Appreciate the response, It is a cleanliness specification. Normally we get cleanliness specifications with max weight, but this one is max size, We have to prove we are capable Ppk 1.67.
I've seen people use defects per million to back-calculate ppk, but it has always seemed like fishy math to me ("What would my ppk be if my population was normally distributed and had this many DPM? Okay, I'll use that number.")
see this discussion for more info (from an internet search on "capability analysis no-go")
that obtains a size distribution of a particle fluid (gas) stream. It can be easily linked to a vacuum chamber or even an open air environment.
I'm not sure if this was what you were after, but it would surely define exactly what's in your medium in terms of particle size and distribution curves.
Have you investigated any consensus standards such as ASTM or ISO? Here is a keyword search of ASTM standards with "particle size" in the title or abstract:
I would get the size from the customer, then submit n# of sample sets, as normally produced, checked and shipped to an independent testing lab. tehy should be able to provide a statement or certified results on the size distribution of the contamination in the parts. Once you know the distribution and the # of lots, you should be able to calc your Ppk from there.
