Gage R&R - Applied threshold for the %EV and %AV values?

S

Star18

#1
Hi everybody,

Is there someone for helping me ? :confused:

I would like to know if someone knows if there is an applied threshold for the value of %EV (Equipment Variation) and %AV (Estimated Variation) in the GRR calculation. How can we explain these two indicators? :bonk:

Thanks in advance. :bigwave:

Rach.
 
Elsmar Forum Sponsor

Jim Wynne

Staff member
Admin
#2
Star18 said:
Hi everybody,

Is there someone for helping me ? :confused:

I would like to know if someone knows if there is an applied threshold for the value of %EV (Equipment Variation) and %AV (Estimated Variation) in the GRR calculation. How can we explain these two indicators? :bonk:

Thanks in advance. :bigwave:

Rach.
"AV" stands for Appraiser variation, not estimated variation. There are no thresholds; the information that comes out of a GR&R study should be used to help target improvement efforts. If EV is disproportionately high it might mean that the gage needs calibration or repair, or that the gage is inappropriate for the application. IF AV is high, it might mean that operators are using the gage improperly (or inconsistently) and might benefit from training.
 

Jim Wynne

Staff member
Admin
#3
Jim Wynne said:
"AV" stands for Appraiser variation, not estimated variation. There are no thresholds; the information that comes out of a GR&R study should be used to help target improvement efforts. If EV is disproportionately high it might mean that the gage needs calibration or repair, or that the gage is inappropriate for the application. IF AV is high, it might mean that operators are using the gage improperly (or inconsistently) and might benefit from training.
I also should have mentioned that "AV" is also referred to as Reproducibility and "EV" as Repeatability.
 

Miner

Forum Moderator
Staff member
Admin
#4
Star18 said:
Hi everybody,

Is there someone for helping me ? :confused:

I would like to know if someone knows if there is an applied threshold for the value of %EV (Equipment Variation) and %AV (Estimated Variation) in the GRR calculation. How can we explain these two indicators? :bonk:

Thanks in advance. :bigwave:

Rach.
While there is no specific threshold value for EV and AV individually, there are threshold values for the combined value %GRR or P/T ratio.

These thresholds are: < 10% ideal, between 10% and 30% acceptable, > 30% unacceptable.

The purpose of breaking it out to AV and EV is to identify the major source of the variation to allow you isolate the cause and reduce the variation.
 
S

Star18

#5
%ev & %av!

Hi everybody,

I understand what you want to mean but my question is about the meaning of a value of %EV and %AV according to the result of %GRR.
You will find as an attached file a form of MSA application. Could you help me please ?

Rach.
 

Attachments

Miner

Forum Moderator
Staff member
Admin
#6
I am not completely clear on your question. Can you be more specific?

I did review the attached file, and can offer some advice on the results. The %GRR = 80% and the ndc = 1.05 both indicate that this gage is unacceptable for use in process control (SPC) or for use in any type of statistical evaluation such as a DOE.

There may be several explanations for this. The first question that must be answered before going any further is: Is the part variation representative of the actual process variation? If it is not representative, you must repeat the study using parts that exhibit the same variation as the process.

If the part variation is representative of the process variation, you then look at the components of variation. The high %EV = 80% tells you that the equipment itself is a likely place to begin looking.

Check the validity of the 10.010 measurement made by Appraiser A, Part 1, Trial 2. Even changed to 10.0001, the equipment does not have sufficient resolution to "see" process variation. This gives you the low ndc value. If the parts are representative of the actual process variation, you will need to invest in a gage with greater resolution.

Before you do this, what are you using the gage for? If you are looking at SPC, do you have an economic case for it. That is, will the benefit of SPC justify the new gage? Are you using the gage for inspection to tolerance? If you are, then calculate the P/T ratio for the gage. This may be more acceptable than the %GRR.
 
