When the failure modes have been ranked by their RPN, corrective actions should be first directed at the highest ranked concerns and critical items identified.
The intent of any recommended action is to reduce one or more (or all) of the occurrence, severity and/or detection rankings.
Only a design revision can bring about a reduction in the severity ranking. If no actions are recommended for a specific cause, this should be indicated.
A reduction in the occurrence ranking can only be effected by removing or controlling one or more of the causes of the failure mode through a design revision.
An increase in design verification actions will result in a reduction in the detection ranking ONLY.
Design FMEA doesn�t rely on process controls to overcome potential weaknesses in the design; however, it does take technical and physical limitations of a process into consideration (Design Rules)