NOTE: This was posted by Jason on the 'old' forum:

Hello All,

My company has a set of standards (ranging from 1" - 24") that we sent out to be calibrated by a certified QS company. This set is considered the "Master A" set which is the calibrated set. We also have another set consisting of the same standards, but we consider this set to be the "Working B" set and this set is not calibrated. We have 4 pairs of tubular "C" outside diameter micrometers ranging from 12" - 24". My question is: What is the appropriate method or procedure to verify our micrometers are accurate using both sets?

We want to set up our system so that our operators will "work" with the "B" set & then every 6 months to a year, check the mics agains the "calibrated A" set. Could this work for us & how would you record all of our actions.

Thanks...

[Note: This message was edited by Marc Smith]

Jason,

Dick responded to your original posting (which I reposted here) on the 'old' forum. I know you saw Dick's response, but for others it was/is as follows:

-------snippo------

Posted by Dick Lyons on Sunday, 28 June 1998, at 8:38 a.m., in response to Calibration & Verification, posted by Jason on Friday, 26 June 1998, at 6:04 p.m.

Calibrate your "Working B" set by comparing them to you calibrated "Master A" set. Now you can be confident that the operators have accurate standards to work with. This also allows the operators to double check their mics and other equipment against a known measurement anytime between calibration intervals.

Note from Marc: These 'comparisons' have to be documented in your Calibration System...

There are several software programs available that will provide you with the ability to record your calibration data as well as guide you in developing a good calibration system. Try downloading a GAGEtrac demo from from CyberMetrics Corp. at http://www.visit.com

Note from Marc: This url may be (pretty sure it is) incorrect. Hey Dick - What Say You????

to get an idea of what is out there. There are other packages but I just happened to have that one in front of me. Good Luck.

---------snippo--------

Now - Your last post on the 'old' forum:

I guess this message is for Dick Lyons who replied to a recent inquiry that I had... Dick, thanks for the reply. If there is anyone else out there with some knowledge of my needs, please feel free to reply to.

Dick, you suggested that I should look at CyberMetrics at www.visit.com, so I could download Gagetrac. I tried opening up this site, but I cannot get to it. Is this the correct address? It would be great if I could download something that is inexpensive to keep track of my company's calibration & verification procedures.

For those reading this message for the first time, I'll restate my inquiry. My company has 2 sets of standards that range from 1" - 24". One set is considered the "Master A" set which is the calibrated set. The other set is the "Working B" set which is not calibrated. We want our operators to use the "work" mainly with the "working B" set & periodically (6 months to a year) veryify their mics against the "Master A" set. I am looking for some formal inexpensive way to record our data and to meet QS requirements. Our data system doesn't necessarily have to be some high price computer software system either....but, of course, I'm sure that is more preferred.

If someone had a form that they use to keep track & control their calibration &/or verification procedures for their measuring instruments, it would be great if you could attach an example to my e-mail address:

my_con@email.msn.com

Marc Note: E-mail me a copy and I'll post it for everyone!

---------snippo-------

Now - This is in response to your Sunday posting on the 'old' forum.

You can make a form in a FilemakerPro, Access (if you support Bill G.) or another other database (FoxPro comes to mind) for ease, or just make a form in excel or other software. I've seen small companies actually comply with a paper system (but I don't recommend paper systems). The form needs the basics (like equipment type, serial number, etc.), but the main items are: reference point(s) being checked, 'before' reading(s) and 'after' readings.

You would be best off purchasing calibration software which addresses all the issues. The tradeoff between time maintaining a 'borderline' compliance system and just purchasing the software is - well, buy the software... You'll save in the short run, not to mention the long run... You won't regret it!

More and more registrars in QS are requiring proof of competancy in MSA so be careful. Someone in your company really (no kidding) has to understand MSA as a whole (the David Letterman Sky-Cam view) and be able and ready to explain how you 'comply'.
[Note: This message was edited by Marc Smith]

Try a search for CyberMetrics. I did this morning and was successful. There were several CyberMetrics listed but I selected CyberMetrics Corp. and went right to their page. If that doesn't work for you, give them a call at 1-800-777-7020 and have them send a demo disc.

Hope one of the above gets you the info your looking for.

Does this work? Hey Marc & Company....this new forum is kind cool & quite different from you previous forum. Is the other forum still accessible & if so, how much longer? When I post a message here, will I get my replies directed to my personal e-mail address, like the other forum did?

Well, for now, that's all I'll ask. I'll come back with my QS questions later.

The old forum remains up. I plan to leave it there as an info resource but *not* for any new posts.

I'm not sure about all of the software features yet. I know if you initiate a thread you have an e-mail option. I haven't seen where people responding have that same option. There are pros and cons to this software like all other software.

Jason, Microsoft Access is an excellent program to set up your data base. When you look at the sample software consider how many gages you need to conduct your verification on. Many of these software packages may have a lot more whistles and buzzers than you need. However, if you are not familiar with gage R&R protocol, you may want to have that included in the package. Many companies have talented personnel that write and design data bases, you may be able to complete your program by utilizing internal programers.

Use caution if you use microsoft's Access - it is not Y2K compliant. I forget whether they hacked a temporary pivot date fix or library lookup. But - testing has shown it is flakey (as is most microsoft software).

A 'stolen' Thread:

From: nicolet.com (Doug Pfrang)
Subject: FYI: Calibration/Pfrang

1. As I said before, you do not necessarily need to CALIBRATE a tool unless you first determine that there are no other cheaper alternatives for VALIDATING that tool in your process. Therefore, to all of the ISO consultants out there who have tried to advise people on whether or not to calibrate a tool: you should never suggest that any tool be calibrated until you first determine whether or not that particular company has any other cheaper alternatives for validating that tool (e.g., brute force trial and error). Virtually none of the ISO consultants who have posted to this list appear to do this; instead, they appear to use some other surrogate (and incorrect) criteria for determining whether or not to calibrate a tool. Often, the suggestion is to calibrate the tool simply because the person making the suggestion can't think of any other way to validate the tool (i.e., because they haven't explored this option with the client), and they know that calibration will be easy to sell to the ISO auditor. While this is certainly the easiest advice to give from their point of view (since it is virtually guaranteed to work, and thus make them look good), it is not necessarily the most cost-effective solution for the client.

