Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

You need to decide what defines a Failure Mode. In my methodology, the Failure Mode would be "Porosity - Excessive". One of the Effects could be "Joint fails strength test" (or something like that). A Potential Cause could be excessive voltage.

You could also have the Failure Mode as "Excessive voltage" with one of the Effects being "Excessive porosity". Now your Potential Causes would deal with the reasons there is excessive voltage present.

Pretty simplistic (and possibly way off the mark :notme: ) but does it help you out?

Try this: Potential failure mode: bald tires. Potential effects of failure: blow out or slide off rain slick road into ditch, rolling over a few times. Injury or death. Severity: 10. (even more simplistic)

Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

Bill and Bob have given good advice, but I'll give it a bit of a different perspective. I think that when you're dealing with a process FMEA, the failure modes should describe ways that the process might fail, and the effects should be the output results. In other words, in your welding example, what are the process characteristics that control porosity? Failure to control those characteristics can result in porosity, so if you describe the failure mode as failure to control them, and the effect as the resulting porosity, you're more likely to come up with ways to prevent the defects from happening.

Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

In the Ford handbook on FMEA a good help is provided for this problem.
You have to put the items on a timeline like in the example attachment.
The example is part of a training we are providing for FMEA facilitators.

Best regards and I hope this helps,

Antoine

Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

Failure modes (reason) - porosity, deformation, inadequacy
Failure effect (outcome) - breakage or collapse

I find its easier to think backwards sometimes. Think of all the defect outcomes (effects) and then for each one, think of all the things that may have caused each outcome (modes).

I say this all the time but using a root cause analysis will generally get you all your answers no matter what youre doing. Instead of speculating what may have caused a defect...list all potential defects, then work backwards and list what caused the defects.

Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

I think that

Potential failure mode for this is setting problems like current, distn ,etc.

While effect of potential failure is porosity or rest of defects?

I agree with most of the guidance given so far. The failure mode should be defined by the boundary of the system you are covering. The effect however should be as far downstream as you can see. So porosity isn't the effect. The effect could be (for example):
Customer rejection - visual aspect
Weld leaks - pressure loss - no function
Weld leaks - escape of combustible gas - major disaster

So, IMHO, the failure mode is the defect caused by the weld process - porosity and the effect depends on the need for the weld.

Hope this helps.

I agree with most of the guidance given so far. The failure mode should be defined by the boundary of the system you are covering. The effect however should be as far downstream as you can see. So porosity isn't the effect. The effect could be (for example):
Customer rejection - visual aspect
Weld leaks - pressure loss - no function
Weld leaks - escape of combustible gas - major disaster

So, IMHO, the failure mode is the defect caused by the weld process - porosity and the effect depends on the need for the weld.

Hope this helps.

Here is an example:

Failure mode: Disaster
Effect: Aftermath
Stijloor.

This is my understanding.

Look at the Process Model:

Input-Activity(Process)-Output. Identify the controls, if known already.

First step: I prepare the Process Flow Chart (start to finish)

For each step, I ask the following questions:

1. What can go wrong? ( Look at the outputs)
1.(a). What all can go wrong?

This is in turn a list of all types of non-conformances - known OR potential

So my list of failure modes is ready.

2. What if it goes wrong?
2.a. What if they go wrong?

So my list of effects is ready

3. Why should it go wrong?
3.a. A deficiency in 'CONTROLs' ( various)
3.b. A deficiency in the Inputs ( all)

So my list of causes is ready.

I then ask the participants to look at the NC / CC Register for all what already has happened.

Now I ask them, can any of these or all of these happen in the new case also?

With these, I get back to my FMEA guidelines and proceed further.


Is my understanding correct, please comment ?

This is my understanding.

Look at the Process Model:

Input-Activity(Process)-Output. Identify the controls, if known already.

First step: I prepare the Process Flow Chart (start to finish)

For each step, I ask the following questions:

1. What can go wrong? ( Look at the outputs)
1.(a). What all can go wrong?

This is in turn a list of all types of non-conformances - known OR potential

So my list of failure modes is ready.

2. What if it goes wrong?
2.a. What if they go wrong?

So my list of effects is ready

3. Why should it go wrong?
3.a. A deficiency in 'CONTROLs' ( various)
3.b. A deficiency in the Inputs ( all)

So my list of causes is ready.

I then ask the participants to look at the NC / CC Register for all what already has happened.

Now I ask them, can any of these or all of these happen in the new case also?

With these, I get back to my FMEA guidelines and proceed further.


Is my understanding correct, please comment ?

Looks good to me, with one possible exception: when considering the potential failure modes for each operation, you should assume that the input is "good," and thus concentrate on potential failures caused in that particular operation. The exception would be receiving inspection, where it's not known whether the material is good or not. In that case, you should look at ways in which evaluation of the "goodness" of the material might be wrong, in addition to other potential failures caused within the process. It's not a good idea to ascribe causes to extrinsic factors (those which you don't directly control) such as supplier errors.

Hi ,

Recently my operation manager asked to come out with FMEA for our welding process. when i'm going to through the FMEA table, i confused with potential failure mode and potential effects of failure. for a example our welding always produce porosity defect. Porosity will be our welding process potential failure mode or potential effects of failure? please give me your opinion. thanking in advance for your kindness.

Rgds,
Murugan

Per AIAG FMEA Rev. 3 page 41

"Typical failure modes could be but are not limited to:
Bent, Cracked, Handling damage, Surface too frough, Open circuited, Burred, Hole too shallow, Dirty, Defiormed, Short circuited, Hole off-location, Hole missing, Hole too deep, Surface too smooth and Mis-labeled."

Potential Effect(s) of Failure

"For the end user, the effects should always be stated in terms of product or system performance, such as:

Noise, Erratic operation, Unpleasant odor, Leaks Poor appearance, etc."

If the customer is the next operation

Cannot fasten, Cannot mount, Does not fit, Inoperative, etc."

Hope this helps.