What are Comfort and Convenience Items on a Design FMEA

#1
Hi, I am start teaching FMEA since 2002 ( from FMEA 3rd Edition to 4th Edition ). But there is still an arguement on Loss of secondary function (vehicle operable, but comfort /convenience functions inoperable)
( as refer to Severity Table ).

Lets take an example failure - Air Condition not functioning. Herewith some TS auditors' comment.

Auditor 1
From Customer Effect - you should rate it under 8 because loss the primary function of air condition even vehicle is operable ( but it against the 4th edition table ).

Auditor 2
From Customer Effect - you should rate it under 6 because loss of secondary function and vehicle is operable. Air Condition is only Secondary function for the vehicle. In other words, unless you are designing engine parts otherwise the failure only can reach as high 6 )

Auditor 3
ANYTHING ALSO POSSIBLE, it depends........ ( Seem like not answering at all ).

NOW, my question is.... when we are designing an System or Sub System or Component, do we look at the failure of its own or whether failure to the vehicle? If failure of its own, then it should be rated 8 as primary function is loss but if failure to the vehicle, then it should be rated 6 as it is considered as secondary function to the vehicle ( off course, except engine itself )..

What do you think as an expert? Please give your solid comment ( not again like.... it depends.... ).:bonk:
 

adamsjm

Inactive Registered Visitor
#2
Unfortunately, it does depend.
If the HVAC failure only affects the HVAC system, then the comfort of the operator is lost and the severity would be a 6.
However, there are some situations in the off-road equipment industry where the machine must be shut down if the HVAC system (specifically the air conditioning) does not function. In this case, the result is “vehicle is not operable” and a severity of 8.
The Failure Mode should be written specific enough to point out these differences.
 
#3
Unfortunately, it does depend.
If the HVAC failure only affects the HVAC system, then the comfort of the operator is lost and the severity would be a 6.
However, there are some situations in the off-road equipment industry where the machine must be shut down if the HVAC system (specifically the air conditioning) does not function. In this case, the result is “vehicle is not operable” and a severity of 8.
The Failure Mode should be written specific enough to point out these differences.
Hi ADAM,

Can I conclude the FMEA 4th edition - Severity - Customer Effects, now analyse the part design failure as part of VEHICLE. Means, if the part causes the VEHICLE inoperable, then rated 8 and if the part only contribute comfort or convenience / secondary function TO THE VEHICLE (while VEHICLE still operating), it should be rated 5 or 6? This definition is totally different from FMEA 3rd Edition ( if you read carefully the definition for rank 5-8 ).

FMEA 3rd Edition mentioned - VEHICLE / ITEM INOPERABLE (8).. and VEHICLE / ITEM OPERABLE BUT COMFORT AND CONVENIENCE ITEMS INOPERABLE.. If we base on the FMEA 3rd Edition, RANK 8 include both VEHICLE and ITEM itself...( I hope you understand what am i trying to say ..) Means, now I can inform this GOOD NEWS for my customer that the severity that they determined last time (8) can be downgraded (6) as long as the VEHICLE is operable. AND, they can now drop the SPC since it is not SPECIAL CHARACTERISTIC anymore..

TKS..:applause:
 

adamsjm

Inactive Registered Visitor
#4
FMEA 3rd Edition mentioned - VEHICLE / ITEM INOPERABLE (8).. and VEHICLE / ITEM OPERABLE BUT COMFORT AND CONVENIENCE ITEMS INOPERABLE.. If we base on the FMEA 3rd Edition, RANK 8 include both VEHICLE and ITEM itself...( I hope you understand what am i trying to say ..) Means, now I can inform this GOOD NEWS for my customer that the severity that they determined last time (8) can be downgraded (6) as long as the VEHICLE is operable. AND, they can now drop the SPC since it is not SPECIAL CHARACTERISTIC anymore..
There is no difference between Ver. 3 and Ver. 4. The Item mentioned refers to a System which may not be a vehicle. If we performed a DFMEA on a House (Item) the loss of the roof would be a Severity of 8 while the loss of Air-Conditioning would be a loss of comfort, Severity of 6. As far as it not being a Special Characteristic with a Severity of 6 vs 8 - that would depend upon how you and you customer rate risk. A Severity-Occurrence matrix method for assigning risk requires the understanding and assignment of Occurrence. While SPC is the most common method to mitigate risk, it is not the only method. Error-proofing, incoming inspection results, and other methods can demonstrate heightened control.
 

Jim Wynne

Super Moderator
#5
Hi, I am start teaching FMEA since 2002 ( from FMEA 3rd Edition to 4th Edition ). But there is still an arguement on Loss of secondary function (vehicle operable, but comfort /convenience functions inoperable)
( as refer to Severity Table ).

Lets take an example failure - Air Condition not functioning. Herewith some TS auditors' comment.

Auditor 1
From Customer Effect - you should rate it under 8 because loss the primary function of air condition even vehicle is operable ( but it against the 4th edition table ).

Auditor 2
From Customer Effect - you should rate it under 6 because loss of secondary function and vehicle is operable. Air Condition is only Secondary function for the vehicle. In other words, unless you are designing engine parts otherwise the failure only can reach as high 6 )

Auditor 3
ANYTHING ALSO POSSIBLE, it depends........ ( Seem like not answering at all ).

NOW, my question is.... when we are designing an System or Sub System or Component, do we look at the failure of its own or whether failure to the vehicle? If failure of its own, then it should be rated 8 as primary function is loss but if failure to the vehicle, then it should be rated 6 as it is considered as secondary function to the vehicle ( off course, except engine itself )..

What do you think as an expert? Please give your solid comment ( not again like.... it depends.... ).:bonk:
Can I conclude the FMEA 4th edition - Severity - Customer Effects, now analyse the part design failure as part of VEHICLE. Means, if the part causes the VEHICLE inoperable, then rated 8 and if the part only contribute comfort or convenience / secondary function TO THE VEHICLE (while VEHICLE still operating), it should be rated 5 or 6? This definition is totally different from FMEA 3rd Edition ( if you read carefully the definition for rank 5-8 ).

FMEA 3rd Edition mentioned - VEHICLE / ITEM INOPERABLE (8).. and VEHICLE / ITEM OPERABLE BUT COMFORT AND CONVENIENCE ITEMS INOPERABLE.. If we base on the FMEA 3rd Edition, RANK 8 include both VEHICLE and ITEM itself...( I hope you understand what am i trying to say ..) Means, now I can inform this GOOD NEWS for my customer that the severity that they determined last time (8) can be downgraded (6) as long as the VEHICLE is operable. AND, they can now drop the SPC since it is not SPECIAL CHARACTERISTIC anymore..
The rankings in the AIAG manual are explicitly described as "Suggested Evaluation Criteria," (my emphasis) and the manual makes it clear that "The team should agree on evaluation criteria and a ranking system and apply them consistently..." This means that unless your customer has explicitly required you to use the criteria and rankings given in the manual, you are free to devise your own, and should devise your own if you feel that the suggested criteria and rankings in the manual aren't appropriate.

All of this bickering about whether something is a 6 or an 8 doesn't add any value to anything. Determine the risks involved for everyone (the end user, your customer, your company) and take the appropriate steps to mitigate them. If your customer insists that a 6 should be an 8 and the difference requires more work on your part, they should be apprised of those costs at the RFQ stage.
 

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