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Automatic Passivation Equipment - and Control Of

We are looking at automating our passivation process. The equipment would wash, rinse, passivate, and rinse the parts in self contained equipment. My main questions are related to maintaining auditable quality standard (particularly NADCAP). How are others making sure the parts are chemically clean prior to passivation (with the equipment we would not be able to do the water break test). Also, what are the standards for determining when the Nitric Acid or should not be used? (I am told we could be able to use the solution for up to 1 year before needing to dump it.)

B. Arnold:

You should validate your automated process by testing and establishing your defect(out of specification) rate after the cleaning process and after the passivation process. Statistical sampling of your validated online process and testing for cleanliness by an approved method (water break test or surface chemistry analysis) or testing for passivation by approved method (salt spray test or ESCA/Auger chromium to iron ratio testing) would produce auditable quality records.

Nitric acid concentration can be tested as well as the iron concentration in solution. Depending on the specifications to which you are processing, a rule of thumb is iron concentration to remain below 2% by weight.

Thanks, Daryl.

Refer to AMS2700 for guidance on the process. Many of our customers are meeting NADCAP requirements easily by validating the process and verifying the results by ongoing tests. Let us know if you need help setting this up.

I understand that 2% Iron is max. in the bath, but can anyone help me out with the procedure.
We are starting a passivation line and I am having trouble finding this one.
I'd appreciate anyone's help.

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