How to conduct R&R Study for Runout Measurement & for unilateral toleranced features



R&R Study for Run out measurement

Can any one suggest us how to conduct Gage Repeatability and Reproducibility for RUN OUT measurement with Lever Dial of 0.001mm Least Count. Acceptable limit of Run out is 0.05mm. Whether we can fallow same method as reference in MSA manual of QS9000 as run out checking is with single sided tolerance.
Elsmar Forum Sponsor

David Drue Stauffer

First, is there a special Gage R&R method for unilateral toleranced features? No. The methods are the same, but the interpretation of the data must be treated differently. "Unilateral features may produce "bounded data". Basically, that is any measurement data limited by an upper or lower value (e.g. runout, flatness, straightness, etc. where measurement values cannot be recorded lower than "0"). For example, a highly capable process could produce a diameter with a runout tolerance of .001" max that measures on the average .0002" with occasional measurement values up to .0012". This would be considered a capable process. If we tested the data it would not be normal (bell shaped curve)but appear skewed right.
When we violate the assumptions of any statistical tool, the tool becomes unpredictable and may indicate a false conclusion. What happens to unilateral data that is not normal, but treated or assumed to be normal? The measurement system appears unstable, the Gage R&R error is inflated. It makes the measurement system look worse than it is.
An advanced practitioner of GR&R understands the assumptions of the tool and remains a healthy skeptic (test the assumption). When you know that you are dealing with unilateral or skewed data - test it for normality. If it is normal data, proceed with the standard methods and evaluation techniques. If the data is not normal, you can usually transform it to act normal, then proceed evaluating the transformed data. If you can't transform, proceed with skeptic caution. You will rely on profound knowledge an practical experience with the measurement system.
Certain high-end measurement systems (circular geometry, surface finish, CMM, etc.) are best evaluated using a control chart method and measuring master artifacts on a regular schedule.

Dave S.


I don’t consider myself a MSA guru, but I have been practicing R&R’s now for about 10 years. I must admit, Mr. Stauffer’s previous post made me go back and review the MSA manual. I would like to pose the question, where in the MSA manual does it state that the process must be in statistical control? What relevance is it if the process is yielding a skewed bell curve? The MSA manual does state, “The measurement system must be in statistical control. This means that the variation in the measurement system is due to common causes only and not due to special causes.” Also that data is reviewed to determine “statistical control with respect to repeatability”. But I don’t see where it relates back to process control. Please enlighten me.


If you refer the Section 4 General Guidelines of MSA Manual, The assessment of the measurement system is done in two ways, Phase 1 and Phase 2.
The purpose of Phase 1 is to find the measuring system possess the statisitical properties. If the measuring system is running with Special causes, we cannot predict the system performance over a period of time. Hence, its must we should assess the measuring system is possess appropriate statistical properties.
Phase 2 is done to continously ensure the system is under statiscal (ie., only with common cause), one form of phase 2 testing is commonly by Gage R&R.


I believe I agree. But let me see if I understand this correctly. Phase 1 is broke up into two parts. The first section of phase 1 is to determine if the measurement system possesses the required statistical properties or not. These statistical properties include the determination of adequate discrimination, system stability over time and linearity (among others). The second part of phase 1 is to determine if environmental factors have a significant influence on the measurement system.

Phase 2 in a nut shell is GR&R process.

Now, I am still a little bit fuzzy on how a process (such as the one in second post) with a skewed bell curve could make “the measurement system appears unstable” and the “gage R&R error is inflated”

I always thought the GR&R study was independent of the (manufacturing) process distribution. Process spread is different; the GR&R result will be impacted by the spread of the process if the samples collected represent the entire process range. But what impact will it have on a GR&R study if the manufacturing process has a skewed bell curve or not?

