Failure Modes that are Solved by actions already in place!

[Manix]

I am constructing a PFMEA for a product, and I find myself looking at certain process steps, trying to find failure modes and coming up with ones that are already dealt with by 'Good Practice' on the line.

My particular example is that we check the steel chassis of our component using a jig! Now what other failure modes can ther be for 'Inspection of the Chassis'? We visually check it using the jig, is the only failure likely to be operator neglet?

Someone help, I am going round in circles!

Basically if you already have controls in place, do you specify these as actions taken to reduce the severity of failure modes?

 

[db]

I'm not sure I follow you. Are you looking for failure modes in just the inspection process? Is so, ask what could go wrong with the process? Can the chassis be placed in the jig incorrectly? Can the jig (or any part of it) move, thereby making the inspection void? Does the jig show all possible chassis failures (color, weight, poor welds, etc)?

In any case I do not think any controls of the inspection process can reduce the Severity of the failure. They might bring the Detection down to a "1", and maybe even influence the Occurrence, but I doubt they will change the Severity rating.

 

[Manix]

I guess I am looking for failure modes in the inspection process. It's a G/NG and I believe it performs it functions of detecting non conforming product very well.

The point I was really getting at was, if the jig that is in place, is already in place, then do I specify this as a result of my Failure Mode analysis, despite the fact that it has been implemented as a standard set up procedure!

I know this is a hard one to follow, I am finding it difficult to explain!

Thanks for your input.

 

[db]

The point I was really getting at was, if the jig that is in place, is already in place, then do I specify this as a result of my Failure Mode analysis, despite the fact that it has been implemented as a standard set up procedure!

I don't think so. I think it would be listed as part of your current process controls, if anything.

My thinking is that the use of the jig would be a process step in the FMEA. And part of the FMEA would be asking questions about potential failure modes with the jig, which relate to my earlier questions.

 

[Bev D]

The point I was really getting at was, if the jig that is in place, is already in place, then do I specify this as a result of my Failure Mode analysis, despite the fact that it has been implemented as a standard set up procedure!

Isn't the jig just your detection of something that can go wrong with the process? Then what you're looking for is the detectability of the jig - does it catch th edefect all of the time or rarely?

 

[Bill Ryan - 2007]

I guess I am looking for failure modes in the inspection process. It's a G/NG and I believe it performs it functions of detecting non conforming product very well.

The point I was really getting at was, if the jig that is in place, is already in place, then do I specify this as a result of my Failure Mode analysis, despite the fact that it has been implemented as a standard set up procedure!

I know this is a hard one to follow, I am finding it difficult to explain!

Thanks for your input.

Welcome to the Cove.

A couple of Failure Modes I have used are "Operator accepts nonconforming product" and "Operator rejects conforming product". When setting up the Process Flow Diagram, I break out the "inspections" into separate "steps". The Failure Modes of the inspection operations are then addressed in those steps. Does that make sense to you?

 

[qualitytrec]

how I deal with your situation if I understand it right is like DB was saying. I set my detection rate according to the jig or fixtures MSA findings then document it through the control plan. The jig is set to control certain failures. the failures should be on the FMEA and the control plan should list the failures with the jig as a control.

Mark

 

[Caster]

We were faced with something similar. We were improving our FMEA by going back to "take credit" for things that we already did without formal use of an FMEA.

What we would do is to first state the problem without the fixture, and create a (high) RPN. Then we would suggest the fixture as an improvement. After the fixture is in place, the new RPN is lower.

Now you can decide if additional action is required to reduce the RPN more.

We have found dozens of good improvements were implemented before we thought to add them to the FMEA.

Our Recomended action column now looks a whole lot better since it shows more of the the history of changes we made.