The original intent of certificates of compliance was to make sure that process steps were not overlooked if they could not be verified later. An example of this might be a product that has to be dipped in a specified solution at a specified temperature for a specified period of time before painting or plating. Usually, there is no way to verify that these steps were taken once the product has been coated. Testing after-the-fact can reveal that the correct thickness of paint or plating has been applied but not that all specified process steps were followed.
Other than monitoring the entire process at the vendor, the only comfort the customer can get is through the use of a certificate of compliance.
On the other hand, calibration reports provide data that can be obtained after the item has been made to determine if it meets specifications from a dimensional point of view.
It’s easy to understand why one document is not the same as the other. Yet, many gage and instrument suppliers consider one as good as the other and issue certificates of compliance for gages in lieu of proper calibration reports. Many quality managers and auditors alike will accept the substitution.
One reason for this is cost. It costs money to have a gage calibrated in a proper manner. When certificates of compliance are involved, the item is rarely, if ever, calibrated to confirm that it is within tolerance; this reduces costs significantly. Certificates of compliance are usually offered “free” because the only work involved is having a clerk write a few generic details on a form.
Regardless of the fancy wording found on some, certificates of compliance are no substitute for a calibration report. Some of that wording may make you think otherwise. For example, it may include statements such as “...has been made in compliance with standard B1.xxx.” In other words, the standard cited was the target but, without calibration, you have no way of knowing whether the gage hit the target-let alone the bull’s-eye.
The problems get worse when a measuring instrument is involved. Without calibrated values on the performance of the instrument, you have to take a worst-case scenario when you produce an uncertainty budget that involves the use of that instrument. An actual calibration report may show that the instrument errors are well within the maker’s accuracy claim and may be insignificant if you are only using a small portion of the measurement range.
The true cynic will suggest that if you paid nothing for a certificate of compliance, that’s just about what it’s worth. When an item such as a gage can be measured to determine compliance with a specification, certificates of compliance are useless bits of paper that cannot prove or confirm anything.
As I mentioned earlier, cost is often the reason why people accept certificates of compliance rather than a proper calibration report. Believe it or not, those who have highly touted quality programs are sometimes the biggest users. You can bet their paperwork is very well organized even if some of it means nothing.
Some companies are essentially collectors of paper-one piece per gage, please-so it occurred to me that there was a business opportunity at hand. I could print a bunch of these “certificates” and leave room for the customer to fill in the blanks. Obviously, these “certs” would list the name of a fake company as the supplier but since few question the validity of such “certs,” are they likely to bother trying to find out if it’s a real company?
I’m sure someone is already into such a scam. Come to think of it, I haven’t heard of the Feds busting counterfeiting rings in a long time. Maybe that’s what the bad guys are into these days. There’s an insatiable demand and the government won’t bother them as much. After all, like governments everywhere, they’re too busy printing counterfeit money legally.