First Draft Micrometer Calibration Procedure

[wesatwork]

You could save yourself some time by just using military specification for micrometers. The calibration environment should be:

Relative Humidity: Preferably under 50% to minimize corrosion. Re. MIL-STD-120, Para. 8.2.2
Temperature: 68 F (20 C). Re. ASME/ANSI Y15.5m, Sec. 1.4, Fundamental Rules (K) and MIL-STD-120, Para. 8.2

I wanted all of the calibration procedures in our department to look and feel the same. If I copy different specs. from different sources for all of the different devices then they would not read the same. We have quite a few procedures to write for very custom applications that you can't get a canned procedure. Does that make sense to everyone else?

 

[Hershal]

A couple of thoughts, realizing this is internal cal.

Your source (e.g., NA17-20 series or ASTM procedure) should be referenced. And to be traceable calibration, the measurement uncertainty must be calibrated. Also, need to record the specific traceability of the standards used. Otherwise this is actually verification, not calibration.

 

[wesatwork]

A couple of thoughts, realizing this is internal cal.

Your source (e.g., NA17-20 series or ASTM procedure) should be referenced. And to be traceable calibration, the measurement uncertainty must be calibrated. Also, need to record the specific traceability of the standards used. Otherwise this is actually verification, not calibration.

Thanks for the feedback-
Does ISO 9001 require procedures to be referenced to an external procedure? You can't create a procedure to suit the use?

We are just starting to work on calculatating Measurment Uncertainty. Each calibration we perform gets a calibration report, eventually our calibration reports will be calculating MU for each report created, but we just aren't there yet. I don't know how else to move forward other than not referencing MU for now.???

Our calibration reports have dedicated cells just for recording all M&TE used, via a Internal ID# Example CS12345- is calibration standard we'll say gage blocks. On our server you can pull up the calibratoin reports for all of our calibrated devices by the Internal ID#. That will work for traceability right?

 

[Mikishots]

I may have missed something, but this procedure seems to be quite broad in its scope; are you planning on writing a procedure for every type of M&TE, or one high level calibration procedure and then a work instruction for each type of M&TE?

An observation; what do you do if the device is dropped while in use?


What about if the user finds that it's not measuring correctly? How do you deal with a failed "found as" (validity of previous measurements) during your scheduled cal?

As you've stated that you're at the beginning of creating a new system, it might be worth considering to draft a calibration procedure, and a work instruction to address each device type. It will definitely cut down on the redundancy that would be inherent to your currently planned method.

You've also mentioned in Sec. 5.0 that there are unique safety measures - what are they?[/QUOTE]


1. This procedure is for outside micrometers only.

2. Any calibrated decice that is dropped is always recalibrated prior use. It is not a documeted practice, but it is well engrained into our department.

3.see Section 8.2

4.I have a universal draft and this is a specific (outside micrometers) device cal. procedure.

5.There are no unique safety measures for this proceudre, but some procedures will have helpfull information. Examples may be exposure to voltage potential; hydraulic pinch points; etc.

8.2 doesn't address the disposition of parts that were measured with the out-of-cal device, only the micrometer itself. The standard asks that you also take appropriate action on any product affected as well.

It's fine if you want to have a separate procedure for outside micrometers only, but you're setting precedence. An individual procedure for each device (which will include repeating redundant info if you want to preserve the "look and feel" from procedure to procedure) is going to very time consuming and unnecessary work, especially for someone who seems to be pinched for documentation time.

At our work place, we have ONE procedure for calibration but we have many WI's, one for each type of device. If, for whatever reason, you need to make a change to the upper (general) areas of the procedure that are common to each, you're looking at having to revise each and every one of them to ensure consistency.

On another note, you can depend on engrained behavior, but in my experience, documenting it just once can save you future headaches. The prcedure doesn't specifically say that cal is required after a drop, so if it isn't carried out, the fault only lies with the procedure.

 

[AndyN]

May want to consider adding a repeatability check using a gage ball to ensure that the anvils on the micrometer are not worn.

Can you help me with this one? I've not heard how this is carried out. I've heard of using optical flats, but never a gauge ball. I'm willing to learn another method! Thanks!

 

[AndyN]

I wanted all of the calibration procedures in our department to look and feel the same. If I copy different specs. from different sources for all of the different devices then they would not read the same. We have quite a few procedures to write for very custom applications that you can't get a canned procedure. Does that make sense to everyone else?

I'm not sure it makes much sense to me. Is that really your best objective for documentation? So they look the same? Isn't it better to get the best possible result for the smallest amount of work to create the instruction? Surely, if someone has done this before - and it has been done many, many times - why not just use the industry standard. It is, after all, what they're there for...

 

[wesatwork]

8.2 doesn't address the disposition of parts that were measured with the out-of-cal device, only the micrometer itself. The standard asks that you also take appropriate action on any product affected as well.

It's fine if you want to have a separate procedure for outside micrometers only, but you're setting precedence. An individual procedure for each device (which will include repeating redundant info if you want to preserve the "look and feel" from procedure to procedure) is going to very time consuming and unnecessary work, especially for someone who seems to be pinched for documentation time.

At our work place, we have ONE procedure for calibration but we have many WI's, one for each type of device. If, for whatever reason, you need to make a change to the upper (general) areas of the procedure that are common to each, you're looking at having to revise each and every one of them to ensure consistency.

On another note, you can depend on engrained behavior, but in my experience, documenting it just once can save you future headaches. The prcedure doesn't specifically say that cal is required after a drop, so if it isn't carried out, the fault only lies with the procedure.

In order to meet a deadline I am submitting some procedures in this current format. I do see value in what you are saying, in regards to having a higher level calibration document and numerous/individual calibration process steps. Moving forward I may write some more device procedures in the same format and begin a draft (I am green and still working out the big picture ideas) for the higher level calibration document.

 

[wesatwork]

Can you help me with this one? I've not heard how this is carried out. I've heard of using optical flats, but never a gauge ball. I'm willing to learn another method! Thanks!

I have never done it myself, but I think you measure your gage ball standard at several places between the anvil faces. Four corner points and center?

 

[AndyN]

I have never done it myself, but I think you measure your gage ball standard at several places between the anvil faces. Four corner points and center?

Hmmm...I'd go with the tried and trusted method using an optical flat!

 

[Mikishots]

Upon review of the thread, I've been thinking that some of the confusion lies with the definition of a procedure and a work instruction. A procedure defines what needs to be done at what time and under what conditions. A work instruction defines how to do something.

So according to these definitions, one procedure can be drafted that describes the calibration process - controls, identification, schedule, recall method, reference standards, lab conditions etc. The multiple work instructions would be specific to a type of equipment; one for slide calipers, one for pressure gauges, one for micrometers, one for pin gauges etc.

Hope that helps.