Where it started
Six weeks before design verification of a new autoinjector, characterization testing on several thousand units showed the glass syringe fracturing in about one drop in 800. The filing date for the combination product depended on the device passing verification. The parts for verification were already produced.
The strategic question
Redesign the device and move the filing. Or take a calculated risk: go into verification with the parts on the shelf, knowing a pass was likely but not certain, and fix the design afterwards.
What we found
Root cause first. The fracture traced to a housing component adjusted late in the program to ease assembly. The change left less material where the syringe rests on impact. High-speed camera and simulation confirmed it.
The verification plan added its own risk. The client’s own quality procedure fixed the sample at ten units with zero failures permitted, so a single fracture would fail the test. ISO 11608-1 also allows attribute plans with a defined number of accepted failures. With 32 units and two failures permitted, one fracture no longer decides the outcome, and a pass demonstrates higher reliability at the same 95 % confidence. The standard allowed the larger plan, but the client’s own procedure did not. The procedure had to change first.