In a centralized database it is allways possible to cheat. I think something like qualitiy data from a factory. Once you stored the data, there will be no way to change it later.

Why would a vendor cheat in a database that contains only a list of legitimate parts from the vendor? It is in their interest to sell those parts and not have any knock-offs sold.

The same goes for quality data, mostly because even if the vendor provides it, basically any industry partner will absolutely insist on doing sample tests on the quality anyway. That also doesn't remove the factor where the quality results are cheated before being put on the blockchain.

A blockchain is not very useful when

A) all participants are trusted or

B) there is no incentive to cheat or

C) if there is incentive to cheat there are already countermeasures available that are more useful (ie, doing samples and having a contract that specifies damage payments in case quality does not match)

Since you have to, at some point, trust the manufacturer that they built what they said they built, there is no point in a "trustless" system.

Second, you have yet to actually provide any motivation for end clients to spend money or hardware on a manufacturer's blockchain. Chances are the manufacturer would have to maintain all the miners, which is silly.

Third, the manufacturer in this case would have all of the signing keys, since they're the only ones that can make parts. This also damages the selling point of the blockchain.

So no, this does not work.

As noted by other commenters, in most of the immutable data use cases that I have seen, these ignore the much greater business and operational risk placed in your counter-party. For instance, I place far more trust in an airline to get me from A to B alive and safe than I do for them to honor the fact that they issued me a ticket. We've already established a much higher level of trust based on profit (i.e. dangerous airlines lose customers) and thus a blockchain doesn't really add anything.

I think the point the earlier posters are trying to make is that if a manufacturer is at a point where they need an immutable, decentralised quality record their problems are bigger than the record keeping. As someone buying parts you generally want to trust the manufacturer you're buying from, as someone making them, if you're at the point of making crap and faking records your days are probably numbered anyway.

If you somehow managed to persuade an industry to get on board, for the most part, those with nothing to hide are the ones a decentralised quality database is the least useful for - anyone trying to hide anything (manufacturer / buyer) is going to avoid taking part or cut corners anyway.