SBS - The best value in QMS software

Intro to MSA of Continuous Data - Part 9: %Tolerance for One-sided Specs

Miner

Forum Moderator
Staff member
Admin
#1
This is the ninth in a series of articles about MSA. The focus of this article will be on discussing the proper approach to evaluating Repeatability and Reproducibility as a % of Tolerance when the tolerance is one-sided.

The AIAG MSA manual is silent on this and no other "guru" that I am aware of has spoken on it. This is probably because there is no one, right answer.

A recent post asked this question, and I recalled several prior posts that had all asked similar questions, with mixed responses. It forced me to really think the matter through from the perspective of what is the intent of the %Tolerance metric, not what is convenient or easy.
Minitab users have two options. If they enter a natural boundary as the second specification (or the range between the boundary and the specification), Minitab will calculate %Tolerance the same way as if they entered a two sided specification (think Cp). If they leave the other specification blank, Minitab will calculate %Tolerance using 3 * the total R&R and the difference between the study mean and the specification (think Cpk). See the full explanation here.

Lets look a few scenarios, and I will give you my :2cents:. This is not based on any research or statistics, but simply by thinking the problem through rationally.
  • Scenario 1, Maximum Flatness: Zero is a natural boundary and there is a maximum allowable flatness specification. Presumably, there is some incentive to drive for smaller and smaller levels of flatness, thus moving farther and farther away from the USL. In this situation, you will conceivably utilize the entire tolerance spectrum. This would tend to justify using the whole range, or entering 0 as a LSL.
  • Scenario 2, Minimum Hardness: I am using the example used by Minitab in the above link. In this scenario, you are not going to strive for infinite hardness. There will be practical and economical reasons for you to "hover" a safe distance above the LSL, and to not increase over time. In this scenario, it would make more sense to use the Minitab approach. (I will casually overlook the fact that you cannot enter infinity into the USL field).
  • Scenario 3, Maximum activation force: The same logic could apply to a maximum activation force for a push button. If you strove for zero activation force on a conventional spring-loaded design, there would no force left to reopen the switch. Therefore, you will also “hover” a safe distance below the maximum force and not decrease over time. In this case, the Minitab approach of leaving the LSL field blank would also make sense.
It may make more sense to forget about the %Tolerance entirely and use the Gauge Performance Curve approach (see my files MSA 3rd Ed.xls and MSA 3rd Ed ANOVA.xls in my earlier blogs. This approach provides the probability of accepting a product for each specific measurement as you near the specification.

Bottom line, I recommend that you think carefully about your specific situation, and choose the appropriate approach based on the situation.
 
Last edited by a moderator:
Elsmar Forum Sponsor
G

Guest

#3
Does anyone know how to apply and conform with AS9102 when the supplier is using 3D MBD and defining/tracking production efforts in an electronic system? The current situation is that we are having to access multiple "points" in the MES, production planning and extract/print portions that are applicable to a paticular detail part. This process must be repeated for every part of the production planning where the part is modified and the multiple extract, print. compile process mmust be conducted for ever detail part.

In the past, this info was captured in a traveling QA form, so the current process (multiple extracts) is not that different, it's just that we haven't been able to realize any benefits from having MBD or electronic instructions. Has there been any industry research on how this is handled. Any pointers or recommendations would be much appreciated.
 
Thread starter Similar threads Forum Replies Date
Miner Intro to MSA of Continuous Data - Part 10: Creating gauge families Imported Legacy Blogs 10
Miner Intro to MSA of Continuous Data – Part 8: Comparison of Two Gages Imported Legacy Blogs 3
Miner Intro to MSA of Continuous Data – Part 7: R&R using Wheeler’s Honest Gage Study Imported Legacy Blogs 17
Miner Intro to MSA of Continuous Data – Part 6: R&R for Non-Replicable Measurements Imported Legacy Blogs 18
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 5b: R&R Imported Legacy Blogs 14
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 5a: R&R Imported Legacy Blogs 5
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 4: Stability Imported Legacy Blogs 2
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 3: Linearity Imported Legacy Blogs 15
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 2: Bias Imported Legacy Blogs 4
Miner Intro to Measurement System Analysis (MSA) of Continuous Data – Part 1: What and Why? Imported Legacy Blogs 22
T Intro & ISO 9001:2006 Question - Is ISO 9001:2006 Released? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 1
E French Intro to Quality - Introducing ISO 9001 to New Employees Book, Video, Blog and Web Site Reviews and Recommendations 1
Nihls MSA Study Type 2 (special conditions ) IEC 60601 - Medical Electrical Equipment Safety Standards Series 0
Nihls When the MSA results show no operator influence Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
S MSA for attribute relation gage Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
Nihls MSA Study Type 1 (CMM) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
M MSA Study Type 1 not capable. We are at the limit. And manufacturing wants to continue producing. Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 7
I Overwhelmed with attribute MSA requirement for visual inspection IATF 16949 - Automotive Quality Systems Standard 8
H Need MSA 4th ed. compliant attribute MSA template General Measurement Device and Calibration Topics 4
P MSA for titration Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
P MSA - what exactly mean "system" and master sample Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
P MSA study for visual system with artifical inteligence Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
D MSA strategy Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
K Updated MSA with the Annual PPAP validations APQP and PPAP 8
E MSA for Push and Pull test Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 9
6 MSA for Calculated Clearance Dimension Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
Ron Rompen MSA on automated measurement system - Multiple Step Vision System Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
G MSA check list to audit IATF 16949 - Automotive Quality Systems Standard 10
R MSA for ATE (Automatic Test Equipment Embedded Software) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 9
Bev D MSA Tools Misc. Quality Assurance and Business Systems Related Topics 3
R MSA studies for Heat Treatment Equipment Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
C Industrial scales and MSA (IATF 16949 requirement 7.1.5.1.1) IATF 16949 - Automotive Quality Systems Standard 30
M Difference between MSA and MSE? General Measurement Device and Calibration Topics 1
M Test method validation - Is MSA (MSA1, MSA2, MSA3 and linearity) a good solution? Medical Device and FDA Regulations and Standards News 2
A MSA results differences - Supplier results vs. My results Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
R Preliminary MSA and Sockets' correlation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 0
I MSA requirement for 5 Micrometers + CP changes need customer approval? IATF 16949 - Automotive Quality Systems Standard 2
T Correct MSA study for an automated camera system which makes attribute inspection Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
Bev D MSA Misc. Quality Assurance and Business Systems Related Topics 46
Emran.mi Measurement system analysis - Can you help me about implementation MSA for CMM device Manufacturing and Related Processes 2
N MSA Study for a Leak Testing Device Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
N Justifications for not performing MSA (Measurement System Analysis) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
D Do I need part variation while doing Destructive Variable Gage R&R MSA study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 19
Prashant G MSA Study - AS 9100 and and our customer want us to do MSA study for their parts dimension Reliability Analysis - Predictions, Testing and Standards 4
D Compression Spring Force MSA Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
E MSA Study on MTS dynamic rate measurements Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
A The FILE recommended by AIAG MSA 4ed for LINEARITY Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 0
S IATF 16949 Audit MSA IATF 16949 - Automotive Quality Systems Standard 10
C Do Calibration Reference Standards require an MSA study? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
A MSA When an Instrument Measures More than One Parameter Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 7

Similar threads

Top Bottom