How often for micrometer calibration?

[Sean Kelley]

I am looking for some guidance on how often micrometers should be calibrated. We do our own internal calibrations. We have recently added a new production facility (making stainless rod) and have new types of micrometers. We need to determine how often to do this. I was told our old system was based on manufacturer recommendations (1 month).

 

[Mike S.]

We've used every kind from cheapo Chineese mics to B&S and Mitutoyos. All of them have been fine at 3 month cal intervals in very heavy use (3 shifts), 6 months in moderate-to-heavy use. The only caveat is that this assumes the operator (thru training) is keeping them relatively clean and gunk-free and regularly zero's them out (at least a few times daily) to verify things are working as expected and the faces did not get gunk on them.

 

[Jimmy Olson]

I would agree that 3 or 6 months would be fine. Every month seems a bit excessive. You may want to start them out at every 3 months and see how they do. If you notice that they are constantly having problems then you may want to change it to monthly. On the other hand if you notice that they are staying in good condition then you can bump the cycle out to 6 months.

It basically comes down to whatever you feel comfortable with.

 

[CarolX]

Sean,

We use to do ours monthly....in fact, everything was done monthly. Last year I sat down with the records and reviewed the data....and guess what....we were in massive overkill!!! I increased our frequency to 3 months. In about 6 months I will look at it again and probably increase some to 6 months.

I recomend you review your past history and adjust frequencies if warranted.

CarolX

 

[Claes Gefvenberg]

I recomend you review your past history and adjust frequencies if warranted.

CarolX

Aye, there's the rub. It all depends on how they are used, so this is absolutley correct.
If you have no past history you just start off with a massive safety margin and then crank it down when you know that you can safely do so.

/Claes

 

[Grizz1345]

I have been handling calibrations here for 5 years. I use a one year cycle for most tools. Very few tools have fallen out of cal in this time span. I do calibrate thread gages on a 6 month cycle. Some areas I have the cycle down to 3 months for thread gages. I am regularly auditted and have had no problems yet. I was not aware that the manufacturer's cycle time was one month. This seems a little bit of overkill.

 

[Atul Khandekar]

Old question

Here is an old question for which I haven't yet got a satisfactory answer:

Is it possible/acceptable to use the Stability Test control charts in MSA to determine when a gage should be sent for calibration? Condition-based calibration instead of time-based.

Thanks.

 

[Charles Wathen]

What I do at my facility is to review all our out of tolerance instruments and use the Interval Calculator to determine if I need to reduce the cycle time. I also then use Interval Calculator to determine if any instruments I can increase in cycle time. You would be surprised at how many instruments you calibrate during a year that are never found out of tolerance.

All our Mitutoyo Digimatic Micrometers are at the 14 month interval currently. We started with intervals of 6 to 9 months and have gradually increased it over the years. For example, in June when I reviews our instruments, we performed 97 calibrations on these Mitutoyo Digimatic Micrometers and did not find a single one out of tolerance. Our interval in June 2003 was 12 months, but we have increased it to 14 months.

For those intrested, here is were you can download the free Interval Calculator:
http://www.isgmax.com/freeware_l.htm

 

[Claes Gefvenberg]

That makes good sense Charles.

I'l check that link out at work tomorrow. Thank's

/Claes

 

[energy]

I little detour?

I am looking for some guidance on how often micrometers should be calibrated. We do our own internal calibrations. We have recently added a new production facility (making stainless rod) and have new types of micrometers. We need to determine how often to do this. I was told our old system was based on manufacturer recommendations (1 month).

While this thread deals with frequency for calibrating Micrometers, I'm curious about an old method used to check the flats on the Mic. In addition to using Jo-Blocks, we had to use calibrated pin gauges in three positions across the flats. To check for wear. Still done that way?