Part classification is required to enable a consistent evaluation of part risk through defined metrics for consequence of failure, structural demand, and AM associated risks. Without carefully defined part classes, the ability to efficiently and accurately gauge the risk associated with AM parts within and across programs, projects, and suppliers is lost, resulting in risk mitigations that are either not commensurate or not consistent. The classification system in this Practice establishes a consistent methodology to define and communicate the risk associated with AM parts. These classifications are used in material and process specifications to determine the appropriate levels of process control, thermal post processing, qualification, and inspection to ensure parts meet the required application. The part classification system uses a two-tier system to designate PBF parts based on relative risk. The alphabetical class is determined by consequence of failure The numerical subclasses of Classes A and B are determined by a combination of structural demand on the part and the risk associated with the AM implementation for the part. Class C have low consequence of failure and negligible structural demand. The classification system stems from the three primary questions typically asked when first evaluating part risk: 1.What happens if the part fails? 2.How severe is the stress environment? 3.How challenging is the part design and can it be reliably inspected? This classification methodology is only applicable to metallic parts, however, polymeric materials could also be similarly classified with minor changes to the decision criteria.
The title and scope are in draft form and are under development within this ASTM Committee.