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Dimensional changes after bluing process

I work for a small aviation based business and we've run into something that has us all stumped. We recently had some parts sent for bluing through a process called high velocity impingement. When the parts were returned they no longer fit in their respective assemblies.
The parts were machined from 17-4 PH H900 stainless steel. So we're not talking soft material here. My question is how can the bluing process change the dimension of a part and has anyone else ever had this problem? Any feedback whatsoever would be greatly appreciated.

C. Warren Musselman II
Airflow Performance, Inc. - South Carolina, United States
2005

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Traditional bluing (black oxiding) does not alter the dimensions. But "high velocity impringement", whatever that is, is not traditional bluing. With nothing to go on but the name, it sounds like the parts were flame sprayed with some coating material, which would certainly change the dimensions.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005

I've asked around for some time with no definite answer to this. What is high velocity impingement as it applies to a bluing process?

C. Warren Musselman II
Airflow Performance, Inc. - Spartanburg, South Carolina
2005

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2005

Warren, if you would put your question in context, it's possible that someone could help. But "high velocity impingement", which only means that someone is claiming something hit something at high speed, doesn't seem to be getting you anywhere. Unfortunately, anything from a home run to a car crash is high velocity impingement.

Is the process called out on a drawing? If so, who wrote the spec? Is the vendor claiming to offer it? If so, does it mean anything to anyone at the vendor except your local silver-tongued salesperson? Who is it that says the process involved "high velocity impingement"? Why did you send the parts out for "high velocity impingement" is what you wanted was bluing? You haven't said if the parts are bigger or smaller, although I'm inferring that they're bigger.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey