Your metal finisher may be Nadcap (National Aerospace and Defense Contractors Accreditation) certified for chromating, and may have good Quality Assurance policies and procedures in place, but there’s one thing they may fall short on: Communication. Each job is different, and your metal finisher has to know what you need for your parts and when you need them.
Does the metal finisher work with you during the quote process to make sure that they fully understand your needs? When the parts are received, what communications do you desire? If one of your parts has errant fingerprints, are you sure they’ll communicate with you on what they can do to correct the problem? Do they regularly update you on the status of your job while the parts are being finished? Do you get shipping estimates and shipping updates?
In addition to picking a metal finisher based on qualifications, you also need to pick one based on their ability to keep the lines of communication open from the very beginning to successful end.