Please teach me!

Kindly teach and explain the following:

1) MSA page 126, 2nd paragraph from the bottom says "The specific gage the team is using has a %GRR = 25% of the tolerance".

Is this gage refer to the go-nogo gage selected to conduct the measurment as listed in Table 12 on page 127? How do we know it is 25%? Is it that we have to conduct using a calibrated master (say gauge block) first to know the % before we use it to do study on page 127?

2) Page 134 on Signal Detection Approach. The estimated %GRR = 29%, but my calculated figure is 0.0237915 / 0.095 X 100% = 25.04%. Why MSA Reference Manual is 29%?

THANK YOU!!

Some small thoughts on this for you.

Page 126 refers to a variable gauge used to select parts that will be used in the attribute gauge study. One would have conducted an R & R study for the determination of 25% of the tolerance range.

I wouldn't worry about signal detection approach since I have rarely, if ever, seen it used. Use the cross tab method but, as I stated before, there is quite a bit of information missing from this standard.

Hi guys,

An alternative way to study the attribute gage such as go no go gage is to use the attribute agreement analysis in the minitab :cool:.

Hi guys,

An alternative way to study the attribute gage such as go no go gage is to use the attribute agreement analysis in the minitab :cool:.

Dear Yew Jin,

The method u mentioned do not need to use or create out of spec parts to conduct the analysis?

The objective is the gage should differentiate between good and bad.

You may collect few bad and good samples in total out 10pcs, randomly identify 1-10. You may use caliper to measure/verify the dimension for that 10sample standard. Do not mention it is good or bad for appraisal to test.
Select 3 appraisals and each appraisal need to test 3 times per each sample.

Compare the results whether they are match with the standard, within appraisal and between appraisals.

Dear Yew Jin,

I understand, even if there are no bad parts, we still could tell whether there are significant difference between appraisers right?

But the Attribute GRR methods in AIAG all ask for bad parts, have we ever try using these methods without bad parts and still can use the result of analysis to determine condition of the gage system?:thanks::thanx:

Dear Yew Jin,

I understand, even if there are no bad parts, we still could tell whether there are significant difference between appraisers right?

But the Attribute GRR methods in AIAG all ask for bad parts, have we ever try using these methods without bad parts and still can use the result of analysis to determine condition of the gage system?:thanks::thanx:

In the end, what's considered acceptable in MSA is up to your customers. When the AIAG guidelines don't make sense in a given situation, it's up to you to discuss it with your customer(s) and come up with a rational and acceptable alternative.

Thank you Jim!:thanks::thanx:

What is an acceptable finding when using the Risk Analysis Method, >90%?

thanks

Does anyone use the Risk Analysis Method when doing GR&R studies on attribute gages?