Does pitch/increment/resolution of a ruled scale apply to measurement uncertainty as line item?

greif

Involved In Discussions
#1
I have a guy at work that says that the resolution of a lined scale (such as a stage micrometer or steel ruler) should be included as a line item in the uncertainty calculation (because the resolution of the device under test is to be included). While this makes sense for measuring instruments with variable displays, I don't think it does for fixed increment linear scales. He is going to dig up documents that are supposed to back up his position, so I am hoping someone can point me to a specific document (and where in the doc!) that says a linear scale resolution does not apply.

Thanks!
 
Elsmar Forum Sponsor

normzone

Trusted Information Resource
#3
In the absence of any qualified inputs yet, let me play devil's advocate at the moment.

" While this makes sense for measuring instruments with variable displays, I don't think it does for fixed increment linear scales. "

How did you arrive at this conclusion? From my point of view, resolution is resolution, regardless of whether it's analog, digital, or a cubit.

And while we're here, I'll plug a song I like -

 

greif

Involved In Discussions
#4
I guess the main difference is that we are considering the calibration of high quality scales (chrome on glass typically). It is a line standard not a ruler.
Uncertainty calc. Example of why it does not make sense;

(uncertainty line items)
Resolution (of scale) 1mm
Repeatability (of measuring device) 0.001mm
Cal ref std 0.001mm
Meas. Equip cal tol. 0.002mm

K=2 uncertainty from this comes out to be 1.2mm

I am thinking only the resolution of the measuring device should be applied. I need some standard documentation to show this is so.
Help!
 

normzone

Trusted Information Resource
#5
" He is going to dig up documents that are supposed to back up his position, so I am hoping someone can point me to a specific document (and where in the doc!) that says a linear scale resolution does not apply. "

At that point in the game, as usual, the influences to consider are

Industry standards
Regulatory requirements
Organizational procedures

I don't know what team you play for or in what league, but unless there are related requirements in the above three then it's just your preferences vs his.
 

normzone

Trusted Information Resource
#7
Oh, we're talking about what I find ludicrous ...

Well, you did use the words " makes sense ".

For purposes of self preservation I tend to find the world to be ludicrous, so I'm afraid I'm not always the best technical consultant.

But sometimes the area of uncertainty exceeds the information you wish to know. This is what drives us to use different tools, or re-frame the method, or the criteria.

I'd also hoped to draw in a real professional opinion - what is that rule about the fastest way to get the correct answer on the internet is to post the incorrect answer?
 

greif

Involved In Discussions
#8
I had not heard of that particular internet rule; but now that you mention it- very true!

I may have found some evidence to help my case (but nothing as clear cut as "here is the standards doc, and it states such in such at paragraph # xxx".
What I found was a round robin test of a 100mm scale sent to many national metrology centers (doc at: https://www.bipm.org/utils/common/pdf/final_reports/L/K7/EUROMET.L-K7.2006.pdf )

This doc has wonderful descriptions of the machine used, the methodology and the detailed uncertainty stack. Some of the machine are quite similar to our setup (optical microscope to camera to screen). None of them mention the pitch of the scale read!
 

dwperron

Trusted Information Resource
#9
I have a guy at work that says that the resolution of a lined scale (such as a stage micrometer or steel ruler) should be included as a line item in the uncertainty calculation (because the resolution of the device under test is to be included). While this makes sense for measuring instruments with variable displays, I don't think it does for fixed increment linear scales. He is going to dig up documents that are supposed to back up his position, so I am hoping someone can point me to a specific document (and where in the doc!) that says a linear scale resolution does not apply.

Thanks!
If you are using the scale to make a measurement then the resolution of the measurement must be included as a contributor. For instance, if you are using an 8 1/2 digit multimeter to make a measurement but only report out to 0.001 V on your results it is the resolution of the measurement, not the meter, that gets reported.

If you are only reporting your results to the cardinal points on the scale, that is the resolution. If you are interpolating between lines, that is the resolution. Whatever assumptions you make regarding rounding up or down need to be included. The pitch of the gradations should be considered as they might be "significant" in some measurements, and significant is the threshold for reporting uncertainty contributors.
 
Last edited:

greif

Involved In Discussions
#10
I note your words in italics (" then the resolution of the measurement ") and hope that this wording might be a quote of a standard document.
Is it?
This makes my point nicely; we are measuring the scale, and that measurement has an uncertainty. Using the scale to measure has it's own uncertainty.
 
