How to verify profile gages provided by customer

Hi Everyone,

This is my first post to Elsmar Cove.

I am a dimensional metrologist at a plastic injection molding company that makes quite a bit of automotive related plastic parts. Some of these parts are inspected by a production gage that checks the outer profile, or silhouette, all the way around the part. These "drop gages" are essentially go, no-go gages that verify that the parts haven't exceeded a maximum or least material boundary specified by a profile tolerance on the part drawing. Please review the inserted images. As you can see, these gages were machined out of aluminum. A quality inspector would simply attempt to place the part in each of the machined aluminum pockets. The part is required to fit into the larger oversized pockets, and resist fitting into the smaller undersized ones.

A large number of gages of this style were created and provided to us by our customer and I have been tasked with inspecting them. Unfortunately, there is no CAD information available that describes the shape of the various profiles that were used to CNC these shapes. Hence, there is no reference standard by which I can verify these gages. What is our company's responsibility in this context? I am not particularly well versed in ISO standards, but I have been told by my colleagues that we must inspect these gages to remain ISO compliant. However, without our client's assistance, I don't see what we could meaningfully check on these items. Would a simple periodic visual inspection for dents, nicks, etc suffice?
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From what I understand, you have numbers of these gauges that are being used in go-nogo testing of products.
You are also mentioning "ISO" requirements, and you are wondering what you need to do to comply with these.

First, there are many ISO standards that might apply. Since you did not state a particular ISO standards we'll look at the granddaddy of them all, ISO 9001 This is the section of ISO 9001 that most applies to your situation: General
The organization shall determine and provide the resources needed to ensure valid and reliable results
when monitoring or measuring is used to verify the conformity of products and services to requirements.
The organization shall ensure that the resources provided:
a) are suitable for the specific type of monitoring and measurement activities being undertaken;
b) are maintained to ensure their continuing fitness for their purpose.
The organization shall retain appropriate documented information as evidence of fitness for purpose of
the monitoring and measurement resources.

Your case is using these gauges to measure parts to see if they are within acceptable size boundaries, so this applies.
a) states that these gauges must be suitable to the purpose, the company that owns them has determined that they are.

Your roll falls under b). You are trying to determine whether or not they are continuing to be fit for the job.
This is where you need guidance from your customer. They need to determine what makes this gauge fit for their purpose.
If it is dimensional accuracy, then they will need to provide critical measurement tolerances.
If it is only a visual inspection to determine fitness for use (dents, nicks, burrs, etc.) they will still need to tell you what is acceptable and what is not acceptable so you can make an independent determination of fitness.

Your customer is concerned about the last line of the quoted section above. They must retain your results that determined fitness for use.

At this point there is nothing you can do with these on your own. If your customer wants you to determine whether or not these are fit for use then they must give you the accept / reject parameters for your inspections.
Thank you for your response, dwperron!

If the customer is un-willing to provide guidence, how can I protect myself from an ISO non-conformance regarding this matter? We are a Tier 2 supplying a Tier 1 automotive supplier. My thought was to put something in writing stating that the customer is responsible for inspecting these particular gages and maintaining the associated records. Is that a reasonable course of action?
You are not going to receive a non-conformance unless you "calibrate" these without guidance from the customer.
I would return them to the customer without calibration until they provide you with what they are expecting for results, and the pass / fail parameters for these. That is how you protect your organization.

If you are attempting to comply with ISO/TS 16949 you have additional issues. As an external lab you would need to be either ISO 17025 accredited for these calibrations, or you will require documentation from your customer that you are acceptable to them.
Then you will have a lot more specific requirements in your reporting of results. You would best look at ISO/TS 16949 section 7.1.5 before you proceed.


Looking for Reality
were created and provided to us by our customer
If you don't have another measure of what the gages are supposed to be, you really don't have a choice but to have your customer vet them as fit for use. Do you have direct contact for the customer SQE? See what they think and how they suggest to proceed...if nothing else it may give you access to the drawings so you can have the gages verified....or even easier, an email saying "They are good, keep using those".


Involved In Discussions
However, without our client's assistance, I don't see what we could meaningfully check on these items.
Your situation clearly would benefit from some communication and clarification with your client.

However, in terms of what would be meaningful to check, more than inspecting them I would ask: do the gages accept good parts and reject bad parts? In the automotive industry you would answer that with an MSA attribute gauge study. I would opt for signal detection.

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