We have numerous Test Gauges, Digital Calibrators, Multimeters, Thread Gages, Step Gages, etc. within our facility. Test Gauges are used on a daily basis and have a calibration date of every three months. Other gages, such as thread gages, are rarely used and have no calibration date. We only use the thread gages, step gages, and certain other measuring devices, when a pallet of parts come in to check a very small sample.

As far as I'm concerned, these particular gages have never been recalibrated/reverified since their acquisition when they were brand new years ago. They are not electrical devices and are handled and stored properly. The only label(s) on each gage range from the manufacturer, manufacturer number, size of thread, etc. There is no mention of calibration status, calibration intervals and date of next calibration.

Since these gages are rarely used, are non-electrical, and handled/stored properly, what could an external auditor do about them? Having them all recalibrated now will cost thousands of dollars. It's not cost effective just to have the auditor pleased.

Any suggestions?

As long as you have the history you can extend the intervals based on observed stability.
The other approach you might concider is a calibration cycle based on use for those tools only used once every now and then.
Your approach taken would have to be documented and the calibration actuals on file to suport your practice.
You will always deal with the auditors view that the risk is greater with the longer intervals but if you have the data to suport your practice you should be fine.

Search the terms calibration frequancy, calibration use, ect and you will find plenty of info to concider.
:2cents:

If you very rarely use them, you can pull them out of service, and calibrate them when you need them. You may opt to calibrate on a number of checks frequency rather than a time frequency (tracking possible wear) - but you need a valid system to track it. You can even have an extended period, such as 2 or 3 years, as long as you can sensible justify it. It all boils down to the audit question: How do you know the gage is still reading correctly? As long as you can answer that question in a solid, logical manner, you win. :cool:

Our building comprises of 2 companies, only one of which is getting certified. The other company uses the thread gages, step gages, etc. 90% of the time while the company getting certified may only use them 10% of the time.

Right now the way we know the gages are reading accurately is by a couple ways. Our suppliers use the same gages we use. They need to check their product before the send it to us. Once we receive it, we'll check a small sample. If any discrepancies are found, we'll ship the defective parts back and have them recheck them. If they come back and say everything is fine, we'll then look at the gages. Also, certain gages we use more than others, such as 1/4 inch NPT gages. We have approximately 4 of those gages. If all 4 read the same, then we know they are all good. If one reads differently than the other 3, and so on, we know something isn't right.

We have certifications for all the gages when we bought them. However, we have not had them recertified. If they are really out of tolerance, we would rather buy new gages than pay someone to tell us we need to buy new gages anyways.

Do you have thread gage masters?

No we don't.

Good posts on this.

Also, if you get a chance, you might want to surf the other threads on calibration frequency. There is a fountain of information. Some of the threads are at the bottom of your post (at the very bottom).

What calibration frequency you set (barring industry/regulatory/customer requirements) is yours to choose. You will need to assess risk. Basically how risky is it should this item be out of tolerance? The lower the risk, the longer you can go between intervals.

I would recommend having your identified instruments on a cycle of some sorts for calibration. I understand that it seems wasteful paying for a "failing" calibration. However, it is important to know the magnitude of the calibration error. It may not matter, but then again, it will. If you just toss them, you don't know how much error they were contributing to your measurement process.

If I understand your posts correctly, there are several areas for potential error. You have sampling error, measurement error on the part of the customer, and measurement error at your facility. If you do not assess the uncertainty of your measurement instruments, then you have just added another uncertainty. This could be increasing your probability of acceptance/rejection errors.

If they are really out of tolerance, we would rather buy new gages than pay someone to tell us we need to buy new gages anyways.

I'd go for that too, if it wasn't a chicken and egg thing. For the facility that is being registered, comparing gages as you described will not qualify as calibration. Using your supplier to verify your gaging, won't pass muster, either. Calibration is a very specific process, with traceability to a national standard. How often you calibrate is your call - but how you calibrate is going to be easily determined to be correct or not. :2cents:

We deal with pressure, temperature, and force related products. If a gauge isn't seated properly (bad threads), we will catch that as we calibrate the gauges via Test Gauges. I'd say it's very rare for us to use these thread/plug/step gages.

