SBS - The Best Value in QMS software

Variation (using ANOVA method) Required for Gage R&R

J

jenboy

#1
An argument about variation using ANOVA method - which one is "right"?
1) We need to dial in our blow molded product to the low end of the spec and the high end of the spec to ensure we have the whole range of variation the gage is required to measure.
2) Based on the capability study, control limits are calculated and the range between those calculations are used as the basis for the variation the gage needs to measure.
I'll admit, I'm the number 2 and I'm not the boss. The boss is dead set on number 1. Problem is, if we run to the low side on wall, we're out of spec on weight and run the risk of going out of spec on wall as well. Our charts show us running with a shifted (to the high side), albeit normal curve. (Why the print specs and tolerances weren't revisited before PPAP I have no idea!) I have a die setter ready to explode because he can't dial in what the QA Manager (and acting QE on this project) wants with out producing a bunch of junk - have I been doing this wrong the whole time? I never had a customer question it, or have a gage go haywire. But I'm stuck now with a whole bunch of frustrated program people over a MSA - and a looming PPAP date. Any suggestons?
 
Elsmar Forum Sponsor

Marc

Fully vaccinated are you?
Staff member
Admin
#2
Another quick "Bump". My Thanks in advance to anyone who can help with this one.
 

Miner

Forum Moderator
Staff member
Admin
#4
While we are working out the issue :frust:, I am pasting the relevant section from my blog below.

Part Selection

The first step in an effective R&R study is to determine the use of the gage itself. Will it be used for part inspection to a tolerance, for process control, for statistical studies (e.g., a hypothesis test, capability study, DOE, etc.), or for a combination of these? This is very important because it influences the selection and quantity of parts needed for the R&R study.


If the gage is used solely for part inspection, the selection of parts is not critical because the part variation is not included in the calculation of the R&R metric, %Tolerance (i.e., P/T Ratio). Some will recommend that parts representing the full spread of the tolerance be used. While this does not hurt, it is not really necessary. If a gage linearity study has been performed, the change in bias over the tolerance spread is known. If a gage linearity study has not been performed and there is a linearity issue an R&R study will not detect it.

If the gage is used for part inspection or for statistical tests, the selection of parts is critical because the part variation is part of the calculation of the R&R metric, % Study Variation (i.e., %GRR). It is vital that the parts selected for the study reflect the actual variation of the process. That is, the StdDev of the parts equals the StdDev of the process. Some statistical packages, such as Minitab, allow the entry of the historical StdDev of the process. If your software has this option, use it, entering the process StdDev from a capability study or calculated from SPC charts. If the software does not have the feature, manual calculations using the historical value are still possible as follows"

% Study Variation = 100 * [StdDevR&R / StdDevTotal Variation]

StdDevTotal Variation = SQRT[StdDevR&R^2 + StdDevPart Variation^2]

Manually substitute the StdDev from a capability study for StdDevPart Variation
 
Thread starter Similar threads Forum Replies Date
P Difficulty in Detecting Within Lot Variation when using Zbar W (Normalize) Chart Statistical Analysis Tools, Techniques and SPC 14
N Gage R&R - Using Tolerance method, or part to part variation? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
S % of Contribution or % of Study Variation? Gage R&R using Minitab Using Minitab Software 26
B Combat Low Part to Part Variation in GRR Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 8
E Zero part to part variation - Gage R&R project Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 15
K Analysis variation among the lots during cpk calculation. Design and Development of Products and Processes 1
N Post registration variation to medical device Other Medical Device Regulations World-Wide 1
Q % Study variation low, % tolerance high - GR&R Interpretation help Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
D Variation between Faro Arms Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
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
E Changes to medical device submitted through a variation? EU Medical Device Regulations 1
T GRR based on part tolerance or process variation. Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 7
B Gage R&R Acceptable (10-30%), deduct Total Variation from Tolerance Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 12
J What is the difference between Process Variation and Tolerance? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
D "It depends on the Auditor" Is excessive variation jeopardizing system certification? Registrars and Notified Bodies 40
Q What does % study variation of 20% mean in GRR? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 17
V Query on PA66+GF15% - Color variation (Natural to Yellowish) problem Manufacturing and Related Processes 20
Mikey324 GR&R - Little to no part to part variation in single part number Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 14
K Measurement system analysis "shall be conducted to analyze the variation..." Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
E Measurement System Analysis (With parts that have variation) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
S Variation Study on Mined Material - What do you call it (not a control chart) Statistical Analysis Tools, Techniques and SPC 7
P Total Variation in Data - Overall Importance of the Principal Components Reliability Analysis - Predictions, Testing and Standards 1
GURU SDI Measurement Variation in a Coating Thickness Meter Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
M How to Measure Paper considering Variation and Humidity General Measurement Device and Calibration Topics 10
J Nested Gage RR Accounting for Process Variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
B Gage R&R MSA - Variation, Tolerance, Variance by different methods IATF 16949 - Automotive Quality Systems Standard 23
J Calculating part variation from historic data for GRR study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
I Gage R&R confusion on a part that has little variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
M How do I measure variation in my process ? Capability, Accuracy and Stability - Processes, Machines, etc. 3
B Reducing variation through multiple readings Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
C AS9103 Variation Management Example Procedure AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 1
J Reducing Variation via Multiple Readings Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
V Drift and Variation over Time of an Analytical Balance. Qualification and Validation (including 21 CFR Part 11) 2
T Variation in values of the levels in Factorial/Response surface design Using Minitab Software 1
B Process Control - Selecting Parts - NDC & Study Variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
J Weighing Balance Accuracy for Plastic Moulded Parts variation study Manufacturing and Related Processes 3
A How to understand the source of variability and "stream-to-stream variation" Six Sigma 8
I The concept of Surrogate Process Variation in MSAs Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
Bev D Probability question - Components of Variation study on a single use diagnostic test Statistical Analysis Tools, Techniques and SPC 1
X Poor GR&R results due to Low Part Variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 20
C Design of Experiments to Reduce Variation in a Lathe Operation Quality Assurance and Compliance Software Tools and Solutions 9
M 30% Max Study Variation Criterion - Where Cited? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
D Reducing Within Part Variation during a Gage R&R Study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 26
H "Too little" variation in gage R&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
C Multiple Variation Gage R&R for Automated Testers Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
L DOE (Design of Experiments) - Analyse Variation with Minitab Using Minitab Software 5
S Gage R&R - Percent of Tolerance or Percent of Variation? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
G Crossed and Nested MSA - Determining Components of Variation Using Minitab Software 6
2 DOE to minimize Noise Contributions that enlarge the Variation beyond Part-Part Quality Tools, Improvement and Analysis 5
B Components of Variation not within or between Quality Tools, Improvement and Analysis 4

Similar threads

Top Bottom