Thread Gages

[LesPiles]

Context: We are a producer of industrial battery chargers. These chargers physically appear as a protective envelope which is as big as an industrial refrigerator. The enclosure is assembled by us. On the different metal panels constituting the enclosure, there are small cylinders with internal thread.

Non-compliance: During an internal audit, the auditor saw an unidentified, uncalibrated thread gage kit, and he also believed that some of these gages were worn. Its exact verbatim is as follows: “For the receiving inspection of mechanical components, the threads are checked with threaded ends, not with valid / calibrated thread plug (go-no/go) and this, for all sizes of threads”. He based his NC on requirement 7.1.5.1 Measurement Traceability, which states: “The organization must maintain appropriate documented information demonstrating the adequacy of resources for monitoring and measurement. »

The Question: Is procuring ouserlves with valid / calibrated thread plugs (go-nogos) for all sizes of threads checked the recommended course of action? These gages are probably very expensive. This equipment only serves to “validate” to a certain extent whether the supplier has the metal panels with the right threads e.g. we don’t need precision as in the aviation industy !

Thanks in advance to anyone who can enlighten me!

LesPiles

 

[mhannon]

If you are ISO 9001, and you are making a pass/fail measurement of the threads, yes your gauges need to be calibrated.
If these are industry standard threads and not some unique custom thread, a double ended Go/No-Go thread plug gauge with calibration cert is about $150.
I do not know of any other way to verify those threads other than a calibrated thread plug gauge.

If you aren't using a calibrated tool to verify the threads, why check them at all? You have no faith or certainty in your measurement.

 

[qualitystartup]

In my opinion, if you are only validating what the supplier has sent prior to assembly, I feel like you could get away with a "For Reference Only" or "Calibration Not Required" sticker on these gauges.
I think it could still be considered an NC in the fact that you have gauges not labeled or identified.

 

[mhannon]

I look at it like this, These panels are being delivered to you from your supplier. They go to your incoming inspection department to be accepted or rejected. You are checking multiple things including the threads. If the part passes all checks, it is moved to inventory. If it fails, it is rejected and you initiate a NCMR/SCAR to address the supplier.
If you are using an uncalibrated gauge to verify the threads, how can you have any assurance you are not accepting bad product or failing good product? If it isn't calibrated, I wouldn't check it at all. Why bother?
Also, how can you give a corrective action to your supplier for non-conforming threads if you cannot prove they are non-conforming? Again, might as well not check the threads at all, since nothing can come of it.

 

[qualitystartup]

I look at it like this, These panels are being delivered to you from your supplier. They go to your incoming inspection department to be accepted or rejected. You are checking multiple things including the threads. If the part passes all checks, it is moved to inventory. If it fails, it is rejected and you initiate a NCMR/SCAR to address the supplier.
If you are using an uncalibrated gauge to verify the threads, how can you have any assurance you are not accepting bad product or failing good product? If it isn't calibrated, I wouldn't check it at all. Why bother?
Also, how can you give a corrective action to your supplier for non-conforming threads if you cannot prove they are non-conforming? Again, might as well not check the threads at all, since nothing can come of it.

I see your point and agree with you depending on the situation.

My take on OP's post, was they are basically verifying they have the correct panel in front of them to assemble, not necessarily checking the work. I could very well be misinterpreting the initial post.

But, if they are going through and checking all of the threads to make sure they are correct, I can get behind your point 100%. There is no point in checking the suppliers work if you aren't using a calibrated gauge. And, as you stated, they aren't terribly expensive if you are ordering standard sizes.

 

[qualitymanagerTT]

The Question: Is procuring ouserlves with valid / calibrated thread plugs (go-nogos) for all sizes of threads checked the recommended course of action? These gages are probably very expensive. This equipment only serves to “validate” to a certain extent whether the supplier has the metal panels with the right threads e.g. we don’t need precision as in the aviation industy !

Thanks in advance to anyone who can enlighten me!

LesPiles

What's the risk if you assemble the panels / enclosures and the threads do not hold?
I fully agree with mhannon - if you're not calibrating your gauges, how will you know if your supplier is providing NC products, or if their products are good but your gauges are out of calibration if there is a difference? (your post did say that the auditor thought some were worn)

 

[Quality-Nation]

He based his NC on requirement 7.1.5.1 Measurement Traceability, which states: “The organization must maintain appropriate documented information demonstrating the adequacy of resources for monitoring and measurement. »

Just to clarify the context of the audit: was the internal auditor required to audit the control of measuring equipment in the scope of their audit? Is the audit criteria for the audit that requirement and the standard. Were they assigned to the audit because they are competent to audit the preceding?

 

[Golfman25]

Context: We are a producer of industrial battery chargers. These chargers physically appear as a protective envelope which is as big as an industrial refrigerator. The enclosure is assembled by us. On the different metal panels constituting the enclosure, there are small cylinders with internal thread.

Non-compliance: During an internal audit, the auditor saw an unidentified, uncalibrated thread gage kit, and he also believed that some of these gages were worn. Its exact verbatim is as follows: “For the receiving inspection of mechanical components, the threads are checked with threaded ends, not with valid / calibrated thread plug (go-no/go) and this, for all sizes of threads”. He based his NC on requirement 7.1.5.1 Measurement Traceability, which states: “The organization must maintain appropriate documented information demonstrating the adequacy of resources for monitoring and measurement. »

The Question: Is procuring ouserlves with valid / calibrated thread plugs (go-nogos) for all sizes of threads checked the recommended course of action? These gages are probably very expensive. This equipment only serves to “validate” to a certain extent whether the supplier has the metal panels with the right threads e.g. we don’t need precision as in the aviation industy !

Thanks in advance to anyone who can enlighten me!

LesPiles

So only you guys know the requirements of your processes and products. In my view, it is for your company to decide what is or is not needed. Now the measurement sticklers will come and say "why measure with an uncalibrated device, how do you know, etc." Answer is easy -- not everything needs to be measured to a tolerance with precision. In this case, it sounds like you're doing a simple verification, not a precision inspection -- did they send us the right parts? You're looking for epic failures, not +/- .0001. So you're looking to see if they sent 1/4-20 vs 3/8-16. So what is the value of "calibrated go/nogo thread plugs" in that situation -- zero. If you get to your assembly line and the screws don't fit, you can address it then -- and presumably, you have determined the likelihood and level of risk that would involve, consequences, delays, etc. We are, after all, supposed to be using risk-based thinking, right?

We have been dealing with this question for years. We order steel coil, slit to a specific width. There is no specified tolerance for our purposes -- providers provide +/- .005. We check with a steel ruler -- looking for epic failures, not +/- 005 precision. We want to know that they sent us 2.75 wide and not 3.00 wide. That's it. We do not, under any circumstances need a "calibrated" steel ruler to make that verification. Yet we have had auditors tell us we do.

 

[Jim Wynne]

It sounds to me like the thread gages are being used to identify and not to measure. If this is the case, use a screw or bolt and get rid of the gage(s).

 

[ChrisM]

Are the enclosures to your specifications/drawings, or are they proprietary off-the-shelf items?
The advice offered by Golfman25 and Jim above is IMHO excellent.