

12th July 2006, 03:49 PM


How do I calculate Gage R&R (GR&R) with 1 tester, 1 operator, 3x4 units?
hello all,
I apologize in advance if this is has been hashed out (or so basic it's not worth asking). but i couldn't do a good search to find what i need.
by the way, I'm spankingnew to QA.. and I'm frantically trying to figure out what I'm trying to calculate... so please bear with me.
A customer has asked for GR&R information on our test setup. I think we have data to generate the value, but I have no idea how to calculate it.
1 test equipment
1 operator
3 control units that has 4 channels (essentially 3x4=12 separate measurements per test)
50+ tests (yes. 50x12 data points!)
I can get stdev for each separate channel (have 12 separate stdev). after that, what do I do? also another stupid question is, what unit is GR&R and what does it really mean? (e.g. GR&R=1 vs GR&R=10, 20, etc. I guess I'm sort of looking for a ruleofthumb guidlines like, GR&R=y is ideal, GR&R=z is very bad, etc).
help!
Linda

12th July 2006, 09:24 PM


Re: How do I calculate GR&R with 1 tester, 1 operator, 3x4 units?
You cannot determine GRR with this setup. The best that you can do is determine repeatability, but not reproducibility. Given your criteria, I recommend performing the AIAG Stability study. A calculation shown in this method will provide the repeatability of the measurement system. Is there a reason that you cannot use multiple operators?
GRR results are either 5.15 or 6 standard deviations in the same measurement unit. However, this is typically converted into a percentage of the tolerance (P/T Ratio) or as a percentage of the process variation (% GRR). The rule for these ratios are: < 10% is ideal, < 30% may be acceptable depending on the importance of the characteristic, the feasibility of improving the measurement system, etc. and > 30% is not acceptable.
P/T Ratio is used to determine whether the gage is acceptable for inspection purposes. %GRR is used to determine whether the gage is acceptable for process control, capability studies or process improvement.
Last edited by Miner; 12th July 2006 at 09:30 PM.

Thank You to Miner for your informative Post and/or Attachment!


13th July 2006, 03:53 AM


Re: How do I calculate GR&R with 1 tester, 1 operator, 3x4 units?
Quote:
In Reply to Parent Post by iii_v
hello all,
I apologize in advance if this is has been hashed out (or so basic it's not worth asking). but i couldn't do a good search to find what i need.
by the way, I'm spankingnew to QA.. and I'm frantically trying to figure out what I'm trying to calculate... so please bear with me.
A customer has asked for GR&R information on our test setup. I think we have data to generate the value, but I have no idea how to calculate it.
1 test equipment
1 operator
3 control units that has 4 channels (essentially 3x4=12 separate measurements per test)
50+ tests (yes. 50x12 data points!)
I can get stdev for each separate channel (have 12 separate stdev). after that, what do I do? also another stupid question is, what unit is GR&R and what does it really mean? (e.g. GR&R=1 vs GR&R=10, 20, etc. I guess I'm sort of looking for a ruleofthumb guidlines like, GR&R=y is ideal, GR&R=z is very bad, etc).

You need:
1 test equipment
2 operators, Just see the Templete. See Atachement
Althoug this Version is now Obsolet, The costant has changed, Update it.
10 meassurements times two for Every Operator
By two Operators means 40 meassurents, See templete.

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