[:es]nuevo AMFE o FMEA – VDA y AIAG: Seccion 6 : Optimizacion[:]

Cambios en las tablas AP

Esperamos que las tablas que puede ver arriba no sean las versiones finales que se encuentran en el manual. Mire de cerca y verá algunas incoherencias dentro y entre las tablas. Hemos realizado algunas modificaciones menores a partir de lo que apareció en el borrador del Manual. Por ejemplo, en la tabla AP para FMEA-MSR, hace referencia a las clasificaciones de gravedad de «6 a 4.» En todos los demás casos, las calificaciones cuando se muestran como un rango se enumeran como «4-6».

Pero, el propósito total de proporcionar este Manual preliminar es obtener comentarios como este. Se esperan pequeñas mejoras, pero el concepto de Prioridades de acción y el nuevo proceso de 6 pasos llegaron para quedarse.

1. Why was the change from RPN to AP made?
2. What is the «logic» behind the AP Logic Tables?

Why was the change from RPN to AP made?

• For many years, (some) quality professionals have pointed out that using the RPN to determine the priority of potential risks to tackle is a flawed approach.
• The RPN is determined by multiplying the “Security x Occurrence x Detection (or S x O x D)” rankings; this methodology sorts the potential 1,000 “problem descriptions” (10 x 10 x 10) into 120 groupings.
• The use of only 120 possible groupings with the corresponding limitation in discrimination can distort the importance of one potential risk relative to another.
• More importantly, when the RPN is used to determine a rank order of action plans, some “severe” potential risks (with a Severity ranking of 9 or 10) may not get attention that they should because associated low Occurrence and Detection rankings may drop the RPN below the actionable level. 
• The AP Tables of the new (draft) standard accommodate all 1,000 potential SxOxD results with one comprehensive table for each type of FMEA.  (Note: There are 3 different AP Logic Tables; one each for DFMEAs, PFMEAs and FMEA-MSRs.)

Changes to the AP Tables

We expect that the tables you can view above will not be the final versions that are in the handbook. Look closely and you will see some inconsistencies within and between the tables. We have made some minor modifications from what appeared in the draft Handbook. For example, on the AP table for FMEA-MSRs, it references Severity ratings of «6 to 4.» In all other cases the the ratings when shown as a range are listed as «4-6.»

But, the whole purpose of providing this draft Handbook is to get feedback like this. Minor improvements are to be expected, but the concept of Action Priorities and the new 6 step process are here to stay.

What is the «logic» behind the AP Logic Tables?

• The AP does not establish a “risk priority” but rather a priority level for action needed to reduce the risk of failure to function as intended.
• The rational used leads with the Severity rating since the severity of the effect of a failure rarely can be changed.
• All potential ratings of S, O and D combinations are assigned a High, Medium or Low Priority on the AP Table along with the justification (logic) for that priority level.
  • For “Priority High” action to improve prevention and/or detection controls (or justification on why current controls are adequate) MUST be taken.
  • For “Priority Medium” action to improve prevention and/or detection controls (or justification on why current controls are adequate) SHOULD be taken.
  • For “Priority Low” action to improve prevention and/or detection controls COULD be taken.
• The (draft) standard recommends that any Severity failure effect with 10 or 9 and a corresponding AP of High or Medium (and the action planned) be reviewed with management.

In summary…

Replacing the RPN with an AP evaluation effectively removes a logic issue (associated with the use of RPN) that allowed some potentially high priority risks to escape the attention they should be given.