Manufacturing Equipment Pressure Gages Calibration Requirements

[bobdoering]

Re: Pressure Gages Calibration

I pretty much agree. I'm just unclear as to why the auditor just summarily wrote up an instrument. It could be important; it may not.

Injection molding machines have 106 gauges on them, most all of them are just used for maintenance. So I'm still unclear if the auditor just saw an uncalibrated gauge and started writing, the auditor found a clear nonconformity within their QMS regarding the gauge(s), or if the auditor may have process knowledge, and knows the gauge is relevant to the process.

Sometimes it is the answer the auditee gives that can create the issue. "I don't know" can open the infamous can of worms... Even worse if nobody knows!

 

[Marc]

Re: Pressure Gages Calibration

Sometimes it is the answer the auditee gives that can create the issue. "I don't know" can open the infamous can of worms... Even worse if nobody knows!

As I said, if the person responsible for the machine can not answer every relevant question they have no business working with the machine or trying to answer questions about it. Sometimes a machine operator may not know, but who ever is responsible for the machine should.

 

[bobdoering]

Re: Pressure Gages Calibration

I have long advocated against labeling each gage that does not need to be calibrated. Looks don't mean a thing. Gages which have to be calibrated should be on a recall list. If the person responsible for the machine can not explain which gages have to be calibrated, and why, and which do not have to be calibrated (and exactly why they don't have to be calibrated), that person has no business being involved with the machine.

If one uses the type of 'label everything' model, one would have to label every uncontrolled document 'Uncontrolled' in some way (as an example) which is a total waste of time.

I find what is worse is when people put "for reference only" on gages because 1) they don't know what they are for, 2) they haven't figured out how to calibrate or verify them or 3) don't feel like paying to calibrate them-ever.

So, yes, things that can be meaningful can be made meaningless.

The explanation of the gage calibration should be clear from the control plan or PFMEA...if someone remembered to consider them for those documents.

I would agree, if you have a rock solid QMS, gage calibration, APQP and PM system, you may not need to label all of the gages. Big "if".

 

[bobdoering]

Re: Pressure Gages Calibration

As I said, if the person responsible for the machine can not answer every relevant question they have no business working with the machine or trying to answer questions about it. Sometimes a machine operator may not know, but who ever is responsible for the machine should.

I agree with that!

 

[Marc]

Re: Pressure Gages Calibration

I find what is worse is when people put "for reference only" on gages because 1) they don't know what they are for, 2) they haven't figured out how to calibrate or verify them or 3) don't feel like paying to calibrate them-ever. <snip>

Labeling gages "for reference only" is something I have seen quite often and it was always because a consultant or book said they should to keep auditors happy.

 

[MACIEK]

Thank You very much for all the responces. You guys realy hellped alot.

 

[Cobblesong]

Yes - logically that makes sense and is likley a best practice.

But it's not what the ISO9001 standard requires. It's the first paragraph of 7.6: "...evidence of conformity of product to the determined requirements."

Hydraulic line pressure isn't going to prove that that required dimension A is Xmm. It will tell you if the machine is capable of getting there, but that's not what the standard requires.

A close reading of 7.6 shows the first paragraph to say 'monitoring and measuring devices', but the third paragraph (which invokes calibration) only say 'measuring equipment' shall be calibrated. It does not say monitoring equipment requires calibration. Further, ISO-9000 vocabulary does not define 'monitoring equipment'. I believe saying ISO requires process equipment gauges requires calibration is wrong. Also, process equipment gauges do not 'provide evidence of conformity of product to determined requirements'. A hydraulic pressure gauge on a brake press is not used to confirm the bend radius on sheet metal can be sold, e.g. noone says 'I know this is bent to 90 degrees because my hydraulic pressure is 800psi. Boy, if it read 750psi this part would be scrap.' Instead we measure the bend with a radius gauge, AND IT'S THIS RADIUS GAUGE THAT REQUIRES CALIBRATION/VERIFICATION!

 

[Sidney Vianna]

I believe saying ISO requires process equipment gauges requires calibration is wrong.

The problem starts when anyone makes overly broad statements, based on a single scenario. The different situations have to be evaluated on a case by case. While your brake press example is a good one to support your case, there are many others where process equipment instrumentation is the key to product integrity. Chemical processes, for example, where certain reactions must occur within tight ranges of pressure, temperature, ph, etc...Critical welding processes, which require close attention to amperage, voltage, etc...In such cases, it is paramount to have accurate readings, which can only be achieved if the associated instrumentation is calibrated.

Another typical mistake, when attempting to interpret ISO 9001, is to consider separate paragraphs of the document in isolation. Most of the requirements are interconnected. For example, ISO 9001 7.5.1 e) connects with 7.6.

 

[Cobblesong]

After several more audits, including a certification for KGS (Korea Gas Safety), I discovered that the calibration requirements for welding equipment is covered under ISO 17662, which validates the point I was making. And I completely agree the standard should be read on the whole with great respect for the intended interrelationships. Interestingly, the burden under 17662 for calibrating a welding machine is much lower than what one traditionally encountered for measuring tools, and this is explicity disclosed in the standard. It's like the authors of 17662 (who I believe to be credible as its an ISO standard), said "We better write something reasonable for welding machines, or someone is going to overreach and apply the calibration requirements for 9001 to them".

 

[Marc]

Also see: Measuring Equipment on Injection Machine should be Calibrated by 3rd party?.