FMEA: Visual Detection Rating

[Jim Wynne]

Nice suggestion. But lets see if the customer agrees to sign.

Good luck. Please post back with the results.

 

[jerry_Malaysia]

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.

Totally agree with you Jim.
I had so many annoying experiences with unqualified auditors (customers side and even TS consultant). Glad to have someone whose share the same thoughts with me.

 

[Bev D]

In case you haven't thought of this yet: a categorical data (aka attributes data) MSA can provide the objective evidence to your customer that your rating is 'correct'. Couple this assessment with the controls you have in your system for inspector training and qulaification and control of inspection conditions and you have objective evidence that the detection rating is sustainable...

 

[jasonb067]

I think that there are some other things to consider as well. What are the severity and occurrence ratings. Regardless of individual feelings of visual inspection effectiveness. The severity is low and the occurrence is low then the RPN should be low and this is probably not something an organization should focus their efforts on.

If this is a severity of 9 and an occurrence of 7 (for example) I think visual inspection unacceptable.

I would try to shift the focus away from discussing the rating guidelines and attempt to discuss the details of what this particular operation is.

 

[Jim Wynne]

I think that there are some other things to consider as well. What are the severity and occurrence ratings. Regardless of individual feelings of visual inspection effectiveness. The severity is low and the occurrence is low then the RPN should be low and this is probably not something an organization should focus their efforts on.

If this is a severity of 9 and an occurrence of 7 (for example) I think visual inspection unacceptable.

I would try to shift the focus away from discussing the rating guidelines and attempt to discuss the details of what this particular operation is.

Whether or not visual inspection is appropriate is more a function of the characteristic in question than the severity and detection ratings. Severity and occurrence notwithstanding, sometimes visual inspection is the only option (although I think it would be relatively rare that an item with a high severity rating would be subject to only visual verification due to the nature of the product).

You're right, however, in saying that we need to look at the big picture, and not look at detection ratings separately from the other two.

 

[jerry_Malaysia]

u have the point there jason
but it all depends on whether there are options available other than visual inspection
if visual inspection is the only method, and you have assess the msa to be at satisfactory level, i don't see why it is not acceptable. unless some other method available which is economic and the cost is justifieable

 

[Bev D]

It also depends on what the OP's Customer is actually miffed about. The Customer may truly only be picking on the non-use of 7 per the suggested guidelines of the manual. You know sometimes the customer really only looks for the 'easy to pick out things' because they dont' understand the content; they are only reviewing your submision by some rote checklist of their own making.

 

[jasonb067]

BEV D. Your summary is correct.

The main point is trying to find out what the customer has the exact problem with. Symptom (visual can not be 7) vs. cause (I have a checksheet or blah blah...).

I may be wrong but I am sticking with my statement. There are situations where the sev. and or occ. would be high enough that there is no way I would accept visual inspection (no matter how apparently obvious the feature). Simply stated, it will fail. Everyone looking at this has a delete key and a backspace key on their keyboard. The people that we are giving the responsibility of inspection do not have that luxury. That is my about that.

 

[Bev D]

not disagreeing with your statement as a general comment. Only pointing out that the OP's question doesn't appear to be about the point you are making.

We often go off on tangents that are interesting, helpful, insightful thought provoking etc. and sometimes we go off on tangents that are way off topic. Either way we can occassionally get so caught up in the tangent discussion that we forget to address the OP's actual concern. 'course, I am as guilty of this as the next guy .

 

[Richard Pike]

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

First set the precedent for any argument.

If I have shoes on and I ask you to examine if indeed I am wearing shoes, I am sure that you will find that visual inspection is very effective. If I ask you what size those shoes are then your visual inspection may not be very effective.

So Horses for Courses! Certainly Detection Scales invariably have to be customised according to the nature of what is being detected! If they are not, then a constant high rating will disguise the meaning of the RPN value. i.e artificially disguising the impact of the ratings of Seriousness and Occurrence.

In another extreme example, placing two screws in a container, with color identification clearly highlighting any absense prior to fitment, could be classed as low level fool-proofing thereby justifying a low detection scale.

As for verification of your customized scale - MSA Techniques help, knowing the relevent AQP (sorry for swearing) also helps along with any other method for verifying (or not) the effectiveness of your particular detection method.

One thing is non-negotiable (in my view) The scales provided by AIAG are "examples" and as such they infer that they should be adjusted according to the nature of the product and process.

And for your Customer - they are correct in challenging your scale - however you are incorrect because you were unable to justify that scale!

Hope that helps a little!