2. Keep in mind that validating a tool by calibration does not mean the tool is any more reliable than if it is validated by brute force. In either case, the tool can drift out of accuracy between the time you validate it and the time you use it. Therefore, the time interval that you choose between revalidations is NOT a function of your METHOD of validation, and it is NOT a function of the calibration cycle recommended by the manufacturer of the tool; it is SOLELY a function of how stable that particular tool is in YOUR particular process. In other words, you do not automatically have to revalidate a tool annually just because that is what the manufacturer recommends. You may freely adjust the revalidation cycle longer or shorter based on YOUR OWN experience with that tool. If the manufacturer recommends that you recalibrate a tool annually, but you find it perfectly adequate -- in YOUR process -- to revalidate that tool every decade, then you are perfectly justified in revalidating that tool every decade. Similarly, if the manufacturer recommends that you recalibrate a tool annually, but you find it unacceptable -- in YOUR process -- to wait more than six months, then you must shorten the revalidation cycle to six months. YOUR experience with the tool, not the manufacturer's recommendations, governs the length of the revalidation cycle. Thus, if you have a tool (for example, a tape measure) and your experience shows that -- in YOUR process -- you can go ten years before revalidating that tool, then that duration is perfectly acceptable as long as you have some reasonable basis for setting the revalidation cycle at that length. How do you show you have a reasonable basis? Just keep a record declaring that you have used this type of tool for ten years and -- in YOUR experience -- these tools haven't gone out of spec in that time frame, so YOU are going to set the cycle at ten years for YOUR process.

3. Many people have posted statements to the effect that "the reason we don't need to calibrate this tool is because we don't need to make accurate measurements with it." This analysis is also wrong. The ACCURACY you need for your measurement is IRRELEVANT to the question of whether or not you should CALIBRATE a tool. The ACCURACY you need for your measurement is only relevent to your SELECTION of which tool to use: the tool you select must be capable of the accuracy you require. Once you SELECT a tool that is capable of the accuracy you require, whether or not you choose to CALIBRATE that tool does NOT depend on the accuracy you require; the decision to calibrate it depends SOLELY upon your assessment of whether or not calibration is the best way to VALIDATE that tool for your particular process. Therefore, to say that "I don't need to CALIBRATE this tool because I don't need to make accurate measurements with it" is wrong. The fact that you don't need to make accurate measurements guides your SELECTION of which tool to use, but your decision not to CALIBRATE that tool is based on the fact that you can VALIDATE that tool easily by brute force trial and error. You try the tool in your process and it works for you; therefore, you have VALIDATED it without having to CALIBRATE it, and THAT is the reason you do not have to calibrate it. But then they make the mistake that most people do -- the mistake which leads to most ISO nonconformities related to calibration -- they neglect to document their validation, which is discussed below.

4. The root cause of almost every ISO nonconformity related to calibration is NOT that the company has failed to CALIBRATE a particular tool; the root cause of the nonconformity is that the company has failed to provide an appropriate QUALITY RECORD showing that a tool has been VALIDATED for the given process. ISO auditors do not looking for calibration records per se; they look for QUALITY RECORDS showing that tools have been VALIDATED for the processes in which they are used. The reason that companies often (wrongly) interpret such nonconformances as requiring the tool to be calibrated is that calibration provides a handy QUALITY RECORD for the company's files, which resolves the nonconformity because it provides adequate evidence of VALIDATION of the tool. However, in virtually every instance, the company could also resolve the nonconformity without calibrating the tool, if it would simply VALIDATE the tool using some other appropriate method and produce a QUALITY RECORD showing that the tool has been VALIDATED and the method by which validation was done.

-- Doug Pfrang

And an interesting follow-up:

From: nicolet.com (Doug Pfrang)
Subject: Re: Calibration/Pfrang/Volker/Pfrang

> Your example is not very illuminating for real-world problems. You
use
>a wrench and it turns the nut without damaging it-- fine. Your wrench
>is not an instrument, it's a tool. People don't calibrate "5 mm
>wrenches". You would probably want to calibrate a torque wrench,
>however. How do you "brute force validate" that??? Say you're
>installing motor cylinder heads. You do 100 motors and everything seems
>fine. "Brute force validated"? What happens if in a year some of them
>start warpping because they were unequally stressed? Would anyone ever
>even know that the problem goes back to your torque wrenches? Does it
>make any difference if no one figures out the root cause?
>
> Is it possible to "brute force validate" anything, if your process
>produces occasional non-conforming products?
>
> In the real world we often don't know why a product fails-- there
are
>too many variables in production to pinpoint the exact cause of
>failure. That's why quality systems such as ISO 9000 lay such great
>importance on constancy of process and calibrated measurements.

OK, maybe my example was a bit too simple, so let's back up and see if we can clear things up. First of all, let me repeat that the main point of my posting was that calibration is a SUBSET of validation. This is a really key point, because many people have been posting questions about calibrating things that obviously could be validated more easily by brute force; namely, things like tape measures and injection molding machines. My point is that IF you can validate a device more easily by brute force trial and error, then you do not HAVE to calibrate a device just because it has numbers on it or just because it makes a measurement. You CHOOSE whether or not to calibrate a device based on whichever method of validation makes the most sense in your particular process.

