FMEA: Visual Detection Rating

[Quality-1]

Hi

One of our customer is not happy that we have a Visual Rating of 2 & 3 on our FMEA. According to the customer, standard rating for visual inspection is 7. Could someone please comment.

Thank You

[Jim Wynne]

In Reply to Parent Post by Quality-1

Hi

One of our customer is not happy that we have a Visual Rating of 2 & 3 on our FMEA. According to the customer, standard rating for visual inspection is 7. Could someone please comment.

Thank You

The detection rating should be based on experience and not on the whims of a customer, unless such whims are unavoidable. If you've conscientiously determined that the likelihood of detecting a specific NC condition is rationally reflected in your detection rating, you should explain that to the customer, and provide evidence.

[Quality-1]

Thank You for the valuable comment. The only think I am concerned is that the customer is suggesting that in FMEA book for Visual the detection is suggested at 7 (pg 100 of FMEA-4)

[Howard Atkins]

This has been for some time the value.
Experiments show that visual inspection is only some 85% effective. Another problem is that with manual operations there is always a chance of the part missing the station.
I agree with your customer.
Some customers mandate that you use the values in the handbook

[Jim Wynne]

In Reply to Parent Post by Quality-1

Thank You for the valuable comment. The only think I am concerned is that the customer is suggesting that in FMEA book for Visual the detection is suggested at 7 (pg 100 of FMEA-4)

You should remind your customer that the AIAG manual consists of guidelines and not requirements. If you look at page 2 of the manual, you'll see that the first sentence says:

This manual introduces the topic of Potential Failure Mode and Effects Analysis (FMEA) and gives general guidance in the application of the technique.

(My emphasis)

Moving ahead to page 99, you'll see this with regard to Suggested evaluation criteria:

The team should agree on evaluation criteria and a ranking system and apply them consistently, even if modified for individual product analysis. Detection should be estimated using table Cr3 as a guideline.

(My emphasis again)
There is not necessarily any reason to assume that the likelihood of success of visual inspection is "very low," as it's characterized in table Cr3 on page 100. The efficacy of any type of inspection is wholly dependent on the individual product characteristics being inspected and such things as objective criteria and operator training.

There will be instances where customers who don't like to think about what they're doing will require you to cleave to the methods of classification in the manual, regardless of whether it makes any sense to do so. Nonetheless, before doing something that doesn't make sense you should at least try to reason with the customer, and show them that your method is better, and conscientiously reflects your concerns for the conformity of their product.

[Quality-1]

Gentlemen

Thank Youf or the valued comments. I appreciate you both for giving me a different perspective.

I will discuss this with my team.

[Jim Wynne]

In Reply to Parent Post by Howard Atkins

This has been for some time the value.
Experiments show that visual inspection is only some 85% effective. Another problem is that with manual operations there is always a chance of the part missing the station.
I agree with your customer.
Some customers mandate that you use the values in the handbook

Sorry Howard, but I have to disagree. There's no rational way to apply a value of 85% (or any other number) to all processes. The old bromide about 100% inspection being x% effective has no widely-applicable empirical basis.

There are processes where visual inspection might be used to determine whether a thing is red or blue from a group of five objects, and others where there's a fast-running automated process involving thousands of items and subjective criteria. Most processes fall somewhere in between those extremes, and the likelihood of success of visual inspection will vary accordingly.

[dknox4]

In Reply to Parent Post by Jim Wynne

You should remind your customer that the AIAG manual consists of guidelines and not requirements. If you look at page 2 of the manual, you'll see that the first sentence says:
(My emphasis)

Moving ahead to page 99, you'll see this with regard to Suggested evaluation criteria:
(My emphasis again)
There is not necessarily any reason to assume that the likelihood of success of visual inspection is "very low," as it's characterized in table Cr3 on page 100. The efficacy of any type of inspection is wholly dependent on the individual product characteristics being inspected and such things as objective criteria and operator training.

There will be instances where customers who don't like to think about what they're doing will require you to cleave to the methods of classification in the manual, regardless of whether it makes any sense to do so. Nonetheless, before doing something that doesn't make sense you should at least try to reason with the customer, and show them that your method is better, and conscientiously reflects your concerns for the conformity of their product.

If you do try the "reason with the customer" route and happen to be successful (I've tried this route many times, many subjects, FMEA methodology being one unsuccessful conversation) do yourself a favor and draft a letter of agreement and have them sign it. This way when the next customer rep (they change often in my experience) comes-a-calling you can show that the issue has been handled. It's been my experience that if you can get one rep to sign/agree officially to a deviation from the script, others will not force you to reverse. IMO, 98% of the issue is that each rep does not want to assume a risk by deviating form prescribed norms no matter how much logic is involved. Every now and then though, you get someone that knows what they are doing and is not afraid to take action.