"Too little" variation in gage R&R

H

Hamlet

#1
Dear Sirs;

I was starting out to perform a simple gage R&R study on a digital vernier gauge, used in our incoming inspection to control some metal parts from a new supplier.
Now, since I have only received one batch so far, of app. 2.000 pcs., I really do not have any ?Historical process data? to rely on in terms of determining the STDV to be used for calculating the performance in terms of ?assessing the process performance? - and more so: The characteristic that is critical to our production, (- to be measured with the vernier gauge in question), is the width of the parts, stamped out from standard sheet metal - which obviously results in an extremely low STDV if I let MiniTab estimate the value from the study alone.

Better do the example to clarify:

Nominal part width: 3,35 mm.
LSL: 3,42 mm
USL: 3,30 mm
Study: 10 items, 3 appraisers, measurements x 2.
Result: 60 measurements in all; approximately 30 x 3.35 mm and 30 X 3,36 mm, almost perfectly distributed.
Tolerance variance: Perfect ! (Around 8-9%)
Study variance in terms of the ability to "assess process performance": Totally through the roof? (70% or more?) which is probably due to the low STDV calculated by Minitab, (0.002), which is low alright, but nevertheless plausible hence the stamping process if you were able to obtain data from a long term production.

Obviously the problem is how to demonstrate the R&R as well as the ability to monitor process variance - but how the heck do I do this with a digital vernier gauge ? - which by the way, is far within the 0.2 acceptance criteria, and the actual measurements only vary one single increment?
Would it be OK to simply set a higher STDV for the study ?
Or should I just explain - if anyone asks that is - that I really do not care for the ability to assess the process performance, since I am only interested in demonstrating the reproducibility and repeatability of the measuring equipment in order to ensure the conformity of parts in our incoming inspection ?

Any good advise would highly appreciated?
 
Elsmar Forum Sponsor

Miner

Forum Moderator
Staff member
Admin
#2
Since this gauge is used in receiving inspection, will it only be used to assess product to specification? That is, you do not intend to use it for SPC or capability studies?

If the gauge is only used for inspection, you need only worry about the %Tolerance metric. %Study Variation and ndc do not matter unless you intend to use the gauge for SPC or capability studies.

See my blog on MSA, particularly parts 5a and 5b for more detail.
 
H

Hamlet

#3
Hi Miner;

Thank you so much for clarifying ! I had a hunch that the answer was that simple, but I was not sure.
As recommended, I just took a glance at your fine blog, where a another thread also confirmed the fact that %tolerancerVar has to do for incoming inspection.
Still, I know that I will probably face another challenge soon, when I have to perform a R&R on a Zeiss CMM running SPC on an extreeeemely stable process? - but that?s another story.

Thanks again..!
 
