影响所需的时间。
Additive manufacturing (AM) is recognized as a core technology for producing high-value components. The production of complex and individually modified components, as well as prototypes, gives additive manufacturing a substantial advantage over conventional subtractive machining. For most industries, some of the current barriers to implementing AM include the lack of build repeatability and a deficit of quality assurance standards. The mechanical properties of the components depend critically on the density achieved. Therefore, defect/porosity analysis must be carried out to verify the components’ integrity and viability. In parts produced using AM, the detection of unfused powder using computed tomography is challenging because the detection relies on differences in density. This study presents an optimized methodology for differentiating between unfused powder and voids in additive manufactured components, using computed tomography. Detecting the unfused powder requires detecting the cavities between particles. Previous studies have found that the detection of unfused powder requires a voxel size that is as small as 4 μm3. For most applications, scanning using a small voxel size is not reasonable because of the part size, long scan time, and data analysis. In this study, different voxel sizes are used to compare the time required for scanning, and the data analysis showing the impact of voxel size on the detection of micro defects. The powder used was Ti6Al4V, which has a grain size of 45–100 μm, and is typically employed by Arcam electron beam melting (EBM) machines. The artifact consisted of a 6 mm round bar with designed internal features ranging from 50 μm to 1400 μm and containing a mixture of voids and unfused powder. The diameter and depth of the defects were characterized using a focus variation microscope, after which they were scanned using a Nikon XTH225 industrial CT to measure the artifacts and characterize the internal features for defects/pores. To reduce the number of the process variables, the measurement parameters, such as filament current, acceleration voltage, and X-ray filtering material and thickness were kept constant. The VGStudio MAX 3.0 (Volume Graphics, Germany) software package was used for data processing, surface determination, and defects/porosity analysis. The main focus of this study is to explore the optimal methods for enhancing the detection of pores/defects while minimizing the time taken for scanning, data analysis, and determining the effects of noise on the analysis.
影响因子：
9.1
作者：
Lambert, J.;Chambers, A. R.;Spearing, S. M.
通讯作者：
Spearing, S. M.
利用探测器滤波器降低 X 射线计算机断层扫描中的噪声，以检查增材制造金属零件的结构完整性
影响因子：
1
作者：
Tawfik A
通讯作者：
Tawfik A