But like I have said before, I am still a young buck in the world of quality with a lot to learn.
Thread starter Similar threads Forum Replies Date
H When to conduct a MSA (Measurement Systems Analysis) study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
M How to Conduct a Machine Capability (Cmk) Study Statistical Analysis Tools, Techniques and SPC 27
E Minumim number of parts to conduct the Process Capability Study APQP and PPAP 18
F 1. Suggest a Gage for Checking Rounding of Gears 2. When to conduct Stability Study? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
Forum Administrator Code of Conduct Elsmar Cove Forum ToS and Forum Policies 0
T How to conduct combined internal audits (9001 and 13485) Internal Auditing 1
I Foreign manufacturer: how to conduct Clinical Investigation? EU Medical Device Regulations 4
E ISO 13485 in Clinical Trial conduct: Applicable or No ISO 13485:2016 - Medical Device Quality Management Systems 2
S Requirement to Conduct New Shelf-life Testing? (re-do testing for design change) EU Medical Device Regulations 3
M Informational US FDA Draft Guidance – Patient Engagement in Design and Conduct of Medical Device Clinical Investigations Medical Device and FDA Regulations and Standards News 0
B Is it necessary to conduct product audit of entire product which is manufactured in the company as per IATF IATF 16949 - Automotive Quality Systems Standard 4
C How frequent to conduct Clinical / Performance Evaluation? CE Marking (Conformité Européene) / CB Scheme 4
S Script of R software to conduct Nested GRR for Destructive Testing Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 0
J ISO 9001:2008 - Can I still conduct Internal Audits in my company? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 7
J Can I conduct Internal Audit for combined ISO 9001, ISO 13485 and ISO 14001? Internal Auditing 37
R How do I conduct my API Q1, ISO compliant internal audits? Internal Auditing 1
P Can internal ISO 17025 Auditor conduct ISO 9001 Audit ISO 17025 related Discussions 7
S CMDCAS ISO13485 - Bilateral agreement with SAI global to conduct Certification Audits ISO 13485:2016 - Medical Device Quality Management Systems 7
S Conduct Customer Satisfaction Survey for every submitted Bid? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
T Conduct a fractional factorial 2^13-5 experiment with Minitab Using Minitab Software 4
M Help me understand how to conduct a Chi Square Test Statistical Analysis Tools, Techniques and SPC 3
N How do I conduct Management Review Meetings? Management Review Meetings and related Processes 34
R Can our Supplier's Quality Mgr. conduct Supplier Audit on behalf of manufacturer? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 4
F Tips, Guidelines and Checklist to conduct Audit of Supplier & Subcontractor Document Control Systems, Procedures, Forms and Templates 5
L How to conduct a Quality Audit based on ASME BPVC VIII-1 requirements Various Other Specifications, Standards, and related Requirements 4
Y FDA - Does anyone have conduct the validation on GR&R worksheet before? Qualification and Validation (including 21 CFR Part 11) 7
I Code of Ethics and Conduct wanted Document Control Systems, Procedures, Forms and Templates 3
C When is the Best Time to Conduct Internal Audits Internal Auditing 22
Q Tips on how to conduct a good Internal Audit Opening Meeting Internal Auditing 19
D How to conduct a Gage R&R on DC Tools to Torque Bolts Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
G How to conduct a Toy Recall (College Question) Customer and Company Specific Requirements 2
N How do I conduct Risk Management for my company? ISO 13485:2016 - Medical Device Quality Management Systems 7
K How to conduct a QCC project Misc. Quality Assurance and Business Systems Related Topics 2
N Tyvek Pouch Seal - Pressure needed to conduct Vacuum Seal Leak test? 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 2
J How to Write the Planned Interval to Conduct Internal Audit, Management Review, etc.. ISO 13485:2016 - Medical Device Quality Management Systems 3
R How to conduct the Threshold Test of Mobile Equipment specified in 3rd edition? IEC 60601 - Medical Electrical Equipment Safety Standards Series 35
S How to conduct Capability Analysis for this data? Statistical Analysis Tools, Techniques and SPC 12
K Can auditors freely conduct confidential interviews, or consent is necessary? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 22
P How to conduct ILCP (inter-laboratory comparison programme) to get ISO 17025 ISO 17025 related Discussions 3
M Do we need to conduct Vendor (Supplier) Evaluation? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 17
K When, whom, how to conduct hazard analysis of PRP?s, OPRP?s and CCP?s? Food Safety - ISO 22000, HACCP (21 CFR 120) 1
S Can a suspended CB still conduct Surveillance Audits? Registrars and Notified Bodies 4
J My mentors insist I use hotel's employee manuals and codes of conduct for my... Service Industry Specific Topics 3
somashekar Sustainability audit per EICC Supplier Code of Conduct Sustainability, Green Initiatives and Ecology 14
Marc Apple Enforces "Supplier Code of Conduct" After Child Labor Discovery After Work and Weekend Discussion Topics 13
B How to Conduct a Review of Customer Order (Contract Review)? Contract Review Process 5
V How many years of experience is needed to conduct the internal audit in my company? General Auditing Discussions 4
Sidney Vianna Can CB's (certification bodies) conduct internal and 2nd party audits? Registrars and Notified Bodies 12
G How to conduct internal audits? Internal Auditing 52
M ISO 17025 Audit check list to conduct horizontal and vertical audits ISO 17025 related Discussions 10

Similar threads

Top Bottom