DFMEA Failure Mode Groups 3

[uwbsme]

Hello,

I am conducting a DFMEA for a new product. It is a commercial appliance type product. I am trying to narrow down failure modes into groups to use as a guideline for future analysis.

Does anyone have a list of failure mode groups (i.e. mechanical, electrical, etc.) to help in the brainstorming process?

Thanks.

 

[moon161]

I don't remember grouping it like that, but there are no hard and fast rules. Use logical groups that help you prepare and review a thorough FMEA. I did a few for medical devices. For a low air loss flotation mattress, I remember we went by major components/assemblies
Mattress:
Top Sheet
failure modes
Shell
failure modes
Air Cell
failure modes
Manifold
failure modes
CPR Vent
failure modes

When it's done, it should help you have a clear picture of the function and safety impact of each part of the product.

Your important things are: thorough, logical, and consistent. This protects the design & risk mitigation processes, and yourself. When something goes wrong, it should all be there:

Neutral safety switch
fails closed
car runs uncontrolled & kills somebody
occurrence
severity
risk index
brake interlock- driver must have foot on brake to start
mitigation index
revised risk
fail safe NSS design
mitigation index
revised risk

 

[MintJulep]

Another approach is to start from stress sources. Temperature, vibration, shock, wear, voltage spikes, water, wear, contamination, etc.

Then ask How could temperature affect component 1? How could vibration affect component 1?

 

[TheTick]

Also keep discipline w.r.t. DFMEA &MFMEA. DFMEA assume everything is made right.

 

[KENAT]

There are references which give suggested probabilities of certain failures for different types of parts and failure modes. Might be worth looking into.

One way to look at it is what are the 'worst case' end results and look at all the things that could lead to that.

For instance, I was once involved with FMECA (Failure Mode Effect & Criticality) analysis of a aircraft practice store. The 3 catastrophic end results were falling off the aircraft in flight, detonating while on the aircraft, or detonating if dropped while being handled on the ground plus a kind of combo failure if it fell off the aircraft while it was on the ground.

We looked at all the potential ways that could happen/the chain of events that could lead to it.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[GregLocock]

If you've got some Systems Engineers drifting around the place (probably the ones wearing velvet smoking jackets and listening to Bach) they may have some good ideas on how to partition your FMEA. I wouldn't get too upset about it if not, the main idea is to capture the experience of your experienced people with similar products. You could always try the old fishbone classifications, methods, materials and so on.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[moon161]

I used to have a velvet smoker! I've got the well tempered klavier, vol.2 someplace, think it's at my parents. Used to have clove cigs and a beret as well.

 

[tbuelna]

uwbsme,

Here's a good basic reference for mechanical system reliability that is used in the aero industry. It may provide some guidance:

http://www.everyspec.com/USN/NSWC/NSWC-06_RELIAB_HDBK_2006_15051/

Hope that helps.
Terry

 

[ramiro1]

You have asked the typical question that new engineers ask when approaching a FMEA.
I have tought young engineers that the most effective way of approaching the task is to:
1 ) Identify the energy sources that are used in the product.i.e. how much energy has to support or generate.
2) follow the energy path trough the produt.
3) ask the following questions a) what will happen if the enrgy is withdrawn. What will happen if the enrgy is increased.
4)The energy sources are: Gravity,heat, mechanical, electrical, chemical.