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

L

Lexylou

#1
I am still fairly new to the Cove and find this web-site so helpful and if I'm not in the correct thread please tell me.
My question is " Do I need to calibrate all gages or only those that I am using to final inspect the product?"

I just left a ISO team meeting on this very subject.

During one customer audit the auditor told us that we need to only calibrate those gages needed for final inspection of our final product. We than had a different customer audit where that auditor tells us that every gage in the shop (which includes all employee owned gages) need calibrated. This is a tool shop where there are 30 men that all have their own inspection gages along with the company owned inspection gages. I'm looking at hundreds of gages. We are looking at AS9100 certification.
Please help......It has become someone's full time job just to do calibrations.

:mg:
 
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T

trainerbob

#2
Re: Control of Measuring and Monitoring Instruments

If you can't verify that a gauge or caliper(regardless of who owns it) is accurate how can you verify the meterial going to the customer(either internal or external) is correct? Are they measuring to a spec or a print? If I was getting a part from someone else to do some work on it I would want to know that the part I am getting is correct. Without calibrated gauges it is awfully easy to compound errors or problems. There are enough problems when everything is "right".
 

howste

Thaumaturge
Super Moderator
#3
"Do I need to calibrate all gages or only those that I am using to final inspect the product?"
Here's the requirement in AS9100:
AS9100 Rev B clause 7.6 said:
Where necessary to ensure valid results, measuring equipment shall a) be calibrated or verified...
Your organization has to determine what equipment is "necessary to ensure valid results." If there are final inspection checks that would detect a problem upstream, then you could argue that the upstream gaging doesn't require calibration.

Having said that, there are risks to not having all measuring equipment calibrated. If an uncalibrated gage goes out of tolerance, there's the cost of sorting, reworking, or scrapping product that may have been produced prior to the final inspection. If uncalibrated gages are available in the facility, someone may find and use the uncalibrated equipment at final inspection.

My preference is to have all equipment calibrated. If it's worth measuring, it should be done with equipment I know I can trust.
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#4
My preference is to have all equipment calibrated. If it's worth measuring, it should be done with equipment I know I can trust.
:agree1:That is the bottom line. The converse is if you don't care enough about the measurement to calibrate the gage, why measure at all? If you ever have bad parts, you would have just blamed the gage for being out of calibration anyway.
 
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BradM

Staff member
Admin
#5
If the value matters, have it calibrated (or verified to some extent). :D

I would assume that at some point, people have the instruments to give them readings. They use those readings for something. What if that instrument is off .0001; .001. .01. 10? At some point, that error will matter.

So, you can either segregate those instruments which are calibrated/ non-calibrated (not my recommendation:D) or, calibrate them all.

Now... I would give you a thought to ponder. I bet you could get rid of 1/2 the instruments that you have, and it probably would not affect operation.:D

Just saying, determine what you need; sell the rest or have them take them home; or whatever. Then, calibrate the rest.

If these are micrometers/calipers, I bet you could buy a couple of set of gauge blocks, and set up an internal verification system. People could check them once a week; prior to use; before/after; every other week; whatever suits your organization's purpose. Just document it somehow;).

Also, teach and motivate the staff as to the value of calibrated instruments. This should involve discouraging them from keeping "contraband instruments" that they have hidden and not calibrated.:DThose instruments are so dangerous. They can produce errors and failures; of which the true root cause would be extremely difficult to identify.
 

BradM

Staff member
Admin
#6
:agree1:That is the bottom line. The converse is if you don't care enough about the measurement to calibrate the gage, why measure at all? If you ever have bad parts, you would have just blamed the gage for being out of calibration anyway.
:applause::agree1:

Akio on the ASQ board really made me think about this one. A lot. If it matters, calibrate it. If it doesn't matter, why have it?

While I still think you need "for reference only" he really challenged me on that. His point is why have it? What does it do for you??
Well, we use it in case....
:), his argument: it matters; check it somehow. If you say "we don't need it". Then, get rid of it; it's taking up space.:tg:
 

bobdoering

Stop X-bar/R Madness!!
Trusted Information Resource
#7
Those instruments are so dangerous. They can produce errors and failures; of which the true root cause would be extremely difficult to identify.
..and the MOST embarrassing to explain to a customer when it is identified. You can end up paying for sorting costs, repair costs, replacement costs...all kinds of misery because of that ridiculous stuff. It must not be tolerated.
 

Big Jim

Super Moderator
#8
Here's the requirement in AS9100:

Your organization has to determine what equipment is "necessary to ensure valid results." If there are final inspection checks that would detect a problem upstream, then you could argue that the upstream gaging doesn't require calibration.

Having said that, there are risks to not having all measuring equipment calibrated. If an uncalibrated gage goes out of tolerance, there's the cost of sorting, reworking, or scrapping product that may have been produced prior to the final inspection. If uncalibrated gages are available in the facility, someone may find and use the uncalibrated equipment at final inspection.

My preference is to have all equipment calibrated. If it's worth measuring, it should be done with equipment I know I can trust.
Howste said it more eloquently than I would have.

To me, the real point is, why take the risk?

And risk is going to have more scrutiny with AS9100C when it is finally released for use.
 

Sidney Vianna

Post Responsibly
Staff member
Admin
#9
And risk is going to have more scrutiny with AS9100C when it is finally released for use.
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.
 
B

brahmaiah

#10
I am still fairly new to the Cove and find this web-site so helpful and if I'm not in the correct thread please tell me.
My question is " Do I need to calibrate all gages or only those that I am using to final inspect the product?"

I just left a ISO team meeting on this very subject.

During one customer audit the auditor told us that we need to only calibrate those gages needed for final inspection of our final product. We than had a different customer audit where that auditor tells us that every gage in the shop (which includes all employee owned gages) need calibrated. This is a tool shop where there are 30 men that all have their own inspection gages along with the company owned inspection gages. I'm looking at hundreds of gages. We are looking at AS9100 certification.
Please help......It has become someone's full time job just to do calibrations.

:mg:
All measuring equipment you have mentioned in your control plan should be calibratedand and all instumentation on the machines and those used by maintenance dept. should also be calibrated because they directly affect product quality.If you have dozens of pressure gauges and temperature gauges on the machines you wiil face real problem.There you have to calibrate only critical gauges and provide justification.
V.J.Brahmaiah
 
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