Additive manufacturing processes have the potential to produce near-net shaped complex final parts in various industries such as aerospace, medicine, or automotive. Powder bed based and nozzle based processes like laser metal deposition (LMD), laser powder bed fusion (LPBF), and electron beam melting (EBM) are commercially available, but selecting the most suitable process for a specific application remains difficult and mainly depends on the individual know-how within a certain company. Factors such as the material used, part dimension, geometrical features, as well as tolerance requirements contribute to the overall manufacturing costs that need to be economically reasonable compared to conventional processes. Within this contribution, the quantitative analysis of basic geometrical features such as cylinders, thin walls, holes, and cooling channels of a special designed benchmark demonstrator manufactured by LMD; LPBF and EBM are presented to compare the geometrical accuracy within and between these processes to verify existing guidelines, connect the part quality to the process parameters, and demonstrate process-specific limitations. The fabricated specimens are investigated in a comprehensive manner with 3D laser scanning and CT scanning with regard to dimensional and geometrical accuracy of outer and inner features. The obtained results will be discussed and achievable as-built tolerances for assessed demonstrator parts will be classified according to general tolerance classes described [DIN ISO 2768-1, Allgemeintoleranzen—Teil 1: Toleranzen fur Langen- und Winkelmase ohne einzelne Toleranzeintragung (1991). Accessed 26 February 2018; DIN ISO 2768-2, Allgemeintoleranzen—Teil 2: Toleranzen fur Form und Lage ohne einzelne Toleranzeintragung (1991). Accessed 26 February 2018].

中文翻译：

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基于粉末床和基于喷嘴的增材制造工艺的尺寸精度和公差比较

增材制造工艺有可能在航空航天、医药或汽车等各个行业生产近净形状的复杂最终零件。基于粉末床和基于喷嘴的工艺，如激光金属沉积 (LMD)、激光粉末床融合 (LPBF) 和电子束熔化 (EBM) 已在商业上可用，但为特定应用选择最合适的工艺仍然很困难，主要取决于特定公司内的个人专有技术。所用材料、零件尺寸、几何特征以及公差要求等因素都会影响整体制造成本，与传统工艺相比，这些成本需要在经济上合理。在此贡献范围内，对基本几何特征（例如圆柱、薄壁、孔、LMD制造的特殊设计的基准演示器的冷却通道；LPBF 和 EBM 用于比较这些过程内部和之间的几何精度，以验证现有指南，将零件质量与过程参数联系起来，并证明特定于过程的限制。使用 3D 激光扫描和 CT 扫描对制造的样品进行全面研究，以了解外部和内部特征的尺寸和几何精度。将讨论获得的结果，并根据所描述的一般公差等级对评估的演示器零件可实现的竣工公差进行分类 [DIN ISO 2768-1, Allgemeintoleranzen-Teil 1: Toleranzen fur Langen- und Winkelmase ohne einzelne Toleranzeintragung (1991)。2018 年 2 月 26 日访问；DIN ISO 2768-2, Allgemeintoleranzen—Teil 2: Toleranzen fur Form und Lage ohne einzelne Toleranzeintragung (1991)。2018 年 2 月 26 日访问]。