SBS - The Best Value in QMS software

Calibration is the process of establishing a KNOWN RELATIONSHIP - Traceability

Marc

Fully vaccinated are you?
Staff member
Admin
#1
Subject: Re: Calibration definitions/.../Gazley/Pfrang/Gazley/Pfrang
Date: Mon, 11 Jan 1999 10:01:37 -0600
From: ISO Standards Discussion

From: (Doug Pfrang)
Subject: Re: Calibration definitions/../Gazley/Pfrang/Gazley/Pfrang

>From: "John Gazley"
>
> My comments were not directed to a piece of equipment in which no
> known standard exists
>
> In the case of a gage where no known standard exists to calibrate it
> yes, you are right.
>
> But in the case of something like calipers you must be traceable to a
> known standard. There is a known standard which exists for this gage-
> gage blocks traceable to international or national standards.
>
> If for example you choose to calibrate these with something like a
> piece of bar stock that you control in-house, you must at some time
> calibrate this bar stock to an international or national standard. If
> after this you wish to use this for your calibrations you can. You
> must in some way show traceability to a recognized standard (unless of
> course no known standard exists, then you are free to improvise).
>
> ISO is specific in the case where there is a known standard, you must
> calibrate against certifified equipment having a known valid
> relationship to internationally or nationally recognized standard.
> Unlike many aspects of ISO9000 it doesn't get any clearer or more
> specific than this.
>
> John
>
==============================
Just because you measure a parameter for which an international reference standard exists, does not mean you must have traceability to that reference standard to calibrate a device. It depends on how you use the device. Let's look at a few examples:

1. Let's say I have a prototype of a product I wish to produce. I take my calipers, measure each component of the prototype, and write down all the dimensions of all the components. To make my example easy, let's say I measure a particular part and my calipers tells me it is 5.2 inches long. Then I take that same calipers and I use it to set up my machines to make production parts. I make a batch of production parts, and measure them with my calipers. Each time I measure my production parts, my calipers tells me they are 5.2 inches long. Do I know if these parts meet specification? Of course I do, because they gave the same reading on my calipers, and therefore I know that my production parts are the same length as my prototype part. Do I care if my parts really are 5.2 inches long? No, I don't. All I care is that my parts match my prototype. If I use my calipers in this way, it does not matter if the calipers are calibrated using an international reference standard. In fact, my calipers could be way out of tolerance and they would still work fine in this example. As long as I use the same calipers to measure my production parts as I used to establish my specification, then I don't care if 5.2 inches on my calipers really is 5.2 inches according to some international reference standard; I have "calibrated" my calipers using my prototype as my controlled reference standard.

2. Now, let's extend the example. Let's say that instead of making the parts myself, I call my supplier and tell him that I want a particular part to be 5.2 inches long. He sends me a box of parts, which I measure with my calipers. My calipers tell me the parts are 5.2 inches long. No harm, no foul. We have basically the same situation as above: the parts meet specifications. I don't know if my calipers match some international reference standard, and I don't know if my supplier's calipers match some international reference standard. I do know that my calipers match my supplier's calipers, and that's all I care about.

3. Now, let's say that I get my parts back from my supplier, and my calipers tell me they are 4.2 inches long. Now I have a problem. The calipers I am using really is measuring differently from the calipers my supplier is using. Do I need to use an international reference standard now? Not necessarily.

a. Let's say my supplier is located across the street from my facility. I take my calipers over to my supplier and I explain my problem. He brings out his calipers and we compare them. Sure enough, his always reads one inch longer than mine. (I.e., if my calipers says something is 5.2 inches long, then his says it is 1.0 inch longer -- 6.2 inches long. Thus, when I ask for a 5.2 inch part according to my calipers, he makes the part one inch shorter, because that is what corresponds to 5.2 inches on his calipers. Unfortunately, my calipers measures this part to be 4.2 inches, which is out of specification.) Is our solution to calibrate both calipers using an international reference standard? Not necessarily. Since I know that my calipers reads one inch shorter than his calipers, we agree to use his calipers as our reference standard. From now on, whenever I order parts from him using my calipers, I will add one inch to my specification. That way, we have compensated for the error between his calipers and mine and the readings on our respective calipers will match, even though neither of our calipers is calibrated to an international reference standard.

b. Now, let's say my supplier is located in Taiwan. It is too much of a hassle to ship my calipers to him to compare the two calipers directly, so I decide to calibrate my calipers instead using a reference standard that enables us to compare our calipers indirectly. This is when I use the international reference standard to perform my calibration. By using an international reference standard to perform my calibration, I am using a reference standard that will be the same for my supplier. Assuming he also calibrates his calipers using the same reference standard, then both our calipers will read the same.

Conclusion:

If you analyze each of the above situations, you will observe that the true definition of calibration is simply this: calibration is the process of establishing a KNOWN RELATIONSHIP between (a) the readings on the device which was used to create your specification, and (b) the readings on the device which is used to test conformance to the specification. As long as there is a _known relationship_ between these two readings, the device you use in (b) will be calibrated -- whether or not an international reference standard was used (as an intermediary) to help establish the known relationship. In example 1, the _known relationship_ was obtained because I used the same calipers to create the specification as I used to test conformance to the specification. In example 2, the _known relationship_ was obtained because I again used the same calipers to create the specification as I used to test conformance to the specification, even though I did not make the parts myself. In example 3.a, the _known relationship_ was obtained because I compared my calipers directly to my supplier's calipers. Finally, in example 3.b., the _known relationship_ was obtained using an international reference standard, because I had no other way to establish a known relationship through more direct methods. In each of the examples, my calipers were calibrated; only the situation in example 3.b. required me to use an international reference standard to get there.

