Production quality and batch verification
A type test proves what the product could do on the day it was tested. A production verification programme proves what it still does two years and three supplier changes later.
The prototype passed. That was two years ago.
Almost every acoustic performance claim in the market rests on a single test of a single specimen, often years old. Since then the supplier of the core material has changed, the density has been value-engineered, the adhesive is different and the line runs faster. None of those changes were made to hurt acoustic performance and each one is individually defensible — but nobody has measured what they add up to.
That is the gap batch verification closes. Not a new type test, but periodic confirmation that what leaves the line still behaves like the thing that was certified. It is cheap relative to a type test and it is very cheap relative to discovering the drift through a customer complaint on a completed building.
How to set it up so it is worth having
- Fix the specimen definition once. Same dimensions, same mounting, same conditioning, every time. A batch test that varies its own method measures nothing.
- Sample on a rule, not on suspicion. Quarterly, or per production run, or per raw material change — decided in advance. Testing only when someone is worried produces a biased record.
- Keep the original type test as the reference. The question is not what the batch scored, it is how far it has moved from what you certified.
- Decide the action limit before the first result. What deviation triggers an investigation, and who owns that decision. Agreeing it afterwards, with a bad number on the table, never goes well.