Key Points Prototype approval is not process validation: a first article inspection confirms the design works, but it doesn't prove your production process can repeat that result at volume Fixturing consistency is the most underestimated variable in the proto-to-production transition, and fixture drift quietly kills accuracy across a run Inspection strategy must scale with volume: sampling plans, equipment repeatability, and documentation requirements all change when you move from five parts to five hundred Process validation should be treated as a formal phase with defined acceptance criteria before production begins Supplier communication at transition is a known failure point. The engineer who quoted your prototype is rarely the one running your production floor When Prototype Approval Becomes a False Finish Line Getting a prototype approved feels like momentum. The design checks out, the dimensions are in tolerance, the fit is confirmed. Engineers move on. Program managers update their schedules. And then production starts, and the first batch has problems the prototype never showed.