For the most part, all gages belong to the other company because they use them much more than we do. Whenever we need them, we'll borrow them. The other company does sampling on incoming material. We only use these gages when something doesn't work for us here to diagnose the problem.

All gages are traceable to NIST and for the most part, we have documentation saying so because when we receive new gages, certs come with them.

And I didn't mean that we use other gages to calibrate a gage. Those 4 NPT gages are used incase some read differently. It's more of a verification to see if they are in fact out of calibration.

If you try 4 lightbulbs in a socket, and three of them work, you know that the socket works and 75% of the bulbs work. You just found the defective gage that needs recalibration or buy a new one.

Our company implement device calibration once per year.

I realize the cost of calibration can be high. You must ask yourself what the cost of bad product is to your company. If you are only concerned with an upcomming audit, make sure that none of the gages you borrow are on the premises during the audit. To be in compliance with ISO you could put the gages on a usage cycle. Another solution would be to get a set of gages for your side of the business. Yoiu would then know how much use the gages actually got.

Hope all this helps. Have a great day.

It's not about having bad product. We know whats bad without the use of any gage. However, the problem is we do use some gages, but they are not up-to-date with calibration/verification.

We can't "remove" gages from the premises because we share the same building/QC lab with the other company. Putting the gauges on a usage cycle would also be difficult. We could go weeks without using a thread/plug/step gage for our side of the business.

This is a tough one...

Forgive me in advance if this seems short, but I don't understand what the difficulty is.:confused:

if their accuracy/error doesn't matter, lock them up and mark them off as non-calibrated.

If it matters, then have them calibrated by a competent lab. Put them on an annual cycle (or two years, or whatever you choose). Then, adjust the cycle accordingly with how they perform.

Several issues have come up in this thread.....

First, the best document to help figure out the calibration cycle is RP-1 available from NCSLI at http://www.ncsli.org

Second, have the devices calibrated by a lab accredited to ISO/IEC 17025 by a recognized accrediting body, of which there are four based in the U.S., they are: IAS, NVLAP, A2LA, and ACLASS.

Third, understand that calibration done properly is not cheap. Shop around, but if you get a quote that is way cheaper or way more expensive than the others, suspect them.

Last, every cal lab in this country claims to be "Traceable to NIST", but without the specific documentation of the traceability chain, and stated uncertainties, there is no traceability.....in other words, no evidence means no traceability, no matter what the cert claims.

Hope this helps.

Hershal

I guess what I'm basically asking is, is there any requirements/guidelines that state when gages should be calibrated?

7.6 a) be calibrated or verified at specified intervals...what if I specify never?

Some of our thread/plug/step gages date back to 1994. We have since bought new and additional gages, but they have not been calibrated in a long time.

Here is a quote from a similar thread: http://elsmar.com/Forums/showthread.php?t=18590&page=2

One thing to remember is that if you have an item that requires calibration, you don’t necessarily have to calibrate it depending on how it’s used. Even a device like a precision micrometer doesn’t have to be calibrated if it’s used for general work only and not used to make qualitative measurements.

Also, an item such as a frequency generator doesn’t require cal if a calibrated frequency counter is used to set it up. Same for a power supply if set up using a calibrated meter. You just have to make sure those exceptions are WELL IDENTIFED!

Our thread/plug/step gages aren't used to make qualitative measurements. They are used to somewhat "double check" that the product was produced to our tolerances. The products should always be checked with gages even before the enter our doors from our suppliers. Make sense?

I am no expert at this, and I have been using this forum to help me with several questions. So let’s see if this helps. Why could you not purchase thread mics to calibrate your plug thread gages internally. You can get them in incremental sizes (e.g. 0 - 1", 1" - 2"), you should only need a set for each size. The sets come with assorted tips for different thread sizes. If you use them only to calibrate your plug gages, you would only have to send the thread mics out for a yearly calibration and you can get the thread spec's from the machinist handbook to know what your tolerances are when you calibrate the plug thread gages in-house. Just a thought like I said I am still learning too.

