Do all gages need calibration or only those used for final inspection?

Big Jim

Super Moderator
#11
Let's not confuse certification and usage. 9100C has been released several months ago. Nobody can attain accredited certification against it, but organizations could certainly be working towards conformity against it, right now.
Perhaps I should have said "available for registration".
 
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A

anil123

#12
Actually, first understand why inspection is required, if it is so important that variation in will affect next subequent operation then it is required. Now if measurement system used is not giving correct value then next operation will be affected, hence calibration is required for those equipements where inspection is considered as important
 
M

M Komarmy - 2012

#13
Another side to this discussion is the higher level quality philosophy you want to run your business by. By inspecting and sorting the final output or dependent variables of your process, you are incurring unnecessary costs. It has also been said that 100% inspection is not 100% effective. It is possible that by running to this philosophy you will have high internal scrap costs and also still allow unacceptable parts to get to your customer.

By checking the independent process variables throughout the process and controlling them, your end result will be improved. To do this, each process step must have a control plan and you need to measure and control features important to each downstream customer. This requires capable measurement equipment. Calibration to verify accuracy as well as R&R, linearity, and stability should be done on measuring equipment.

This is fundamentally explained by "six sigma" with the y=f(x) relationship, where the output (y) is a function of independant variables (x).
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#14
This is fundamentally explained by "six sigma" with the y=f(x) relationship, where the output (y) is a function of independent variables (x).
Another equation I like to consider is the one attached, total variation. When people measure an item, and expect it to represent the process, the forget that the result they get is not the measure of the process variation, but of the total variation. It includes the additive effects of all errors. So, if you have no idea what those other errors are, you really have no idea if the data you have comes anywhere near reflecting the process. I am not sure how that "shortcut" in analysis would make anyone comfortable with results of uncalibrated gages, as well as the other errors involved.
 

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Jim Wynne

Staff member
Admin
#15
Another side to this discussion is the higher level quality philosophy you want to run your business by. By inspecting and sorting the final output or dependent variables of your process, you are incurring unnecessary costs. It has also been said that 100% inspection is not 100% effective. It is possible that by running to this philosophy you will have high internal scrap costs and also still allow unacceptable parts to get to your customer.

By checking the independent process variables throughout the process and controlling them, your end result will be improved. To do this, each process step must have a control plan and you need to measure and control features important to each downstream customer. This requires capable measurement equipment. Calibration to verify accuracy as well as R&R, linearity, and stability should be done on measuring equipment.

This is fundamentally explained by "six sigma" with the y=f(x) relationship, where the output (y) is a function of independant variables (x).
While all of this is basically true, it was "fundamentally explained" long before Six Sigma was an evil gleam Motorola's corporate eye.
 
T

trainerbob

#16
Lexylou,

By now you should have a pretty good consensus - If a gauge is worth using, it should be calibrated. Normally, after initial calibration it does not a require a person full time to maintain the calibration. Put them on a schedule that makes sense for each individual gauge based on knowledge, past history, and manufacturer's recommendation. Your parts will be better, your quality will be better, your quality philosophy will be more evident, and your customers(both internal and external and internal) will be happier.
 
M

M Komarmy - 2012

#17
While all of this is basically true, it was "fundamentally explained" long before Six Sigma was an evil gleam Motorola's corporate eye.
I agree! I remember attending a 4 day seminar with Dr. Deming in 1984 and he understood this better than anyone. Although I attended black belt training, I do not agree with the generic 1.5 sigma shift concept that Mikel Harry uses to explain process shifts and drifts. However, the y=f(x) is a good simple way to explain the idea of the customer/suppplier relationship throughout the value chain, especially to managers who have consumed the six sigma kool aid.
 
#18
We must also separate calibration from verification. In many cases, verification may be that is all requried. But, what others have stated about why have it if it doesn't matter.

:topic: I put "for reference only" on documents in the same category as for gages. If it ain't necessary, dump it! :mad:
 
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