Second, when it comes to CHOOSING whether or not to calibrate a particular device for a given task, it makes no difference whether we label that device a "tool" or an "instrument." ANY device (even an "instrument") CAN be validated by brute force, because the only thing you care about is whether that device does what you want it to do in your process. A 5 mm wrench, a torque wrench, a voltmeter, a soldering iron, whatever. They are ALL "tools." If you want to label some of them "instruments," that's fine, but I think that tends to confuse people into believing that the decision process is different for "instruments" than it is for "tools." In fact, it's not, and that's another point I'm trying to make. Whether we call something a "tool" or an "instrument" doesn't change the analysis at all.

Let's take the torque wrench example. In your example, the engines fall apart a year later because of UNEQUALLY stressed parts. This problem is obviously NOT a result of the tool being UNCALIBRATED; it is a result of the tool being DEFECTIVE: the bolts are UNEQUALLY stressed because the tool's readings are not REPEATABLE. You cannot resolve this problem by CALIBRATING the tool; you must resolve this problem by REPLACING the tool, because, in your example, the tool is broken. It can't make repeatable readings.

Now, let's use the same tool, but let's use a torque wrench that isn't broken. You're building an engine, you want to torque the head bolts to a torque that will hold the engine together, and you have a torque wrench that is not calibrated. The question is: do you need to calibrate that torque wrench or not? Well, as I said before, the answer to this question depends totally on YOUR PROCESS, NOT ON THE TOOL. Let's say YOUR PROCESS is to build engines where SOMEONE ELSE has already determined what the torque should be. Ford Motor Company TELLS YOU that the torque on those head bolts must be 85 ft-lbs. OK, fine, FORD has VALIDATED that torque value by some method (possibly their own trial and error), so YOU don't need to VALIDATE whether 85 ft-lbs is right or wrong. All YOU need to do is ensure that you torque the part to 85 ft-lbs, and you know ahead of time that this value will work. How will you do that? Well, probably by calibrating your torque wrench so you can torque the head bolts to 85 ft-lbs.

But now, let's change the process. Let's say YOUR PROCESS is to build engines where someone else has NOT already determined what the torque should be. You're building a custom race engine, using your own head casting, and you don't know what the torque should be because no one else has VALIDATED the value for you. So, does it matter whether your torque wrench is calibrated or not? No, it doesn't, because you don't know if the torque should be 25 ft-lbs, or 90 ft-lbs, or 115 ft-lbs. Sure, you might use the numbers on your torque wrench as a REFERENCE, because in your experience you believe that the torque should be somewhere between 50 and 100 ft-lbs, but you don't know what the torque really needs to be. So, calibrating your torque wrench does NOT answer the question of what the torque needs to be. HOW do you determine what the torque needs to be? By brute force trial and error. You torque the part to some value and give it a try. In this example, it really doesn't matter if the torque wrench is calibrated or not, because you're not trying to hit a specific torque value that someone else as validated for you; you're just trying to hit a value that holds your custom engine together. In fact, you could just as easily use a torque wrench that has no numbers on it at all -- just a blank dial -- and you could simply put a mark on the dial that corresponds to how far you torqued the head bolts each time. Then, if you discover that you torqued the bolts too tight or too loose, then you just move the mark up or down a little until you get it right. Once you get the torque right, you just use your little mark on the dial as your personal indicator for your custom engines; and this method works just fine in YOUR PROCESS, because you're not trying to match some factory torque spec that someone else validated for you. Now, do you need to run out and calibrate that torque wrench? No, you don't, because you have VALIDATED that torque wrench in YOUR PROCESS by brute force trial and error.

And the same analysis applies to ANY device in ANY process, and it makes no difference whether the device is a "tool" or an "instrument."

> Once you start covering yourself a lot of documentation, then you're
>really just "calibrating" with your own home-made procedure; the
>distinction between calibration and brute force validation seems lost to
>me, then.

That gets back to the main point I was trying to make: that calibration and brute force validation are just two sides of the same coin. The mistake that I see people making all the time is that they see the record-keeping requirement in the ISO-9000 standard and they think they need to run out and hire a third-party to calibrate every piece of equipment in their facility. As a result, they talk about calibrating things like tape measures and injection molding machines, and some of them spend a ton of money calibrating things that don't need to be calibrated. That's wrong. What I'm trying to do is get readers to see that:
(1) they have an ALTERNATIVE to calibration -- namely, brute force validation -- which they may use as an OPTION in appropriate situations; and
(2) the decision-making process that people should go through to DECIDE which validation method is best depends ENTIRELY on each facility's SPECIFIC PROCESS and NOT on the TYPE OF DEVICE being used.

True, no matter which validation method you chose, the ISO-9000 standard says you need to have records showing that your equipment is validated, but HOW you VALIDATE your equipment is up to you. In some situations, it makes more practical sense to VALIDATE a device by CALIBRATION, but, in other situations, it makes more practical sense to VALIATE a device by BRUTE FORCE. Whether you call your equipment "tools" or "instruments" DOES NOT MATTER. What matters is that you validate your equipment, and that you have records to prove it.

To sum up: the ISO-9000 standard mandates that you keep validation records for every device in your facility that impacts product quality, but it does NOT mandate HOW you validate every device in your facility that impacts product quality.

-- Doug Pfrang

My job is to design a data acquisition system for an enviromental chamber which will be used for package testing. I have an option to buy a complete system, which would enable me to easily calibrate thermocouples on site, from one company, however their price is unreasonably high.
Thus, I am trying to use a combination of equipments from different companies (data loggers, calibrators and thermocouples). I would really appreciate if somebody could answer the following question:

After one notices a drift in the calibration of the thermocouple (using a dry well or a temperature bath), is there an automatic way to compensate for it? Or would I have to send the faulty thermocouple to an outside lab?