And this analysis works for ALL measurement devices, no matter what they are and what the measurement accuracy needs to be.

-- Doug Pfrang
 
Elsmar Forum Sponsor
Thread starter Similar threads Forum Replies Date
D Calibration Process Flow Map Example Wanted General Measurement Device and Calibration Topics 3
C Micrometer and Vernier Caliper simple calibration process General Measurement Device and Calibration Topics 8
S How many of you are using Robotic process automation for calibration lab management? ISO 17025 related Discussions 0
S Measuring a "calibration" process of a machine Capability, Accuracy and Stability - Processes, Machines, etc. 3
R Calibration of processing equipment - 21 CFR 820.70 Production and process controls 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 3
A Internal Calibration Process Suggestions General Measurement Device and Calibration Topics 6
D Calibration Process - What do they mean by "Check Method"? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 2
D ISO/TS 16949 Calibration Control and Process Improvement IATF 16949 - Automotive Quality Systems Standard 7
L Control of Calibration as an Outsourced Process ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
H Monitoring the Calibration Process General Measurement Device and Calibration Topics 13
D Precision Balance Verification and Calibration Process General Measurement Device and Calibration Topics 3
F Process Monitoring Gage Calibration Requirements - 7.6.3.2 External laboratory IATF 16949 - Automotive Quality Systems Standard 1
Q Can a waivers for external calibration labs be implemented via the PPAP process? IATF 16949 - Automotive Quality Systems Standard 3
T Calibration Process QC Laboratory vs. Calibration of Shop Floor Tools ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 17
M How to Internal Audit the Calibration Process Internal Auditing 12
Ajit Basrur Necessity of Calibration of Manufacturing Process Equipment Gages, Controllers, Etc. General Measurement Device and Calibration Topics 7
C Calibration process study help needed - Have I have selected a correct test design? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
S Outsourced Process - Calibration - HELP! ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 6
J Do Process gauges need to be in Calibration control system? QS-9000 - American Automotive Manufacturers Standard 2
U Calculate acceptance of equipment reading after calibration General Measurement Device and Calibration Topics 2
D Question on Documented Calibration versus ISO 17025 Accredited Calibration ISO 13485:2016 - Medical Device Quality Management Systems 0
U Calculate acceptance of calibration reading Measurement Uncertainty (MU) 1
D Air hood calibration ISO 13485:2016 - Medical Device Quality Management Systems 1
K Ground Bond Test for Class I Medical Electrical Equipment - calibration problems IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
E Calibration/Verification Report Durometer ISO 17025 related Discussions 2
S Medical device equipment calibration Qualification and Validation (including 21 CFR Part 11) 1
J Scrap Material Scale Calibration Required? IATF 16949 - Automotive Quality Systems Standard 21
S 7.1.5.2.1 Calibration/Verification Records IATF 16949 - Automotive Quality Systems Standard 6
K Is Calibration Required for Non-Adjustable Commercial Inspection Devices? General Measurement Device and Calibration Topics 11
F Calibration in GPC/SEC General Measurement Device and Calibration Topics 1
Q Changing calibration frequency Calibration and Metrology Software and Hardware 18
M IATF 16949 SI # 10: Integrated self-calibration of measurement equipment- Needs for explanation IATF 16949 - Automotive Quality Systems Standard 2
M Storing Calibration Certificate Document Control Systems, Procedures, Forms and Templates 7
B Risk analysis for defective measuring or measuring equipment out of calibration General Measurement Device and Calibration Topics 2
S Placing a calibration sticker with someone other than your initials Records and Data - Quality, Legal and Other Evidence 8
J IATF 16949 Calibration/Verification records question ISO 26262 - Road vehicles – Functional safety 5
M Approval of Calibration Certificates General Measurement Device and Calibration Topics 1
lanley liao Question regarding the calibration of monitoring and measure equipment. Oil and Gas Industry Standards and Regulations 3
N IATF Calibration Lean in Manufacturing and Service Industries 5
Q Do these certificates of calibration meet ISO 9001 requirements for traceability to NIST? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 12
T Plug Gage Calibration Calibration and Metrology Software and Hardware 1
M Load Cell Calibration using a totalizer on a flow meter General Measurement Device and Calibration Topics 0
E Calibration Records needed ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
D Limited Range Calibration - 5000 lb Industrial floor scale General Measurement Device and Calibration Topics 3
D Calibration of Small Scales General Measurement Device and Calibration Topics 32
C How to Establish the Calibration & Measurement Capability (CMC)? ISO 17025 related Discussions 1
I IQOQ or just initial calibration required? General Measurement Device and Calibration Topics 3
B Calibration in real life ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
J Calibration cycle for monitoring & measuring tools used in medical device manufacturing General Measurement Device and Calibration Topics 5
A Is calibration of test weight required General Measurement Device and Calibration Topics 4

Similar threads

Top Bottom