Does the NIST certificate that came with my new ball-bar have any value?

[smryan]

The original cert that came with my new ball-bar claimed the center to center distance to be "3.973 inches". It was, in fact, measuring 2.987 inches. After a few un-responded to emails and finally an irate phone call they asked me to send it back. Over a MONTH later I had to email (and call because the email was ignored) to find out why they still had it. They'd decided I was right and "there must have been a typo" on the original NIST cert, so they would send a new one. The new one (same cert # tho) claims a "nominal 3.000 inches".

Based on 3 (or 4) digits worth of "typo" and beyond pathetic 'customer service' I have ZERO confidence in the company this was purchased from..... so is this cert as worthless as I feel like it is?

 

[silentrunning]

Re: Does my NIST cert have any value?

If you are using this piece of equipment on customer product, I would throw the cert away and send it off to a qualified lab and have it calibrated / certified. The cost will be well worth it in the long run. If it fails, send it back and shop elsewhere.

 

[smryan]

Re: Does my NIST cert have any value?

The ball-bar is used in our internal calibration check on our little CMM. The CMM itself will get professional certification on a schedule, so I'm not worried about that per-se. Just having doubts about the certs that we pay extra for when ordering new tools or equipment.

 

[Hershal]

First, every single cal lab and every manufacturer that sells calibration with their stuff, if they are in the US, claim traceability to NIST. That claim and $2 will get me coffee at AM/PM or 7-11.

What is the evidence? Where is the unbroken chain of comparisons back to NIST, complete with stated uncertainties at each step?

Thos are the questions you need answers to.

One other thing. If they give you the so-called "NIST Number" and cannot PROVE that the number relates to the specific calibration of their specific standard at a specific time, then the number is considered invalid and they do not have traceability. That is because - absent the ability to make that specific link - the NIST number is a work order number, nothing more, according to the NIST Policy on Traceability.

So, if you get proper information, then the cause of the difference is likely something else. But absent the ability to make the specific link, the cert is worth less than the paper it is printed on.

The bar itself may be adequate for your needs however. I would send IT to an accredited calibration lab and tell them to make sure the cert they give you have the accreditation logo and uncertainties.

Hope this helps.

 

[smryan]

It does, actually. Quite a lot. Tho I am somewhat embarrassed to admit that I hadn't even thought about digging into the NIST specifics.

 

[JAltmann]

I agree with Hershal. The tracability to NIST (or other national lab) is a great mis-nomer to those who don't understand how little that means.

Pretty anyone can claim tracabitlity to NIST by simply have a set of gage blocks that were calibrated by a lab that is accredited which will have instruments that are also tracable.

But many organizations are content to have the Xeroxed copy of a piece of paper so they can "check the box" for their audits.

Ultimately you get what you put into your systems, whether calibration, manufacturing, etc.

But i sounds as if your trying to do more than many, since it sounds like your peridically checking your CMM and questioning things when they don't match the stated values.

 

[BradM]

It does, actually. Quite a lot. Tho I am somewhat embarrassed to admit that I hadn't even thought about digging into the NIST specifics.

There's nothing to be embarrassed about here.

You paid money for something, and you expected, in Good Faith, that you were receiving a satisfactory product.

The refusal to reply to e-mails in this day and age is completely unacceptable to me . They deserve to be "flushed" by you based on that.

But more importantly, you need to have confidence in the calibrations being performed by you. After all... that's what it is for, to increase confidence in the measurement system.

I would dismiss any documentation from them, find a competent lab, and have them certify the product.

 

[Hershal]

It does, actually. Quite a lot. Tho I am somewhat embarrassed to admit that I hadn't even thought about digging into the NIST specifics.

Don't be embarrassed. I note that NIST does not go out of their way to call a news conference to put the information out!

 

[BradM]

This question came up again in a conversation. So in addition to Hershal's comments, this link to the N.I.S.T. site provides supplemental information:

http://www.nist.gov/traceability/suppl_matls_for_nist_policy_rev.cfm

I.B.4 Is a NIST Test Report Number necessary and/or sufficient evidence of traceability?

Test report numbers issued by NIST are intended to be used solely for administrative purposes. Although they are often used to uniquely identify documents which bear evidence of traceability, test report numbers themselves do not address the issues listed in I.B.1 above, and should not be used nor required as the sole proof of traceability
​