I'm old school, but as I remember when a thermocopuple started to drift we re-welded the end of the thermocouple and evaluated the monitor box. The thermocouple only provides a voltage or resistence at a temperature. This is to say you calibrate the box which measures the wire resistence/voltage - not the thermocouple. I would think you would have to repair the box if there is a drift. I do not know of a simple 'corrective' device or method.

Has anyone attempted to define calibration differently in terms of an ISO 9002 document.

Example: We make an adjustment to a pressure system that is electronically controlled by a board and an adjustible pot. We call this calibration because we are verifying that the specified range of pressure is available.
We would like to define calibration differently for our purposes. In other words, calibration as used by us in our documents means to make adjustments and not to reference to any standard. What are your thoughts? Would a registar buy this argument?

Thanks,

Ed

Ed,

We went through a situation with an auditor with the following outcome.

1: If a gage is truely calibrated it is sent to a cerified lab (or a certified internal lab), calibrated to a traceable standard. I.E. a gage block set, CMM, Surface Plate, Rockwell.

2: If a gage is mastered, set, or tested to one of those "Calibrated Standards" by the use of an internal schedule, we are only verifying the current state of calibration.

This scenario came about by our use of multiple dial indicators that were not truely "Calibrated" but only verified to a calibrated standard on a monthly basis.

I believe that the adjustment of your "gage" is not a true calibration but a verification that your gage is performing within a pre-determined, acceptable range.

As usual there are many opinions on this subject. If the gage calibration and verification standards are precisely documented in a lab manual (or procedure) and the system is followed there would be a good arguement to your registrar for your methods.

One thing to consider when setting frequencies and standards is the Bias, Linearity, and most importantly the ongoing Stability of the gage/tool in question.

If you email me I can send you some excel spreadsheets that might help you determine the ongoing performance of measurement systems.

I like the acronym I have recently seen.
IMHO (In My Humble Opinion)

ASD

Ed,
Is what you are doing, calibration?
It beats me!
According to my pocket dictionary, calibration is marking the scale of a measuring instrument, so that would seem to say that you are not calibrating, but the word originally meant 'to determine the calibre of a gun' and I'd bet there would be a few older definitions available which might well fit.
I can imagine that it will cause more confusion to change it than to go on as you are, and, if you think this is so I'd say, use calibration and change to 'verify range' if some auditor gives you a problem. Either way, it has no impact on your calibration program as long as you are not confused between the ISO meaning and your specific use. If is causes a problem, then change. If it doesn't, then don't worry.
rgds, John C

Ed,

Calibration is specifically defined in several international standards as, essentially, verifying the performance of a measuring instrument to a specified standard. In other words, calibration is always a documented method of verifying the performance of a measuring instrument, usually under controlled conditions, and always by comparing it in some way to a specified standard.

The result of a calibration is data that allows you to make a quality decision about the performance of the instrument. One of many decisions you might make is to adjust the instrument -- and after the adjustment you will need to calibrate it again. However, all calibration procedures start with the asumption that the instument being calibrated is in proper working order. A purpose of calibration is to determine the degree of truth of that assumption.

There are several common but incorrect usages of the word "calibration".

Adjustment of a measuring instrument. (Calibration provides the data that tells you something is not correct. What you do in resonse to the data is a quality decision. Adjustment is one possible decision, and is a repair action. Adjustment when it is not needed falls under Deming's definition of "tampering".)
Alignment of new instruments at a factory. (That is part of the factory production process for the item, not a performance verification test.)
Standardizing a measuring instrument before using it each day. (That is part of operator setup. Calibrated tools or standard methods are probably used, but the standardization itself is not calibration.)


Repeated use of "calibration" in these incorrect ways only perpetuates the confusion among all of us. In a quality system in particular, it is my opinion that words defined in national and international standards should be used only in the ways they are defined. If nothing else, it will reduce the amount of time you have to spend educating your assessors each time they visit!



------------------
Graeme C. Payne
ASQ Certified Quality Engineer

Ed

I have to agree with the rest of the comments. What you are doing appears to be verification of the equipment, not calibration.

During a recent pre-audit I was involved in, the auditor mentioned that a check of the range or operating point prior to use is verification not calibration. Within the ISO 900x family calibration has a specific definition that requires a comparison, under specific conditions, against a known standard with a unbroken path back to a internationally or nationaly recognized standard.

Ok, we are in the same boat. We make, rework and calibrate/certify Spline Gages and Gears. When we use a master say on our M&M gear checker. Are we calibrating the machine or verifing. Oh, I have a better one. This uncertainty thing is a joke. I have sent out a indicator for calibration. .0001 grad. It comes back with .00008 uncertainty. Give me a break.

Edward, When you make adjustments to ensure the specified pressure range is available, presumably you need to measure that pressure somehow? If the measuring gauge (gage in US?)is itself calibrated (i.e. verified to conform to specified limits of uncertainty, and traceable to a standard) then you are indeed calibrating. If your measuring gauge is not calibrated, then you cannot claim your product meets its specified pressure range.

I had second thoughts about this so I've edited it out. In fact, I tried to do this yesterday, shortly after I sent it, but had problems with my system.
John C


[This message has been edited by John C (edited 24 December 2000).]