Thread starter Similar threads Forum Replies Date
somashekar Too much data, Too little analysis - Manual Stages Assembly Shop Data Collection Quality Tools, Improvement and Analysis 2
Marc GM to place more emphasis on hybrids - Too Little Too Late World News 0
M Do I Expect Too Much of Job Candidates? Career and Occupation Discussions 33
M Informational From RAPS – Another Notified Body Bows Out Ahead of EU MDR: ‘Investment Too High’ Medical Device and FDA Regulations and Standards News 2
M Informational FDA Panel: Too early to pull textured breast implants over cancer risk, need more data Medical Device and FDA Regulations and Standards News 0
F Looking for a Japan MAH recommendation that is not too expensive Japan Medical Device Regulations 4
S FDA Inspections and Pest Control - Pallets too close to walls 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 15
D IATF 16949: Do we have too many processes? Are they all the same? Registrars and Notified Bodies 7
L Nonconformity's risk is too low, so don't report it? General Auditing Discussions 25
O Is the Quality Objective for Company-wide Training as >90% too high? Training - Internal, External, Online and Distance Learning 4
J Thread Gauge Calibration Failure for Pitch Diameter being too large General Measurement Device and Calibration Topics 3
K Too Simple an Internal Audit Check Sheet? Internal Auditing 10
GStough Rejecting a Supplier's Corrective Action Plan When It's Too Weak Supplier Quality Assurance and other Supplier Issues 22
B Is the ISO 13485 auditor being too picky concerning CMDCAS? ISO 13485:2016 - Medical Device Quality Management Systems 5
J Sourcing a Sterile Product - Asking for supplier for too much regulatory stuff? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 2
Q Reduced Device License Fee was rejected for being sent in too early Canada Medical Device Regulations 2
N Calibration Lab unable to issue Accredited Certificate when error is too high? General Measurement Device and Calibration Topics 3
J ISO13485 File-Index getting too large Document Control Systems, Procedures, Forms and Templates 2
N Boss is too hard on me.... Career and Occupation Discussions 48
C How to Write Procedures without too many Details ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 17
L How to deal with too many CARs (Corrective Action Requests), PARs (Preventive Action) Nonconformance and Corrective Action 25
Sidney Vianna The frequent flyers that flew too much... Unlimited AAirpass Coffee Break and Water Cooler Discussions 11
B Management Review Meetings too Long - How to Shorten and Improve Effectiveness Management Review Meetings and related Processes 7
B NAFTA Requirements - Finished Product or Materials/Parts from Suppliers, too? RoHS, REACH, ELV, IMDS and Restricted Substances 2
A When a Company is Too Big for Quality Service Industry Specific Topics 20
C ARGH Too Many Internal Audits Internal Auditing 22
Q Document Control Procedure - Too much detail? Document Control Systems, Procedures, Forms and Templates 8
G Histogram Interpretation when a process is "running too high" or "running too low"? Quality Tools, Improvement and Analysis 4
B Can the Variation on Data be too small in a Variables Data Gage R&R Study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
A Customer SQE - Within Specification but too much Variance Customer Complaints 7
A What to do when customer requirements are too much? Quality Manager and Management Related Issues 29
A Are Risk Analysis Studies required only for devices, or other processes too? ISO 13485:2016 - Medical Device Quality Management Systems 11
R MSDS Sheets for Products - How much is too much - Or is there ever too much? Occupational Health & Safety Management Standards 12
BradM Definitely too old to Trick or Treat Funny Stuff - Jokes and Humour 0
Jim Wynne Is this ISO 9001 Registration Scope Statement Too Vague? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 19
J Late CA (Corrective Action) excuse or I'm too important or no response Nonconformance and Corrective Action 19
4 Change Control Systems - How much is too much? Document Control Systems, Procedures, Forms and Templates 10
Q How much detail in DHR (Device History Record) is too much? US Food and Drug Administration (FDA) 3
J The Dude abides, and this weekend Hub ?Lebowski? fans will, too Coffee Break and Water Cooler Discussions 2
Q Issuance of Corrective Action - Too many related to safety ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
Sidney Vianna Too many competing schemes for "approval of responsible recyclers"? ASQ, ANAB, UKAS, IAF, IRCA, Exemplar Global and Related Organizations 0
R Audit N/C - Quality Policy too generic? AS9100, IAQG 9100, Nadcap and related Aerospace Standards and Requirements 7
Jim Wynne Another way to tell that you've got too much money Coffee Break and Water Cooler Discussions 16
Randy I got a new ride too! 1990 'Vette Coffee Break and Water Cooler Discussions 50
J How to know how many procedures are too many? Document Control Systems, Procedures, Forms and Templates 7
P Improvement Problem - Too few data points and scope is wide Six Sigma 6
pammesue Too Many purchasing/supplier procedures How do I fix them? Document Control Systems, Procedures, Forms and Templates 6
E How would you make an Improvement Plan work? Production is too busy ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 16
Claes Gefvenberg I suppose it was too good to last. Imported Legacy Blogs 10
A Cl 7.5.1: Control of Production and Service Provision - How much is too much? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
Similar threads


















































Top Bottom