When key performance characteristics are critical to system performance, engineering will want to create a source control drawing in accordance with ASME Y14.24. The source control drawing will list specific supplier(s) that have been qualified to produce the product identified in the drawing. Engineering wants to use a source control drawing because the parts’ characteristics are critical to the design, and they do not want the parts procured from an uncharacterized source of supply. The source control drawing lists specific suppliers because those suppliers have met design requirements, and the engineering team has ensured the part is robust and has predictable performance. If the supplier’s parts being qualified demonstrate a drift in performance during qualification, the engineering team would not want to add these parts to the drawing because of potential fallout in production, unless the supplier can identify an effective corrective action.
Military and commercial product suppliers often overlook what is being asked by their customer when they are asked to qualify a part in accordance with ASME Y.14.24, Source Control Drawings. Often the data that come back are from a First Article Inspection (FAI) (AS9102:2004) that looks at mechanical and functional design characteristics listed on the drawing to verify that the production methods used produce an acceptable part to the engineering drawing. The FAI is nothing more than a subset of qualification data. This type of inspection falls short of what is required for design qualification when the design intent is being verified.
Impact on the design process. This misunderstanding of qualification often holds up schedule and produces budget overruns. The design authority then must reject the units at incoming and send the parts back to the supplier so that they may go back and qualify their parts to all the requirements, including environmental requirements. Military products need this assurance because often the products are mission-critical and high reliability is an essential criterion. When running qualification for a customer, best practice is to run an acceptable sample size to ensure a robust product.
The following sections discuss the difference between qualification and FAI:
Qualification. Qualification is the formal process by which a manufacturer’s product is examined for compliance with the procurement requirements of a source control drawing for the purpose of the manufacturer as a source of supply (ASME Y14.24, 2012).
A source control drawing provides an engineering description, qualification requirements and acceptance criteria for commercial items or vendor-developed items procurable from a specialized segment of industry that provides the performance, installation, interchangeability, or other characteristics required for critical applications. The drawing provides a list of approved sources of supply and the vendor’s item identification for the item(s) that have been qualified and approved for use in the critical application(s).The source control drawing establishes the source control item identification (ASME Y14.24, 2012).
Every part or assembly that requires qualification shall have a qualification test procedure that is approved by the purchasing entity. The qualification test procedure shall test all requirements. Test coverage is derived from design specifications and other requirements, such as safety standards or regulatory codes, where each requirement is verified by one of the following verification methods: test, demonstration, inspection, analysis, or similarity. If a test is being verified by similarity, the supplier must provide the data from the similar part.
Another important factor to note is that test coverage also feeds back to the design process, since the product may have to be designed to permit test access.
First article inspection. A first article inspection is a complete, independent and documented physical and functional inspection process to verify that prescribed production methods have produced an acceptable item as specified by engineering drawings, planning, purchase order, engineering specifications, and/or other applicable design documents (AS9102:2004).
First production run products shall be subjected to FAI, as defined in this procedure, on one of the first 10 items to be delivered using production tooling, processes, and documentation as defined in AS9102:2004 First Article Inspection.
First production run parts: the first group of one or more parts that are the result of a planned process designed to be used for future production of these same parts. Prototype parts, or parts built using methods different from those intended for the normal production process, shall not be considered as part of the first
production run (AS9102, 2004).
In conclusion, when comparing qualification and first article inspection requirements, it becomes clear that requirements and deliverables are different. Qualification is the method by which engineering can determine the interchangeability, critical characteristics, performance and reliability of components that meet the application, whereas first article inspection provides objective evidence of how the supplier is capable of manufacturing a part or assembly to meet the specification during normal manufacturing processing. A first article inspection is a subset of the qualification process.
The qualification procedure should include all requirements. If there are specifications that are not included in the qualification test procedure, the qualification test procedure should be modified to include the specifications identified. Hence, when a source control drawing is created or modified to add a supplier to the drawing, the supplier shall follow the definition of a qualification and not run a subset first article inspection to ensure production methods produce an acceptable part.