Graeme C. Payne,
You quoted a definition of calibration and prove it by saying that certain international standards use the same definition. I did some web surfing and looked in three dictionaries and have to report that they come down heavily on the side of the 'check and adjust' definition. One dictionary gave both; the 'mark a scale' and a version similar to your definition.
Regards International Standards; My ISO 9001:2000 agrees with the 'adjust to standard'; It says, in 7.6; 'calibrated or verified', note, not 'calibrated and verified'.
So who am I to believe?
It seems to me that, as is common, both definitions can be acceptable though yours may be strictly more correct.
But, when it comes to 'confusion'; Who is confused? Until we read your letter, no-one was confused. I send my out-of-tolerance scales away to be 'calibrated', to my 'calibration' lab service and they come back checked and adjusted. I send my cheque and thank the guys for calibrating it. They say; 'That's no problem, that's what we do. We like doing it'.
I'm happy, the calibration boys are happy and everyone else does the same and they're all happy.
Now, after your posting, the thing will come back with a note saying it's out of tolerance and an invoice for $30 for 'calibration'. Well you can bet they won't get the $30. So they're unhappy, I'm unhappy and everyone else is unhappy.
Except you. I suppose, then, you'll be happy.
rgds, John C

As John C mentioned, different dictionaries have different definitions of "calibration". So do different international standards, which is what a quality systems auditor is more likely to be referring to. As I said earlier, "calibration" is a word where there may be significant differences between the technical definition and the common usages.

Going back to Edward's original question - is it permissible for a company to redefine "calibration" in a way that leaves out any reference to a standard. Again, my opinion is a strong "NO". The one thing that is constant in technical definitions of calibration in the international standards (norms) is that the essential part of calibration is comparing a measuring instrument of unknown accuracy to a measurement standard (etalon) of known value and uncertainty.

Reference:
International vocabulary of basic and general terms in metrology (ISO, 1993):
"A set of operations that establish under specified conditions the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding value realized by a standard.
Notes: 1. The result of a calibration permits either the assignment of values of measurands to the indications or the determination of corrections with respect to indication.
2. A calibration may determine other metrological properties, such as the effect of influence quantities.
3. The result of a calibration may be recorded in a document, sometimes called a calibration certificate or a calibration report."

The definition above is included by reference in the new ISO/DIS 9000 and ISO/IEC 17025:1999, and is included verbatim -- but without the notes -- in ISO 10012-1:1992 and ISO 10012-2:1997. An essentially identical definition in the United States is in ANSI/NCSL Z540-1:1994; the only substantial difference is the addition of one note relating to calibration factors and curves. Essentially identical definitions are also in other sources, notably the NCSL Recommended Practice 1 on calibration intervals.

In addition to the essential core of calibration (above) most technical definitions in the United States do include the concept of adjusting an instrument, usually as one of several possible actions. Some international standards also include this. Almost all calibration laboratories will, as part of the added value of the calibration process, adjust an out-of-tolerance instrument. (Personally, I would not use one that does not - and all of the labs I have worked with do adjust instruments.) However desirable, though, adjustment is not an essential part of "calibration" as defined by ISO.

The most common additional definition in the United States is:
"the comparison of measuring and test equipment or measurement standard of unknown accuracy to a measurement standard of known accuracy in order to detect, correlate, report, or eliminate by adjustment any variation in the accuracy of the instrument being calibrated."

This or essentially similar definitions appear in a number of US references: NCSL Recommended Practices 2 and 3; MIL-STD-1309D; MIL-STD-45662A (canceled in 1994); NIST Special publication 260-100; ANSI/ASQC M1-1987. A similar definition appears in ISO 10012-1:1992 and ISO 10012-2:1997 under the label "metrological confirmation". Note, though, that the core concept is still comparison of a measuring instrument to a standard, just as in the ISO definition. "Adjustment to remove variation" is simply one of several actions that may be taken. Therefore, my earlier message was incorrect to this extent, because in that I was referring only to the ISO definition which does not include any of the actions that result from the comparison.

In the actual practice of calibration laboratories I have worked in and with for may years, the generalized calibration work process flow looks something like this --
Start
Compare the instrument under test to a measurement standard. ("calibrate" it.)
If the performance is within specifications,
Report the results and return the instrument to the customer.
Otherwise,
Report the out-of-tolerance condition to the customer.
If the instrument can be adjusted to meet specification,
Adjust the instrument in conformance to lab policy.
Go back to start.
Otherwise
Consult the customer and lab policy for appropriate action.
If the instrument is repaired, go back to start.
End

To return to Edward's original question yet again: every technical definition of "calibration" that an auditor is likely to refer to states the core concept of comparing an instrument to a measurement standard. If you are not doing that, then you are not calibrating. And if you are adjusting your instruments without reference to any measurement standard, you are making the indications on the dials (or whatever) pretty much meaningless. If you are calibrating (as defined by ISO) then say so and do so. If you are adjusting your instruments for some other reason and without using a measurment standard (why?), then say so but don't use the word "calibration". Remember that the calibrated measuring instruments, when properly used, are your eyes into the process - they are supposed to be showing you what the process is doing. If they are telling you something you don't like, adjust the process, not the instruments. The situation described by Edward sounds like an operator's performance check of a process, and is meaningful only if there is a calibrated and correctly used method of measuring the actual pressure. But a performance check is not a calibration. It is a repeatable method, ususally using calibrated measuring instruments, of verifying that the process is producing acceptable product.

> ...calibration is always a documented method of verifying the performance of a
> measuring instrument, usually under controlled conditions, and always by
> comparing it in some way to a specified standard.

It's a comparison to a 'defined' standard - I agree 100%.

Graeme,
I take all that, and agree with it all. Also, with Marc's statement that calibration is to an accepted standard. But I'm coming at this from a different point of view altogether, and it is, I believe, a point of view which should be accepted as a basic principle, ie; "We set out to become compliant to a 'Standard'. We can only do that when we know what that 'Standard' is. The 'Standard' is described in a limited document, limited, that is, to the words written within it's pages". If that principle is not accepted, then we are open the attentions of unscrupulous people whose interest is only in using the standard as an opportunity to generate cash. I can fall back on the dictionary meaning and uphold my case in any court but if it comes to pitting my definition against your definition, then I'm never sure where I stand and a guy can walk in any day of the week and tell me that I've got it wrong.
That's no good to me. I need to know where I stand. I need to know when I'm right. It's my job. It's what I get paid for. My clients need it as well.
Having a standard that is open to interpretation is a contradiction of terms. It also helps to bring the standard into disrepute and make it an expensive and valueless burdon. And that really riles me. I care about this standard.
rgds, John C

Could anyone tell me where I can find "exact definitions" for both calibration and verification? I've found some, but they're quite different. NIST and CENAM (Mexico) show only the services they offer.