Thread starter Similar threads Forum Replies Date
E Functional Gage for TOP applied at RFS Design and Development of Products and Processes 5
C Allowance for Slip Fit - Additional Allowance applied to GO NO GO Plug Gage General Measurement Device and Calibration Topics 26
T Plug Gage Calibration Calibration and Metrology Software and Hardware 1
L Gage R&R TMV Acceptance Criteria Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
S MSA for attribute relation gage Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
E Zero part to part variation - Gage R&R project Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 15
M Gage R&R and right way to measure Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 16
L Gage RandR on automated equipment. IATF 16949 - Automotive Quality Systems Standard 7
B Gage calibration frequency, ISO and IATF - What are the requirements Calibration Frequency (Interval) 3
D Difference between Test Method Validation and Gage R&R Qualification and Validation (including 21 CFR Part 11) 18
R Determining Uncertainty from Gage R&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
C Correct Calibration Method for Dial Depth Gage General Measurement Device and Calibration Topics 6
C Gage Block Wringing General Measurement Device and Calibration Topics 3
B Gage R&R with NDC=1 Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 19
S Type 1 Gage R&R or something else? Reliability Analysis - Predictions, Testing and Standards 6
G Should I perform Gage R&R only at the beginning of a new project? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
V Thread Plug Gage Pitch GO Diameter out of spec AQL - Acceptable Quality Level 8
G Gage R&R - Where am I going wrong? Part of a FAIR submission (Aerospace) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
R Gage R&R Excel templates Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
K Gage R&R with more than 3 appraisers Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
Anerol C Gage R&R Template AIAG 4th Edition IATF 16949 - Automotive Quality Systems Standard 3
T Attributes SPC study - Attributive control (Go gage) Statistical Analysis Tools, Techniques and SPC 5
S Capability or Gage R&R Study for Leak Tester? Reliability Analysis - Predictions, Testing and Standards 15
N % Tolerance - Type 1 study on the gages, then a gage R&R (ANOVA) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
M Definitive answer on Type 1 vs Type 2 vs Type 3 Gage Study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 0
V Gage Management and Gage R&R Software General Measurement Device and Calibration Topics 1
D Gage R&R Study on Load Cells - Large chemical blending tanks IATF 16949 - Automotive Quality Systems Standard 1
B Minitab Type 1 Gage Study on True Position Question Measurement Uncertainty (MU) 1
S Gage R&R on alloy Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 10
8 Need Help - Runout - Function Gage Inspection, Prints (Drawings), Testing, Sampling and Related Topics 7
L Gage R&R studies for identical Devices - Need to confirm the requirement to perform them Reliability Analysis - Predictions, Testing and Standards 2
G Stab Pin Size For Check Gage Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
F No reproducibility Error in Gage R&R? Reliability Analysis - Predictions, Testing and Standards 4
M Template for Attribute Gage R & R wanted Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 3
G Warning about Deltronic Gage Pins - The "Certification of Accuracy" document General Measurement Device and Calibration Topics 13
A Gage type 1 study on CMM Capability, Accuracy and Stability - Processes, Machines, etc. 2
Q Gage R&R for Instant Measurement Machine Manufacturing and Related Processes 6
M Gage R&R with large inter part variance - Torque Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 7
D Do we need normal data for gage r&r studies? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
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
S Gage R&R Standard Deviations Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
J Informational Gage R&R: Swapping operators Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 5
S Gage R & R for large amount of inspections IATF 16949 - Automotive Quality Systems Standard 10
S Ring Gage Thermal Expansion General Measurement Device and Calibration Topics 4
L Gage R&R for test precision or uncertainty prediction? Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
S Minor diameter of threaded ring gage General Measurement Device and Calibration Topics 1
A Does Torque Gage Need Validation? Reliability Analysis - Predictions, Testing and Standards 4
J Ignoring a Failed Gage R&R and upcoming external audit IATF 16949 - Automotive Quality Systems Standard 22
R Scaling a Gage R&R - 2 holding fixtures each with 10 nests 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

Similar threads

Top Bottom