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Nonadjustable M&TE - 10 year calibration interval? Pin Gages

D

danielp1

#1
This is a memo I received from our QM on calibrating pin gages...
Any thoughts??

Nonadjustable M&TE is inherently stable and includes balance weights, current shunts, thermometers, tape measures, rulers, gage blocks, pin gages, thermocouples and thermocouple extension wire; and devices, units, components and items that cannot be adjusted or do not significantly change after use. The calibration interval for inherently stable M&TE that is used for acceptance is 10 years.
 

Jim Wynne

Staff member
Admin
#2
Re: 10 year calibration interval??

This is a memo I received from our QM on calibrating pin gages...
Any thoughts??

Nonadjustable M&TE is inherently stable and includes balance weights, current shunts, thermometers, tape measures, rulers, gage blocks, pin gages, thermocouples and thermocouple extension wire; and devices, units, components and items that cannot be adjusted or do not significantly change after use. The calibration interval for inherently stable M&TE that is used for acceptance is 10 years.
Welcome to the Cove. :D

I would ask the QM how he settled on 10 years. Why not 50? What does he expect might happen in 10 years that won't happen in 5? How does he know this? If he believes that there are things that "do not significantly change after use," why do they need to be calibrated at all?
 
D

danielp1

#3
Re: 10 year calibration interval??

Actually, here is the much more of the document he sent.....(I think this is an appendix to a procedure; I'm sure I have seen this somewere before).

The Operator is only required to check inherently stable M&TE for damage
prior to each use because nonadjustable M&TE does not go out of tolerance
under normal use.
For instance, retractable tape measures and rulers are sometimes used for
measuring quality characteristics. For a retractable tape measure, the
Operator must check to confirm that the numbers and measurement increments
are not worn off and check the metal tip to confirm that it is firmly
affixed and not worn off. Prior to each use of a ruler, the Operator must
check the starting edge of the ruler to confirm that it is sharp and
completely free of wear and confirm that the numbers and measurement
increments are not worn off. Whenever a tape measure or ruler is no longer
in good shape it should be discarded and replaced.
To control the inventory of inherently stable M&TE, determine what brands
of inherently stable measurement devices are in use. If there are several
different brands in use, decide on up to three reputable brands. Throw out
all the other brands and replace with the three approved brands. Copy the
manufacturer or distributor catalog page that reports the accuracy or
tolerance of the device, or call the manufacturer of each brand and
request a certificate, such as a Certificate of Manufacturing Tolerance or
Certificate of Calibration. This is a statement from the catalog or
certificate from the manufacturer that states the tolerance used to
manufacture the devices (smaller is better.) Keep this catalog page or
certificate on file with other calibration records.
If the tolerance given
by the manufacturer exceeds (is tighter than) the measurements taken by
Operators then the entire brand of measurement device is considered
validated for use.
For instance, if Operators only measure to +/- 1/16" with a retractable
tape measure and the tape measure is certified as manufactured to +/-
1/32", then the brand of tape measure is approved for use.
Operators are required to ONLY use inherently stable measurement devices
from the accepted brands with certificates on file. (Hang signs that list
"approved brands")
With this method, as long as the approved brand is listed and a catalog
page or manufacturer's certificate is on file, there is no need to
periodically calibrate inherently stable measurement devices. There is
also no need to put calibration tags or stickers on them because the brand
name acts as the means to trace the device back to the manufacturer's
certificate on file.
 

howste

Thaumaturge
Super Moderator
#4
Calibration frequency needs to be established based on risk. How frequently are they used? What kind of materials are they used to check? If the calibration shows out-of-tolerance, how much material do you want to recall?
 

bobdoering

Stop X-bar/R Madness!!
Trusted
#5
Re: 10 year calibration interval??

Actually, here is the much more of the document he sent.....(I think this is an appendix to a procedure; I'm sure I have seen this somewhere before).

