![]() Other researchers have followed these criteria/rules closely. Have many features of a “real” part (e.g., thin walls, flat surfaces, holes, etc.). Finally, a strategy for standardizing a test artifact for performance characterization of AM systems is discussed. Results obtained from building the proposed artifact on several AM systems are discussed. Details of the design of a test artifact for AM intended for standardization are presented before discussing the measurements taken on the test artifact. ![]() A review of existing test artifacts used to characterize AM systems and technologies that are reported in the literature follows. These rules are drawn from existing literature as well as experience in working with test artifacts for different technologies. First, “rules” for test artifacts are discussed. This document details NIST efforts in developing a test artifact for AM. The standard test artifact can serve as a method for performance verification between system users and vendors, as well as provide a platform for vendors to demonstrate improvements in their AM systems. Additionally, if designed properly, the standard test artifact can test the limitations of the system. The clear benefit of a standard artifact is that different systems that produce the same standard artifact can be easily compared. The primary purpose of a test artifact is to quantitatively evaluate the performance of a system. However, the advantages of test artifacts are that producing parts is directly aligned with the actual purpose of the system and specialized measuring equipment is typically not necessary since the required equipment is common for discrete part manufacturing. The disadvantage of composite tests is that linking specific part errors to specific system error sources is often difficult. Manufacturing a test artifact enables a composite test since most errors in the system combine to contribute to errors in the part. While research and development of measurement methods for direct characterization of AM machines is ongoing, the better approach for performance characterization, at least in the short term, is through test artifacts. This is often difficult or impossible with AM systems, either because the moving components are not accessible to the end user or safety controls for potential hazards (e.g., high-power lasers) prevent the user from operating the system with the measuring instruments in the way. The former requires positioning and/or control of individual machine components (e.g., an x-axis slide) and measuring instruments mounted in and around the machine’s work volume to measure relative positions, orientations, velocities, etc. In manufacturing metrology, two primary approaches exist to evaluate the performance of a system: (1) through a series of direct measurements of system components or characteristics, and (2) through measurements of manufactured test artifact. However, the need for better understanding of the technologies through system performance characterization is universal. A system encompasses both the machine and the process.Īdditive manufacturing research at the National Institute of Standards and Technology 1 (NIST) focuses on metal-based AM (primarily laser-based PBF) because parts produced by these technologies are likely to be used as functional components, have a higher inherent value than parts made from other materials, and require further improvements before widespread acceptance of metal-based AM can be achieved. The processing parameters are the inputs to the machine that govern the process (e.g., laser power in laser sintering). For example, the process in laser sintering involves the laser beam melting a specific section of a powder bed, fusing particles together to form a part. The process is the physics involved in producing the part. For the purposes of this paper, a machine is defined as the physical structure comprising its components and their motions along with any computer software controlling those motions. There are many different AM technologies-for example, stereolithography, laser sintering, multi-jet printing, etc.-the ASTM International standard terminology document for AM groups these technologies into seven different process categories: binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion (PBF), sheet lamination, and vat photopolymerization. Additive manufacturing (AM)-also known as additive fabrication, 3D printing, direct part manufacturing, layered manufacturing, and freeform fabrication-is defined as the process of joining materials to make objects from three-dimensional (3D) model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies such as machining.
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