1. Scope

Keywords

Rationale

This standard was adapted in ISO/ASTM format directly from the NASA LB-PBF specification MSFCSPEC3716. Only terminology and conventions have been changed from the original document that is meant to certify parts used in manned space flight produced by LB-PBF when enforced together with WKXXXXX-3717, Additive Manufacturing-Process Characteristics and Performance-Standard Specification for Control and Qualification of Laser Beam Powder Bed Fusion Processes. This Standard is published by ISO TC 261 ASTM F42 to provide uniform engineering and technical requirements for processes, procedures, practices, and methods that have been endorsed as standard for aerospace programs and projects, including requirements for selection, application, and design criteria of safety critical parts. Additive Manufacturing (AM) has begun to revolutionize much of the aerospace design and manufacturing paradigm. The process of building parts incrementally, layer by layer, reduces costs, enables new designs, and challenges the order of the traditional aerospace hardware development cycle. For existing designs, AM offers a unique ability to substantially reduce the cost of manufacturing complex hardware, particularly in the limited quantities common to spaceflight applications. For new designs, the high cost and lead time associated with production of complex development hardware by conventional processing have moved the industry to near-complete reliance on meticulous analysis to mitigate the programmatic impact of test failures. With the advent of AM processing, prototype hardware designs will be iterated with minimal cost and impact to schedule, restoring the role of systematic, incremental development testing for aerospace systems. The unique strengths of the AM process have motivated the spaceflight industry to lead in the application of AM technology. The greatest challenge associated with the implementation of AM in aerospace systems lies not in changing paradigms, but in the safe implementation of a new and rapidly changing technology. Compared to most structural material processes, the brevity in the timeline for AM implementation, from invention to commercialization to critical application, is unprecedented. Powder Bed Fusion (PBF) is the current leader among AM processes for producing metallic aerospace-quality hardware. In the PBF process, metallic powder is fused layer-by-layer into the shape of the part by a high-energy source such as a laser. After one layer of the part has fused, a fine layer of additional powder is spread across the part to create the next layer. As the part building process continues, the part rests within this bed of metallic powder, thus giving the PBF process its name. Multiple factors can influence the quality of the resulting PBF part such as powder particle shape, laser power, thermal conditions in the powder bed, residual stress development, and build chamber atmosphere. The requirements identified in this Standard establish a disciplined methodology intended to control these variables and manage risks associated with the process. Metallic PBF parts are a unique metallurgical product form. While there are similarities to other metallurgical processespowder metallurgy, casting, and welding, the PBF product is produced in a fashion that has no true precedent. Furthermore, the PBF process has not yet had the benefit of many years of incremental refinement by third-party practitioners, which typically provides the experiential and scientific foundation for the more traditional processes; undiscovered failure modes remain in the PBF process. For that reason, in some instances, this Standard offers a conservative approach to the requirements. The requirements of this Standard are intended to embrace AM technology and its benefits while respecting it as an evolving and meticulous process.