Thank ya all for your help.

Adios.

Thanks for your help. I agree that calibration is a compairsson to a higher standard. What about verification?. Is an specific definition for this word in ISO; I've seen this word as a part of calibration definition. Actually, our quality system enounces both as if they were different.
Gracias de nuevo.

In the link I gave above, I think verification is discussed. Verification is where, for example, someone checks their ESD wrist strap. They're not calibrating it, just verifying it is within tolerance. The cal lab does calibrate the wrist strap tester.

Another might be tape rules in some shops. They have folks compare them to a steel ruler on the wall once a month, for example. That's verification.

Adjustment = Calibration
No Adjustment = Verification

Adjustment = Calibration
No Adjustment = Verification

Marc,

I used to think the same thing, and write my systems using this approach. Then I had a gaging wiz for an auditor who informed me that the key was traceability, not necessarily adjustment. If the "verification" was done with a traceable standard, it qualified as a "calibration".

I found this more than confusing, but if you consider what the cal houses do, it kind of makes sense. If they check the gage with a traceable standard and its OK, it's still considered calibration. If they make an adjustment, they check again after to make sure the adjustment was correct. Now it's an adjust and calibrate.

I still don't have clear in my mind what verification is with the possible exception of a check without traceability (perhaps only in terms of the paper trail).

BTW, even though I had that discussion with that auditor and came away from it confused, I still consider and write systems using the thought process that you describe.

Dan,

I recently had an SGS auditor inform me that verification is a check of the instrument done outside of the normal calibration system. i.e. Scales are calibrated on quarterly basis. Every morning an operator uses a "weight" that is close to the mid point of the normal operating range of the scale to assure that the scale is "within tolerance". A simple record of who, and when is kept. If the scale is "in tolerance" nothing happens. If the scale is "out of tolerance", calibration services is notified. Tolerance is defined as something less than the actual tolerance range of the scale.

Regards,

Rick

Yeah - I understand your qualification of my simple equation.

I've never had a problem with this with a registrar. I advise clients to avoid the word 'verification' with respect to calibration in any documents and in their 'local language'. It's just not worth a pissing match with an auditor over the definition of the word 'verification' with respect to calibration.

Considering the calibre of quality professionals who make up these forums, and considering how few can articulate the differences with accompanying majority concurrence (as you said, even you are still 'confused' about the differences, it's obvious that the gray area is not going away.

Actually, my perception is anything other than an ajustment is a verification.

For the heck of it, here's the dictionary definition of calibration:

1. to assign, verify, or correct the graduated markings on (a quantitative measuring instrument such as a thermometer).

Here's for verification:

Definition 1. the act of verifying.
* *Crossref. Syn. * confirmation
Definition 2. the condition of being verified.
* *Crossref. Syn. confirmation
Definition 3. a formal act or statement that confirms the truth or correctness of something.

That's how I understand it, Rick. But again, I've seen so many auditors who want to get into a definition derby it isn't worth using the word 'verification'. It's easier to say the employee is 'doing a daily check' or such.

This is what I get from reading Q9000:2000 definitions:

As I understand it:

"Verification" - is
Confirmation by providing "objective evidence" that a specified requirement has been met.

"Confirmation" itself can be any of the following activities.
1) Recalulating tolerances
2) Comparing a new design spec with a
similar one
3) Testing to demonstrate results
(functional or destructive)
4) Reviewing documents before they are used.

[This message has been edited by Jim Biz (edited 02 March 2001).]

Here are the definitions I have
1)From MDC (Management Developig Center):
- Calibration: Comparisson to a standard
under specified
conditions
(temperature and humidity)
- Verification: Comparisson to a standard
without taking care of
environmental conds.
- Adjustment: Set an instrument back to
acceptable measuring readings
either verification or
calibration need to be
performed.

2)From our ISO administrator:
- Calibration: Comparisson to a higher
standard within all the
instrument range.
- Verification: Comparisson to a higher
standard in one specific
value.
- Adjustment: Set an instrument back to
acceptable measuring readings
either verification or
calibration need to be
performed after any
adjustment.

As you can see adjusting is different than calibrating.
Marc, on december 26,2000 you posted:
"...calibration is always a documented method of verifying the performance of a
> measuring instrument, usually under controlled conditions, and always by
> comparing it in some way to a specified standard.
It's a comparison to a 'defined' standard - I agree 100%."

and now you say :
Adjustment = Calibration
No Adjustment = Verification.

I think is like Bible, everyone accepts is true but there are different interpretations.

Regards.

Heck, from the way this thread is going it looks like we're all right until the auditor says "No you're not!" http://www.16949.com/ubb/smile.gif

Bubba,

Would you tell us your opinion between calibration and verification?

Not a loaded question, a clarification question!:)

Al,

From what I have previously read on these boards, that question does seem a little loaded. However, I am happy to give you my take on it.

The definition of calibration that I use is:
The set of operations which establish, under certain conditions, the relationship between values indicated by a measuring instrument or system, or values represented by material measure, and the correspoinding known values of a measurement standard.

IMHO, this definition includes those operations commonly known as verification because the values obtained by the measurement instrument, system, etc. are still being corresponded to the measurement standard, whether or not anything is being adjusted.

So, the answer to your question could be summed up in this statement. Calibration includes any activity that establishes the relationship of values between a standard and unit under test, which includes BOTH adjustment and simple verification. I hope that clarifies what you needed.:)

I don't believe that I've thrown my log (twig, whatever) onto this calibration/verification fire, so here goes:

According to NCSL-I and every ISO 17025 assessor that I've spoken to the (paraphrased because it is very late and I should be asleep) definitions are essentially:

Calibration: The act of comparing a known to an unknown to determine difference from nominal.

