How to determine Equipment Tolerance Variation - Product vs. Process Tolerance
- Thread starter Dongzkie
- Start date
Hello there!
Have you calculated an uncertainty analysis for your process? I would start with that. Then, go four times that much.
It would also depend on the previous history of this balance, what range it is being used at, precision, etc.
As far as the acceptance tolerance, again, depending on the history of the balance, I would set the tolerance at the process tolerance. The only time the user should be notified of a failure is when it will affect their process.
When you say .08g, the balance can be .07 grams off and not affect anything? Or do you need to take 1/2 of the .08grams, and state that .05g might affect the process? Does that make sense? Let me know if it doesn't. I'm asking if the .08 is .08 heavy and/or .08 light; or .04 heavy and/or .04 light.
I was posting the same thoughts when you posted.
G
Geoff Withnell
Product tolerance and process tolerance - which are we discussing? Process tolerance is usually set as the portion of the product tolerance "budgeted" for this particular process, the maximum variability we can tolerate for this process. The measurement variability is an inherant part of the process variability.
Geoff Withnell
ex. process ==> conductor gram weight==> nominal:5.01g ; max:5.09g ; min:4.93g
GramScale readability is 0.01g ==> i want to know how to set a tolerance for the equipment with regards to the process.
GramScale readability is 0.01g ==> i want to know how to set a tolerance for the equipment with regards to the process.
Hello there!
Have you calculated an uncertainty analysis for your process? I would start with that. Then, go four times that much.
It would also depend on the previous history of this balance, what range it is being used at, precision, etc.
As far as the acceptance tolerance, again, depending on the history of the balance, I would set the tolerance at the process tolerance. The only time the user should be notified of a failure is when it will affect their process.
When you say .08g, the balance can be .07 grams off and not affect anything? Or do you need to take 1/2 of the .08grams, and state that .05g might affect the process? Does that make sense? Let me know if it doesn't. I'm asking if the .08 is .08 heavy and/or .08 light; or .04 heavy and/or .04 light.
Last edited:
I would suspect your uncertainty should not be a significant factor, but should still be calculated. I would set the tolerance for +/-.08 grams. I would adjust and such if there is any error observed. But only report if it exceeds process tolerance. However....
I have not seen anything about the balance capability. Not sure how it has been performing or what the mfg. tolerance is. You will be hard pressed to set a tolerance tighter than mfg. specification for it.
