Calibration Process QC Laboratory vs. Calibration of Shop Floor Tools

[AndyN]

I would like to make a couple of points.... before being dragged over the coals a bit more... :mg:

The instrumentation, etc in our lab where final inspection takes place will receive Calibration as they are now... This is where the data is generated.

Yes, I DO realize the potential for errors on arrival.... not ignorant of that.



Who said they ONLY use one standard... or don't know about Linearity?
These 'widgets' are NOT all one size... when these operators 'verify' their mics before performing the operation like described before, they may use a variety of calibrated standards... and may check their mics MANY times during the day...

So we send out the mics for calibration... gets its sticker and a defined re-calibration interval... I KNOW we can't just ignore any verification during the time frame between receipt and re-calibration... but that is what seems to me is being implied...




Then tell me how I can report the individual dimensions without a 100% inspection and over the years we did try shop floor data collection... and returned to a "lab" environment.

I do AGREE prevention is valid!!! no argument there...

I tell ya... Tough Crowd and some of the tones are a bit disturbing in regards to what you 'think' management style, etc is like here... I'm not here to defend anything but sure seem necessary.:truce:

Thanks for the attachment I will look it over.

We can only work with what you give us............if you tell me they use one measurement to validate their equipment, then that's all I have to go on........plus, that's what I've seen other people doing, without the knowledge.....There's important points missing from your descriptions and writing is a very one dimensional form of discussion..........

If it offended, it wasn't supposed to, we don't know you that well! We only really offend people who've been here a while!

 

[AndyN]

To help me understand better.....

Why can't the dimensions be recorded 'in-process' by the operators, instead of waiting for final? If necessary, it could be a (checked) transcription of those results, if presentation is important (the shop and op. handling aren't conducive to clean paperwork).

The final inspection can then be limited to a sample of key (let's suggest 'tight') dimensions, rather than everything having to be checked over (again)....

Just a thought.

 

[CarolX]

Suggested phrasing for the procedure that would satisfy an audit?

Hi thallecnc and Welcome to the Cove ,

How about adding this to your procedure?

"Only gages used for final product acceptance shall be covered by this procedure"

or

"Measuring devices used on shop floor shall not be subject to the calibration program. Only those gages used for final acceptance shall be part of the system"

There is NOTHING in the standard that says you must calibrate all of your gages. It is up to you to develope your system. Note to say that during an audit you may have some discussions on this.

I hope this helps to answer your question - the thread seemed to have gotten a bit off topic.

Again - welcome to the Cove.

 

[bobdoering]

How about adding this to your procedure?

"Only gages used for final product acceptance shall be covered by this procedure"

or

"Measuring devices used on shop floor shall not be subject to the calibration program. Only those gages used for final acceptance shall be part of the system"

There is NOTHING in the standard that says you must calibrate all of your gages. It is up to you to develop your system. Note to say that during an audit you may have some discussions on this.

I agree, the standard does not specify that you must calibrate all of your gages. And, it is up to you to develop your system. But, it has to meet 7.6, and it has to be an effective process.

If you believe - and can convince your auditor - that the gages on the shop floor are not used for "monitoring and measurement", especially if you have identified them in your "monitoring and measurement" requirement documentation on the shop floor (control plans in automotive terms), then good for you.

Also, will you be able to show that it is not "necessary to ensure valid results" on the shop floor? Because, if it is, measuring equipment shall be calibrated or verified at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards. Also, records of the results of calibration and verification shall be maintained. Do they record these verifications on the shop floor? If not, I would say they do not count.

Anyway, these are the vagaries you get to discuss with your auditor, as CarolX implied. I would not accept them, but in spite of it all, different auditors will look at things differently...some are more easily "convinced".

Here is an easy question: Have you ever had any parts fail final inspection? No? Then you may be able to convince your auditor that you are properly monitoring and controlling, and your system must be effective. If not...then you have some dancing to do....

 

[Jen Kirley]

Lots of confusion about calibration. To clarify, in my book varifying a tool measures accurately when checked against a NIST traceable standard is calibration. IMO, verification is just another term for it.