Thread starter Similar threads Forum Replies Date
T What does VW mean by annual requalification? Customer and Company Specific Requirements 1
I Does BSI require suppliers to be ISO 9001 Certified? EU Medical Device Regulations 12
Watchcat Does Regulatory Affairs put the "no" in innovation? Other US Medical Device Regulations 14
Q Does anyone know what this call out means? Manufacturing and Related Processes 3
K COPLANARITY: Composite profile tolerance on multiple surfaces- what does" lower dimensional reference frame tolerance" control? Inspection, Prints (Drawings), Testing, Sampling and Related Topics 11
P Does FDA require certification for quality system internal audit for auditor? Qualification and Validation (including 21 CFR Part 11) 1
H Does anyone has feedback on a notified body for small companies? EU Medical Device Regulations 3
M Does 4.5 - Alternative RISK CONTROL apply to the Particular Standards? IEC 60601 - Medical Electrical Equipment Safety Standards Series 3
E Does IVD need to integrate with hospital IT infrastructure? Medical Information Technology, Medical Software and Health Informatics 2
D What does a level 1 (PSW) PPAP actually promise? APQP and PPAP 16
R GS1 DataMatrix code does not meet GS1 Specification EU Medical Device Regulations 0
M Does the scope of ISO 9001:2015 applies to tenders, pricing and sales department of a medical devices distributor? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
K Why does load cell supplier requires force verification General Measurement Device and Calibration Topics 3
M Does C=0 strictly mean 1 bad, all bad, all the time? ISO 13485:2016 - Medical Device Quality Management Systems 6
C Does a medical device active (zinc oxide) needs BPR registration in EU? Other ISO and International Standards and European Regulations 5
D Does Risk Management apply to re-labeler (MDR) EU Medical Device Regulations 1
Ed Panek Does this FDA Requirement Apply to international (not USA) distributors for USA based manufacturing companies? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 0
S Does anyone have a checklist to prepare for ISO 13485, Stage I audit? ISO 13485:2016 - Medical Device Quality Management Systems 3
S Does a refurbished product required a new UDI? US Food and Drug Administration (FDA) 3
D Change to labelling - does it require a new 510(k)? US Food and Drug Administration (FDA) 5
M What does "constantly" mean ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 13
N Does anyone use SGS for ISO 13485 / CE certification Registrars and Notified Bodies 0
G Does FDA allows remote approvals of quality documentation. Is there any specific guidance on signing any quality records remotely? Document Control Systems, Procedures, Forms and Templates 1
B Does FDA Registration QSR need to cover non-medical devices for contract repackager? US Food and Drug Administration (FDA) 1
lanley liao Does all of the suppliers need to integrated into the supplier list qualified of the company? Oil and Gas Industry Standards and Regulations 2
0 To which part of 13485 does this refer? ISO 13485:2016 - Medical Device Quality Management Systems 3
A Medical Device Contract Manufacturer - Does the CM need to register with FDA? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 3
J Records Control - Does each individual record need to be numbered? Records and Data - Quality, Legal and Other Evidence 2
lanley liao Does the customer`s trademark belong to customer-supplied property? Oil and Gas Industry Standards and Regulations 2
H How does a gas turbine work on diesel fuel? Oil and Gas Industry Standards and Regulations 12
G What does performance specification include? US Food and Drug Administration (FDA) 1
W Where does a coatings and paint company fall in IATF? IATF 16949 - Automotive Quality Systems Standard 5
A How much does a complete biocompatibility test package cost? Other ISO and International Standards and European Regulations 1
B Does anybody know how to get older versions of Minitab to work in Windows 10? Quality Tools, Improvement and Analysis 9
M Does the ISO 9001:2015 standard require a disaster recovery plan or emergency response plan ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 16
C Does an accessory need an IFU if it use is discussed in the Parent device IFU? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 5
S How long does it take to register a product with MHRA? UK Medical Device Regulations 14
M Quality Manual - Where does Revision History Section go? Document Control Systems, Procedures, Forms and Templates 8
U Does *anyone* know a lab that will test to EN 455-4 Medical Gloves shelf life determination? EU Medical Device Regulations 1
A Brexit When does the UK responsible person need to be in place? UK Medical Device Regulations 10
M How does IEC-60601-1 apply to a non-medical device in the patient vicinity? IEC 60601 - Medical Electrical Equipment Safety Standards Series 1
N Does anyone have experience of GB/T 34986-2017? China Medical Device Regulations 1
Z Does anyone have experience with EN ISO 17664 ? IEC 62366 - Medical Device Usability Engineering 9
F Does anyone have an ESD quality/cooler talk to share? Training - Internal, External, Online and Distance Learning 4
A What does this line from MDCG 2020-3 (MDR art. 120 substantial change) mean to you? EU Medical Device Regulations 4
D Change Approval Requirements - Does every change need formal customer approval? Design and Development of Products and Processes 17
T What does AS9100 mean when it says you must establish a process to do X? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 24
L Does a backdate form format can be changed if wrong revision is used? Document Control Systems, Procedures, Forms and Templates 8
B General Motors and Honda Alliance - What does this mean to suppliers? IATF 16949 - Automotive Quality Systems Standard 3
C ISO 13485 :2016 - CAPA - Does every CAPA need to be checked by regulations? ISO 13485:2016 - Medical Device Quality Management Systems 9

Similar threads

Top Bottom