Verification: The act of comparing the results of the calibration against an accepted standard.

In other words...

Calibration: I measure your widget and find that it is 3 units greater than the standard widget, which is 1 unit less than nominal, then your widget is 2 units greater than nominal.

Verification: According to ANSI B89.1.X, the tolerance of your widget is ±5 units, and my widget is verified to be within tolerance.

Super ultra-simplified:

Calibration is the act of comparison to the standard, verification is the act of accepting/rejecting based on the calibrated deviation.

But then again, this was a few months ago, and the accepted definitions have probably changed twice since then.

Ryan:frust:

:bonk: Did we get this figured out? :thedeal:

according to Agilent Tech;

Popular opinion being that verification is a quick-check of performance perhaps made without any real traceability, whereas calibration provides genuine assurance that the product really meets spec.. In fact, the International Vocabulary of Metrology (VIM) defines verification as being calibration plus evaluation.

Calibration is simply the process of comparing the unknown with a reference standard and reporting the results. For example:
Applied= 1.30V, Indicated= 1.26V (or Error= -0.04V)
Calibration may include adjustment to correct any deviation from the value of the standard.

Verification, as it relates to calibration, is the comparison of the results against a specification, usually the manufacturer's published performance figures for the product. (e.g. Error= -0.04V, Spec= ±0.03V, "FAIL"). Some cal labs include a spec status statement on their Certificate of Calibration. (i.e. the item did/did not comply with a particular spec).

Where no judgment is made about compliance, or correction has not been made to minimize error, it has been suggested that Certificate of Measurement would be a more descriptive title to aid recognition of the service actually performed. Some suppliers also use Certificate of Verification where no measurements are involved in the performance testing (such as for certain datacomm/protocol analyzers), rather than Certificate of Functional Test as this latter term is often perceived as simply being brief, informal checks as might be performed following a repair (often termed "operational verification").

Verification can also relate to a similar evaluation process carried out by the equipment user/owner where the calibration data are compared to allowances made in the user's uncertainty budget (e.g. for drift/stability between cals) or other criteria such as a regulation or standard peculiar to the user's own test application.

Verification is not intermediate self-checking between calibrations. Such checks are better termed confidence checks, which may also be part of a Statistical Process Control regime. The results of confidence checks may be used to redefine when a "proper" calibration is required or may prompt modification of the item's working spec as assigned by the user.
-http://metrologyforum.tm.agilent.com/cal_or_verify.shtml

according to SP Swedish National Testing and Research Institute

Verification is an investigation that shows that specified requirements are fulfilled.

Calibration is a set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument (or values represented by a material measure) and the corresponding values realised by standards.

The result of a calibration may be recorded in a document, e.g. a calibration certificate. The result can be expressed as corrections with respect to the indications of the instrument.

Calibration in itself does not necessarily mean that an instrument is performing in accordance with its specification.
-http://www.sp.se/metrology/eng/terminology.htm#Calibration

and according to VIM; <i>(International Vocabulary of Basic and General Terms in Metrology)</i> or <i>(Vocabulaire International des Termes Fondamentaux et Généraux de Métrologie)</i>
calibration
set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding values realized by standards
NOTES
1 The result of a calibration permits either the assignment of values of measurands to the indications or the determination of corrections with respect to indications.
2 A calibration may also determine other metrological properties such as the effect of influence quantities.
3 The result of a calibration may be recorded in a document, sometimes called a calibration certificate or a calibration report.

personally, I think we can rely on VIM. I don't know why but I think it is a standard that focuses on the definition on Metrology.

I know this post is like several years late but...cheers! :vfunny:

Hey now, that's what I said, but they do use prettier words. I'm going to have to work on that...

Ryan

Lord Ituralde said:

I know this post is like several years late but...cheers!:vfunny:

It was worth the wait, your Majesty! Excellent:bigwave:
:ko: :smokin:

I am new to the cove, but I am hooked. We are a QS-9000 company and have struggled with the "calibration" vs. "verification" issue many times. I have a question:

Suppose the calibration technician has identified a measuring device in production as out-of-calibration. An electronic or maintenance technician adjusts the device using the manufacturer's manual. The cal tech then "verifies" that the device is within required limits using a primary standard.
Is the action taken by the electronic or maintenance tech a pert of the calibration or is it considered "repair"? Did the cal tech "calibrate" or "verify?

Quite the range of definitions...I'll give you one more direct from our assessor.

Verification: The process of verifying a piece of equipment is within tolerance between scheduled calibration.

Soooooo...If I send out a micrometer for yearly calibration, any checks I make on that micrometer during the year are considered verification.


As of now, all my calibration procedures covered under my proposed scope of accrediation will now be changed to verification procedures. Heck of a way to get out of calculating uncertainties, but it'll sure save my :ca: down the ISO Road.

I posted a question on June 18 and never got a reply. If there is anyone out there with an opinion, I'd love to hear it.

We have been told by one registrar that our company has a Calibration Lab and we need to have a scope, etc. We have been told by another registrar that based on what we do, it should not be classified as a Lab. At any rate, we are attempting to write scopes for all of our locations that have "verification" or "calibration" functions. Here are the questions that have been raised along the way:

Suppose the calibration technician has identified a measuring device in production as out-of-calibration. An electronic or maintenance technician adjusts the device using the manufacturer's manual. The cal tech then "verifies" that the device is within required limits using a primary standard.
Is the action taken by the electronic or maintenance technician a part of the calibration or is it considered "repair"? Did the cal tech "calibrate" or "verify"?
Does the technician have to have "appropriate background and experience"?

