Aumomatic Machine GRR questions
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June 27, 2006 at 12:13 pm #43848
Hello:I have some confusing questions need your clarification regarding the aumomatic machine GR&R.
Our product is a parts assembly.the gap between parts is what we concerns.the product is similar to cylinder type.
the process is operator only need put the product on the machine. then the machine will automatically start the set program and measure the gap. so it is clear that there is no reproducibility here. In this case, how can i proceed GR&R test? 10 samples, 3reps, 1operator?
Another tricky point is: it is a cylinder type product, if we put on different check angle ( from 0deg to 360deg), some samples will have great different value (half of tolerance), some may not. Can we say it is the parttopart variation and will not contribute to Gage R&R?
Your advise and input will be appreciated.0June 27, 2006 at 12:29 pm #139651
sixsigmadeewanaMember@sixsigmadeewana Include @sixsigmadeewana in your post and this person will
be notified via email.I would recommend that you should take the worse possible scenario and do a gauge r&r on it.
Choose 3 different angles that you would commonly use to check the parts. Use 10 parts and check each part 3 times in one location. The 3 different angles will act as 3 operators.
The variation between the readings of different angles for same part is your reproducibility and the variation between different readings at the same angle for same part is your repetability.
If you need more help, post your email address.0June 28, 2006 at 4:02 am #139692hi.sixsigmadeewana, thanks.
1.but how can i choose my samples? does ” the worst scenario” mean picking up the biggest difference sample?2. How to undrstand the result using viewpoint of process improvement.my email address is: [email protected]0July 3, 2006 at 8:09 am #139890I have a very similar problem at the moment. We have an automatic filling machine that does its own dose weight checks. A vial is automatically placed on a weigh cell, then filled and placed on another weigh cell to calculate net weight by difference. Since the machine feed is totally automated, how do I carry out a gauge R&R to determine how good the weighing process is? Is a gauge R&R even a valid tool to do this, or would it be more appropriate to weigh a calibration weight multiple times and do a ttest?
0July 3, 2006 at 8:54 am #139893Louis,
you need to take parts from your whole measurement range so that your part to part variation is big enough to give you valid results. This means select say 6 parts that range from the smallest gap possible to the biggest gap possible.
Then you need to retest each part 2 or 3 times (repeatability), where the parts are cylindrical it is important to make sure the parts are aligned the same way in the machine. Can you mark the parts in some way to make sure the orientation is the same each time the same part is measured?
Sarah
you could carry out a Gage R&R using two or more calibrated weights, again these should cover the range of your measuring equipment or process, this would be a quick test. Alternatively you could carry out the R&R using two or more different products that have different mean weights and run the test as though it were a destructive test. In this case you assume that each part is identical within the batch but you have a large variation between batches.0 
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