The Operator is only required to check inherently stable M&TE for damage
prior to each use because nonadjustable M&TE does not go out of tolerance
under normal use.
What are you measuring, marshmallows? You need to verify with data that
nonadjustable M&TE never wears, never breaks - especially for 10 years. 20 years of data should help support that....:rolleyes:


For instance, retractable tape measures and rulers are sometimes used for measuring quality characteristics. For a retractable tape measure, the Operator must check to confirm that the numbers and measurement increments are not worn off and check the metal tip to confirm that it is firmly
affixed and not worn off. Prior to each use of a ruler, the Operator must
check the starting edge of the ruler to confirm that it is sharp and
completely free of wear and confirm that the numbers and measurement
increments are not worn off. Whenever a tape measure or ruler is no longer
in good shape it should be discarded and replaced.
So, pretty much operators are doing the calibrations (except checking to a standard - I am surprised that wasn't tossed in for 'good measure') - just not documenting them.

There is
also no need to put calibration tags or stickers on them because the brand
name acts as the means to trace the device back to the manufacturer's
certificate on file.
I suppose that will work if there is only one of each device.
 
#6
Who wrote that? They clearly have no concept of the use and consequences of the subject equipment! In a previous life, my company had a huge problem where a screw plug gauge - very def. not 'adjustable' - was badly worn through its repeated use in less than 12 months.....the rejects and other issues that gauge caused led to a major revision of our calibration system and we calibrated everything on a (very conventional) 12 month basis.

No, without data, no-one should be recommending such a large period......
 

BradM

Staff member
Admin
#8
Who wrote that? They clearly have no concept of the use and consequences of the subject equipment! In a previous life, my company had a huge problem where a screw plug gauge - very def. not 'adjustable' - was badly worn through its repeated use in less than 12 months.....the rejects and other issues that gauge caused led to a major revision of our calibration system and we calibrated everything on a (very conventional) 12 month basis.

No, without data, no-one should be recommending such a large period......
My thoughts exactly.... Big sirens were going off in my head when I read this. Yes... that's beside the usual voices and noises in my head.:lmao:

I'm going to borrow Jim's post a bit and state that why bother calibrating at all, if you are sure nothing ever changes?

1. You need data to back up the assertion. Saying, if you have been calibrating it and have evidence there is no problems, that's one thing. But it sure seems risky to just summarily make such estimations. The data will show stability in the device, and thus would require less verifications.

2. It would amaze you at the different things that can occur. Pins get worn spots on them, thermocouples drift, temperature controllers that have been "programmed" by operators :lmao:, etc. If you are not periodically checking your equipment, you are not going to pick these things up.

Just because something is not adjustable does not mean its accuracy cannot deviate.
 

bobdoering

Stop X-bar/R Madness!!
Trusted
#9
2. It would amaze you at the different things that can occur. Pins get worn spots on them, thermocouples drift, temperature controllers that have been "programmed" by operators :lmao:, etc. If you are not periodically checking your equipment, you are not going to pick these things up.
That is exactly correct. One of the points I emphasize in my metrology classes is when you measure something (with a contact gage), you change both the item you are gaging and the gage itself. Even if it is a molecule at at a time...it happens. How much? It depends (of course.) But, it is up to you to prove how much - a part of the point of calibration.
 
5

56flh

#10
I'm kind of in the same situation as indicated in the above posts.

We have a well established ISO 9001 QMS at the machining location of our company with all gages and measuring equipment calibrated and entered into a software package that does a good job of tracking calibration intervals etc. of the 3000+ items that are calibrated (including gage pins annually). Gage pins and gages are calibrated utilizing a Pratt and Whitney super mic and visual examination.

I am trying to establish requirements for calibration in our fabrication location where tolerances are more in the +/- 1/16 range compared to the precision required in the machining environment. We serial numbered and entered all tape measures into our software and established review frequency for these devices since they are subject to wear from use. I am questioning what to do about squares, protractors, radius gages, etc that that are not as prone to wear. I have been considering establishing a review frequency to check for dings, imperfections or damage that could effect function of the device and labeling as "QA Approved" and tracking with the calibration software.

Does this sound like a workable solution?
 
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