Sandra,
I would consider correcting the device calibration. Checking it and not having to adjust it is verification to me because you are verifying it's accuracy to the standard. The lab tech should have appropriate background & experience.

IMHO - The adjustment made by the maintenance technician is repair. The verification by the Cal tech, which should include all the appropriate documentation and records of maintenance, is in this case "calibration". I use the term "calibration" whenever there is a record in the calibration data records. For checks on the floor which have no documentation, I use the term verification. This may not be the correct usage, but for in-house terminology everybody understands what you are talking about.

Everybody who is assigned to "calibrate" or perform maintenance on a device should have the appropriate background and experience.

Dave

I would say that the whole calibration process includes the initial check against known standards, any subsequent adjustment, and then any re-check.

Everyone involved in this process (and any other process for that matter) would require appropriate background and experience - but relevant to the part of the 'calibration' they were undertaking. So your technician who merely adjusts the device does not need specific 'verification measurement' experience, or what some might call 'calibration' experience if thought of in the narrow context of measurement alone.

Just my very humble thoughts.

So your technician who merely adjusts the device does not need specific 'verification measurement' experience, or what some might call 'calibration' experience if thought of in the narrow context of measurement alone.


I would hope this technician has more than just a glancing understanding of calibration / verification. To adjust is one thing...to understand how and when and to what is another.

Ken

Sure thing - I was assuming he was adjusting the device under the 'control' of the calibration engineer - as was seemed to be the case in the original question posted.

I have to go with Dave on this one. If you are separating out activities, adjustment is a repair (or corrective) action, and quite often requires root cause analysis, effect analysis, and even product recall. The act of comparing an unknown (the measuring device) against a known (the standard) is the definition of calibration. Verification is the act of using the data from calibration (or in-service check) to determine suitability for a task.

All of that said, IMHO, it is best to use whatever terminology makes sense in your facility. The last place I worked could not deal with the concept of the standard definitions. To make life easier, I used the terms that had been part of the company culture for over 40 years in the quality manual and procedures, and included a glossary that defined OUR use of the terms. No assessor that we encountered (or they continue to encounter) has any problem with it. It is much easier to write a glossary that cross-references terms to the widely accepted norms than to change a group vocabulary to those norms.

As to whether or not you have a "Lab", if you are performing calibrations (comparing devices to a standard) you have a lab, regardless of whether it has doors or if it is a corner of the shop floor.

Ryan

Here's a specific question for you all.
I work in a manufacturing facility.
We have packaging lines that fill bags with product.
Our scales are calibrated monthly, by an outside vendor, using weights that are NIST certified.
Daily, we perform, what we call "verifications" of the scales.
Which is we verify that the scale is still functioning properly. We do this by placing a 50lb weight on the scale to see if it still reads 50lbs. These weights are not traceable to any standard.
During a recent audit, the auditor informed us that we needed to use weights that are traceable to a standard, and not just any old weight.
I told him that we are performing verifications, and not calibrations, therefore we didn't need to. He disagreed. His arguement was that we were making go/no go decisions based on these "verifications", therefore the weights needed to be traced to a standard.
FYI - If a scale failed our daily verification test, we take it out of service and utilize another scale until the scale in question can be calibrated.
So... here's my question:
Do I need to use weights that are traceable to a standard, when performing these daily verification tests?

Shannon,

I'd fight that. For your in-house verification/calibration status check activities, you can use whatever you deem necessary for your system. For CALIBRATION purposes, I'd agree that traceable standards are needed, but the standard does not paint you into a corner as far as verification/calibration status check activities are concerned (assuming YOU didn't paint yourself into that corner by stating you would always use traceable standards for verification in your own QMS).

In our lab, we do happen to use traceable weight standards to verify calibration status on our scale/balance sets. Out in parts of the plant that either smelt or package finished product, we don't though. One thing we have taken to doing is this: when our 3rd party calibration vendor comes in to calibrate scales, when they've finished the job, we put our in-house verification weights on the scale and note the weights for our system. We always do this when introducing a new test weight into the system, and use that recorded weight as the "true" value to verify against. Our registrar has even suggested we do this with our lab test weights, and save ourselves some $$ on having a calibration lab certify our test weights every year.

Shannon,

Are you recording the values from your verification checks? If you are, and if your scale has reasonably good sensitivity and resolution, you might be able to turn the verification into an actual SPC program for the scales and without having your weight calibrated. I am making two assumptions here -- that you do one verification per day, and that your scale calibration vendor has 50 lb. as one of the test points.

Record the readings from your daily checks.
Decide on a rational subgroup - if you work Monday-Friday then five days should be about right. :)
Plot the data on an X-bar/R control chart in subgroups of 5 (or whatever you decide, but not less than 3).
When your scale is calibrated, compare the 50 lb calibration data to your chart. (You may want to actually plot it separately on the control chart.)
As an additional check, plot the 50 lb calibration data over time on a trend chart.
There you have a possible solution -- an in-house SPC program for the scale with regular calibration and direct comparison to a traceable weight!

This should work even with some variations in the plan, and it can be extended to additional scales. It is important, thought, that each scale has its own chart even if the same weight is used for all of them. (Each scale is a different process.) Another refinement would be to measure your weight a number of times (3 to 5?) immediately before the scale is calibrated and again immediately after the calibration. The averages will give you a way to compare the mass of your weight to the one used for calibration, and the standard deviations can give you an indication of the repeatability.

With this type of plan, the actual value of the SPC check standard (a new name for your verification weight?) should be at a calibrated point on the scale, but that does not matter as much as its stability and repeatability. The traceability of measurements made with the scale is taken care of by the calibrations. Regular use of the check standard with recording and charting the data measures the behaviour of the process (the scale) in between calibrations. Just be sure your check standard weight is "controlled" -- kept clean and protected from damage, and only used for the scale verifications.