Verbage to cover tape measures

J

JRKH

I know I know. It seems we beat this one to death, but I am trying to put together acceptable verbage to clear a NC from our last audit. We use tape measures for measuring to +/-.06 and up to 8 feet or more. Since most items are checked multiple times during the production cycle using different tapes I do not see a need for a heavy duty recall system for our tapes. The verbage I have come up with is listed below.

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Tape measures used by production personnel are verified during production by one or more of the following methods.
1) Checking the same measurement with another tape measure.
2) Checking the same measurement with another, more precise instrument.
3) Verified by checks at subsequent manufacturing operations.
4) Checked against a steel rule
Tape measures used by Quality Control personnel are verified at least monthly against a steel rule maintained for this purpose .
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What does the group think, will this fly?


Also for the probability crowd a question:

What is the probability that two metal tape measures used to check the same measurement will have the same error in the same direction? In other words what is the confidence level here?

If my process calls out that a part be checked by two persons and two different tapes, can I claim a reasonable degree of confidence that the measurement is correct?

Happy Friday :eek:
 
S

SteelWoman

We also use tapes a lot here. We verify them at the beginning of each 12 hour shift against a "standard block," and the tapes can be "re-calibrated" every 6 months with a more thorough calibration against a variety of standard blocks. I say "can" because in 6 years I've never seen a tape here actually LAST long enough to get completely re-calibrated. Verifying them every shift limits your recall potential if there's a problem found.

I can also say that in 6 years I've only ever seen ONE defective tape - it was missing an inch between 6 and 7? ! Bizzarro.

We recently solicited the manufacturer that MAKES the tapes for a letter attesting to the standards they use for manufacturing tapes - it turned out, to my surprise, to be quite stringent. We keep the letter on file "just in case" it comes up during an audit.

Course, you could ask my assistant and he'd tell you I keep EVERY PIECE OF PAPER on file "just in case." It's not a problem for ME - HE has to do the filing! :vfunny: :vfunny:
 
S

SteelMan

SteelWoman said:
Course, you could ask my assistant and he'd tell you I keep EVERY PIECE OF PAPER on file "just in case." It's not a problem for ME - HE has to do the filing! :vfunny: :vfunny:

I often wonder if I have copies of the same thing just to be certain!
 

Mike S.

Happy to be Alive
Trusted Information Resource
I think Steelwoman's idea of a letter from the tape mfr. is a great one. :agree:

I think a statistical confidence interval is impossible to calculate based on the available data presented, but the odds of 2 tapes failing the same way might be higher if the tapes were the same mfr. and type.

I have no real problem with your plan, JRKH, except for the part of measuring 1/16" with a tape makes me a little leery. I have several brand-name steel tapes where I think being off by 1/16" is very easy to do. What is the tolerance? For these tighter tolerance/small things I might lean toward a steel ruler or, better yet, calipers, but you know the process better than I. JMO.
 
JRKH said:
I know I know. It seems we beat this one to death, but I am trying to put together acceptable verbage to clear a NC from our last audit. We use tape measures for measuring to +/-.06 and up to 8 feet or more. Since most items are checked multiple times during the production cycle using different tapes I do not see a need for a heavy duty recall system for our tapes. The verbage I have come up with is listed below.
I can't believe that +/- 1/16" is a reasonable/required/necessary tolerance on an 8' piece. Is it really? I know it wouldn't matter in our wire looms or harnesses. If you are measuring a steel rod that must fit this tolerance for the next assembly up, I would be investigating hard go-no go fixtures.

Do you have a scrap and rework problem with this kind of piece? If not, I would stick with what you are doing and use the 4 point solution you suggested.
 
G

Grizz1345

I have our tape measures on a 1 year calibration cycle. The tolerance is 1/32. I too find it seldom that a tape measure lasts more than one cycle. I use a 5' vernier caliper to do the calibrations. I agree this might be overkill but it is what was available when I started to do calibrations here.

Have a great day. :lick:
 
K

Ken B.

Our Quality Manual reads as follows,
Due to the type of operations and requirements for the accuracy of measurements, tape measures used in the facility are not required to be calibrated. operator can use any tape measures, however ensure that these tape measures are verified against the Calibrated Master Steel Rule available in the production office periodically or when ever they found visible errors or damage.

We have never had problems with this during audit. Good Luck.
 
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