21. Action Results:

After the corrective action taken, the team leader is to verify the action for implementation. Estimate and record the resulting ‘Severity’ (S), ‘Occurrence’ (O) and ‘Detection’ (D) rankings. Calculate the “Resulting RPN”. If no actions are taken, leave the related ranking columns blank.

All resulting RPN’s should be reviewed and if further action is considered necessary, repeat Step-22 to Step-23. The controls should be written against each causes listed in potential causes column. If no control on the causes then write “No Control”.

Determining Action Priorities:

• Once the team has completed the initial identification of failure modes and effects, causes and controls, including rankings for severity, occurrence and detection, they must decide if further efforts are needed to reduce the risk. Due to the inherent limitations on resources, time, technology, and other factors, they must choose how to best prioritize these efforts.
• The initial focus of the team should be oriented towards failure modes with Highest Severity Rankings. When the Severity is 9 or 10, it’s imperative that the team must ensure that the risk is addresses through existing design controls or recommended actions (as documented in the FMEA).
• For failure modes with Severities 8 or below the team should consider causes having highest occurrence or detection rankings. Its team’s responsibility to look at the information identified, decide upon an approach, and determine how to best prioritize the risk reduction efforts that best serve their organization and customers.

21. Risk Priority Number (RPN):

Risk Priority Number is Severity (>S) multiplies by Occurrence (O) and Detection (<D).

Thus, Risk Priority Number (RPN) = (>S) x (O) x (<D).

The RPN value will be lies in between 1 to 1000. For higher RPN’s, the team must undertake efforts to reduce the risks through corrective action(s). In general, regardless of the resultant RPN, special attention should be given when the severity of the potential failure effect is high.

Say for example, if the RPN target value is equal or goes beyond 100 (i.e. ≥ 100) then corrective actions are planned to reduce the risks based on RPN values. Recommended actions are planned and FMEA will be updated and revised accordingly. Re-ranking will be done in action results and re-RPN Value will be calculated and hence RPN will be reduced. If in case customer gives the target for RPN value, then the same will be adopted.

Also based on severity the below RPN target is used for FMEA revisions unless otherwise specified by the customer.

(Note: RPN for Severity = 8 or 9 can be adapted to the customer requirements (for instance, raised to 50 if customer requires only this and not 36).

22. Recommended Action(s):

After completion of the steps described above, the RPN’s are to be analysed in the form of pareto-charts to identify the priority areas for control.

Higher risk priority numbers generally requires immediate action, however, the severity ranking more than 8 are to be considered with high priority irrespective of the RPN value.

The following actions should be considered:

• To reduce the probability of occurrence, revisions in process controls are required.
• The actions recommended should be to prevent/eliminate the causes to reduce the occurrence ranking. The prevention techniques such as mistake proofing methodology, SPC methods and continuous improvement are to be considered.
• The intent of any recommended action is to reduce rankings in the following order: Severity, Occurrence, and Detection.
• Only a process revision can bring about a reduction in the severity ranking.
• Generally improving detection control is costly and ineffective for quality improvement.
• Increasing quality control inspection frequency is not a positive corrective action and should only be utilized as a temporary measure.
• Emphasis must be on preventing/reducing occurrence of a defect rather than detecting them.
• Recommend change to current control systems such as introduction of statistical process control and process improvements rather than random quality checks or inspection.
• If no action is recommended for a specific cause indicates by entering “NONE” in this column.

Here are few of approaches to reduce these are explained below:

• To reduce Severity (S) ranking: Only a design or process revision can bring about a reduction in the severity ranking.
• To reduce Occurrence (O) ranking: To reduce occurrence, process and design revisions may be required. A reduction in the occurrence ranking can be effected by removing or controlling one or more of the causes of the failure mode through a product or process design revision.
• To reduce Detection (D) ranking: The preferred method is the use of error/mistake proofing. A redesign of the detection methodology may result in a reduction of the detection ranking.

23. FMEA Management (FMEA Review and Updation):

• This document is a living document and should always reflect the latest revision level. This is to be reviewed whenever there is a change in process, modifications in controls, on identification of new failures and causes, when the process becomes unstable and/or incapable.
• Whenever FMEA is reviewed the concerned process related documents like control plans, operating instructions, setup instructions, maintenance work instructions, etc., are to be reviewed and updated if required.
• When the process is out of control or the product is failure, FMEA CFT should evaluate FMEA again, ensure whether existing control measure can poses all the failure or not and definitude resolving.
• Review and update the FMEA during each milestone of NPD.
• When any 4M Change, FMEA should be reviewed and approved.
• When any customer claims / warranty claims, exceptional in-house rejection & quality catastrophe.
• Once in 6 months if any of the above not happened.