Hi Bev D,
I have a slightly different perception of Severity rankings. In your paper you have the following:
Recommendations:
Severity Scales: Keep it simple
Create a simple scale that everyone uses. Experience has shown that a 1-5 scale is usually sufficient. 1-3 scales can be perceived as lacking in resolution and often leads to distress as teams struggle with large categories. 1-10 scales tend to have too fine a resolution and teams struggle with the small differences. 1-5 seems to be ‘just right’.
I have facilitated hundreds and hundreds of D & P
FMEA’s, and never have I had a problem with a FMEA Team not comprehending nor constructing a 1 – 10 ranking method for their industry or service organization. In rare cases, some industries desire more resolution. The simplification of categories comes by defining regions on the S x O, Criticality Matrix.
On the Criticality Matrix as little as 3 categories/classifications, to a more appropriate selection of 5 categories/classifications can be defined. Industries, customers, or companies can define the definition/selection of the S x O intersections as part of the FMEA pre-work. It is these definitions which lead to the categories of:
“5) Critical”,
“4) Critical with Failure eliminated through preventive control” (if desired),
“3) Significant”,
“2) Annoyance” (if desired), and
“1) Characteristics with Appropriate Actions / Controls Already in Place”.
“5) Critical”, “3) Significant”, and “2) Annoyance (if defined)” Classifications always require Recommended Actions.
The “4) Critical with Failure eliminated through preventive control” Classification requires a special Recommended Action note, such as, “None at this time based on low Occurrence and Detection rankings.” or “Based upon historic data, no action is required at this time.” Have your company’s lawyer(s) to advise your company and teams for specific language.
The “1) Characteristics with Appropriate Actions / Controls Already in Place” Classification should have the Recommended Action of “None” as suggested in the AIAG FMEA Reference Manual.
The Criticality Matrix, a pre-FMEA planning activity, takes all of the guess-work out of defining Product/Process Characteristics and one dimension of when and type of Recommended Actions are required. Other pre-FMEA planning activities make FMEA development quite an easy task after a company or team creates them. These become business game changing strategies.