I would support inspecting and calibrating every tool being used to verify product goodness. I used to do this for >350 of them. It takes some time, but it's much more cost effective than sending out the tools or ending up with an error in production. I used to do cleaning and simple repairs of my shop's dial calipers too, because it didn't take more than a couple trips to the repair shop to exceed their replacement value...not to mention the ocst and hassle of having all those spares while you send XYZ away for ___ days. The gage blocks would be certified yearly, and a master set (kept in the Lab) could be set for 3 up to year cycles. That was based on usage.

I would use that time to also inspect the calipers' jaws for damage after being dropped; check for spring, clean out the tracks and make sure the tails were tight. Along with checking accuracy, micrometers would need to have their barrels and spindles checked for flatness. This doesn't take very long, and helps ensure the tools are in satisfactory condition overall. Without a program like this, it's mighty hard to offer a sound assurance of tool control to a customer.

IMO, it's a good idea to have the operator take measurements during production, and jot them down on the shop traveler or some other kind of record. How valuable this is depends on the expense of finding out the thing is no good after subsequent steps are performed. A roving inspector can do first piece, then take a sample now and again, and sign for it somehow. In this way both the operator and inspector have responsibilities, and the needed controls can be achieved in a timely way.

thallecnc, please forgive us if we seem abrupt but do not forgive us if we are rude. We often get spirited dialogs going here, but we shouldn't make you feel bad in the process. You are welcome here!

I hope this helps.

 

[bobdoering]

Along with checking accuracy, micrometers would need to have their barrels and spindles checked for flatness. This doesn't take very long, and helps ensure the tools are in satisfactory condition overall.

This is so true, and a lot of people miss this step. They check the bias and linearity with a handful of blocks and toss them back. With grinding especially, it is very easy to wear ruts unto the faces of the micrometer anvils - and it happens even faster if the parts are not meticulously cleaned from the grinding coolant. It also tears up air gages. This has been shown to be an easy way to scrap parts, while thinking you are doing OK. For micrometers, some folks use a gage ball and verify it all over the surface of the anvil, others use optical flats and a monochromatic light.

If I had not witnessed this problem myself, I would have probably thought it was overkill. It is not.

 

[TamTom]

Wow,

I just read the whole thread and now I'm confused, I'm just looking for a cost effective system to "calibrate" (not according the differend standards) or verify all our measurement instruments (talking about > 500) from 4,5 mm up to 500 mm (all kind of gauges).

My idea was to have outside calibrated tools in the inspection and outside calibrated measurement standards and set-up gauges, and to verify the tools in production by a regulary set-up with the set-up gauges and a yearly "calibration" against the gauge from inspection.

With the very large mircometer gauges, I only can use the setup gauges, cause a outside calibration would take 3 days at a minimum, and we have only one (used not so often but too often to send outside [this has something to do with our production planning -> a total mess])

And here is my point of confusion, is this ok or not? Or do you think a good calibration system would send out all gauges?
This is not about the standard or costs.

Greetings

TamTom

P.S. We also have a final inspection, and we need it, cause of the requirements of the Power generation industry, that some inspection could only be done by certified and independend personel.

 

[BradM]

Wow,

I just read the whole thread and now I'm confused, I'm just looking for a cost effective system to "calibrate" (not according the differend standards) or verify all our measurement instruments (talking about > 500) from 4,5 mm up to 500 mm (all kind of gauges).

My idea was to have outside calibrated tools in the inspection and outside calibrated measurement standards and set-up gauges, and to verify the tools in production by a regulary set-up with the set-up gauges and a yearly "calibration" against the gauge from inspection.

With the very large mircometer gauges, I only can use the setup gauges, cause a outside calibration would take 3 days at a minimum, and we have only one (used not so often but too often to send outside [this has something to do with our production planning -> a total mess])

And here is my point of confusion, is this ok or not? Or do you think a good calibration system would send out all gauges?
This is not about the standard or costs.

Greetings

TamTom

P.S. We also have a final inspection, and we need it, cause of the requirements of the Power generation industry, that some inspection could only be done by certified and independend personel.

Hello TamTom! Essentially, you should be able to set up whatever verification system works for your organization. Just assure that your standards are traceable to N.I.S.T. or its equivalent. Too, you will want to assure that appropriate uncertainty ratios are used.

Say you have the reference (sent off for calibration), secondary (calibrated using the reference standards) and the working instruments (calibrated usine the secondary standards). They should all adhere to adequate ratios. You should have good procedures in place for doing the checks.

Did that answer your question?