For clarification what I meant by 'you should need a set for each size', was that a 0 to 1" size would cover all of your threads up to 1"

Yea, there are various routes we could take to have gages calibrated/verified. For these purposes, just wondering if we'll get striked for borrowing another company's gages that have not been calibrated since their acquisition to double check our products/parts? Our consultant is coming back April 30-May 1 to see how far along we are for our third party audit in July. We'll see what he has to say regarding this issue. :)

Yea, there are various routes we could take to have gages calibrated/verified. For these purposes, just wondering if we'll get striked for borrowing another company's gages that have not been calibrated since their acquisition to double check our products/parts? Our consultant is coming back April 30-May 1 to see how far along we are for our third party audit in July. We'll see what he has to say regarding this issue. :)

In my opinion this presents a severe traceability problem. (17025)
My calibration tools (of any kind) must stay within the company.
I need to assure they have not been tampered with in any way.
I cannot do this if they leave my control.
At one time we used to rent out weights. Now if you need say 7000Lb of weights you must also rent the man and the truck to carry them.
Should someone leave something at a customer’s site (yes it does happen and quite frankly I don’t know how) it must be recalibrated and sealed before placed back in service for calibration purposes.
This may be a little overkill for your needs, however you must assure your customers…….

What we do is calibrate all gages used for FINAL inspection. All other gages in the shop are either marked (with a sticker) "for reference only" or made exempt from either catagory by a statement in our Quality Policy. Something like "all tape measures and 6 inch scales,ect. are not used in final inspection and thus are not indivually identified or calibrated...........". We have been ISO 9000 certified for about seven years now and this approach has been accepted by our internal and external auditors.

I'd say that the gages we use are NOT for critical measurements and are not used for final inspection. Like I've said earlier, we rarely use these gages, but we still do occassionally and I'm not sure how to approach that.

When you use these rarely used gauges (by themself), do you:

1. write do wn the value?
2. Reject product based on the results of those instruments alone?
3. Will their result cause a red flag with the customer?
4. Is there a step, specification, etc. in a procedure that depend on the values/ results of the rarely used gauges?

If they matter, they need to be calibrated. Regardless of who they belong to, if their results matter, they need to be calibrated.

If you don't calibrate them, then clearly isolate them and mark them reference only, no calibration required, etc.

Be patient... hopefully we'll eventually get this figured out! :tg:

When certain parts come in, we may check their machining. Using some gages we'll check the tolerances, + or -, according to the Engineering drawing specifications. Write nothing down. Basically a Go/No-Go gage.

Products may be rejected based on if the gage states No Go. Those rejected products/parts may then be sent back to the supplier for reevaluation.

Result will cause a red flag for us and delay any production of a certain product. We'll get it situated with the supplier before it ever reaches the customer.

We calibrate and test 100% of the products we ship out using Test Gauges and other higher end measuring devices that ARE calibrated at set intervals. If anything fails, it doesn't leave. The thread/plug/step gauges we use may be a preliminary check on product/parts before they are sent out to receive additional assembly/welding/machining/etc. They will then come back and we'll calibrate and test all of them when POs arrive.

Tell me if I've been all over the board with this topic because I feel that I have been

O.K. so these gages are not used for final inspection, but for incoming inspection. In that case I'd look to 7.4.3 Verification of purchased product. If you define in your procedures that you use the gage to "ensure that purchased product meets specefied purchased .........",than calibrate it. The auditor might ask you how you check incoming product. I wouldn't say "Sometimes we check them with a _____ gage". You MUST (shall) ensure incoming product meets requirements. Either you use the gage or you don't. If/when you decide to calibrate the gage than you can establish a procedure or work instruction defining when and how.

Used for incoming inspection ONLY IF there is a known problem; previous history with supplier, failing other calibrations/tests, visually detected a problem, etc. Otherwise, incoming product/parts are only visually inspected against the PO or Bill of Lading.

Currently, we make no mention of thread/plug/step gages in our procedures. Only the higher end measuring devices are listed. Basically, the ones with specified intervals of calibration and verification.