Gage R & R on Visual Inspection using the Cross Tabulation Method

brandieb1230

Involved In Discussions
#1
Hello!

I am working on conducting my first gage r & r on a visual inspection. I am using the cross tabulation method and the template I have is using 3 operators 3 times 30 parts. Is this required?

I am hoping to use 3 operators, 3 times, 20 parts (6 bad-14 good).
 
Elsmar Forum Sponsor

howste

Thaumaturge
Super Moderator
#2
Re: Gage R & R on Visual

Hello!

I am working on conducting my first gage r & r on a visual inspection. I am using the cross tabulation method and the template I have is using 3 operators 3 times 30 parts. Is this required?

I am hoping to use 3 operators, 3 times, 20 parts (6 bad-14 good).
In the MSA manual page 40 it says:
Sample Size

The question always arises: “How many samples should be used in the study?” To the dismay of most people, the answer is “enough”. The purpose of any measurement study (variables or attribute) is to understand the properties of the measurement system.. A sufficient number of samples should be selected to cover the expected operating range (see also Chapter II Section C). With attribute measurement systems, the area of interest are the Type II areas (see Chapter I, Section B). If the inherent process capability is good (i.e., large Cp, Cpk or Pp, Ppk) then a small random sample may not have many (or any) samples in this area. This means that as the process capability improves , the required random sample for the attribute study should become larger).
The short story is that there is no number specified. If you use a small sample you should use statistical principles to justify your sample size. You should expect some questions if you only use 20 parts.

FWIW for most attribute studies I've seen 50 parts used.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#3
Re: Gage R & R on Visual

If you are trying to comply with a Customer requirement and the template was supplied by them, I would stick to the template.

If you are trying to really understand the effectiveness of the visual inspection, then you might find this paper helpful it has a section for categorical data (visual).

A couple of points:
there is really not much value in doing the inspection 3 times for each operator & part. (other than complicating the calculations) 2 times more than sufficient.
There is a LOT of value in increasing the number parts at 20 or even 30 parts operators can remember and that really skews your analysis. The paper includes a two step process but in summary, the critical elements of the study design are that you include parts at the 'cutoff' (marginally good / marginally bad) and that the defect rate in the sample is equivalent to the defect rate being experienced in real life.
 

Ron Rompen

Trusted Information Resource
#4
Re: Gage R & R on Visual

I agree completely with you Bev, when you say that there is really not much value in doing the inspection 3 times per inspector instead of two, and that additional samples have much more value, inparticular if they are borderline/cutoff samples.
The difficulty that I have encountered in the past is with customer requirements that are on a checkbox list; I'm sure you know the type:
GR&R done? Y/N
'n' samples? Y/N
3 operators x 3 trials per operator? Y/N
GR&R < 10%? Y/N

Too many SQA's and program managers these days dont really understand what they're looking at - they only have a shopping list to go by, and if you don't have all the items on that list (whether they are relevant or not) then you are not going to be approved.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#5
Re: Gage R & R on Visual

Too many SQA's and program managers these days dont really understand what they're looking at - they only have a shopping list to go by, and if you don't have all the items on that list (whether they are relevant or not) then you are not going to be approved.
the dumbing down of the quality profession

that's why I started with the disclaimer about customer requirements...and why I got out of automotive and aerospace so long ago :)
 
Thread starter Similar threads Forum Replies Date
P Gage R&R on Visual Inspection Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 15
G Thoughts on Audit Finding for not doing Gage R and R for Visual Inspection Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 8
Sean Kelley Gage R&R for Visual Inspection for Sheet Steel Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 6
B Visual Inspection (Attribute Data) Gage R&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 27
elkel Reference Only on Gage or Visual Aid Calibration Frequency (Interval) 4
N Example of how to perform a Visual Attribute Gage R&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
O 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
E Functional Gage for TOP applied at RFS Design and Development of Products and Processes 5
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
apestate Inexpensive Gage Blocks for small aerospace startup shop General Measurement Device and Calibration Topics 1
F Position tolerance check gage manufacturing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 8
B Informational Expanded Gage R&R Analysis using Minitab Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 18
S Interesting Discussion Threaded ring gage calibration and tendonitis in the elbows General Measurement Device and Calibration Topics 8
A Federal 700B-26 Gage Block Comparator is not reading properly General Measurement Device and Calibration Topics 0

Similar threads

Top Bottom