RPN, Risk Priority Number, Severity, Occurrence, Detection In FMEA

Severity :
It is the effect of a failure.
Consider how serious effect of the failure mode.
Rank is assigned to seriousness of the failure mode from 1 to 10 ( 10 is very severe /dangerous and 1 is no effect.

Occurrence :
It is the likelihood of occurrence of the failure during production.
Rank is given to occurrence from 1 to 10. (10 is very high occurrence and 1 is almost zero.

Detection :
It is the rank indicating the control in the process to detect the failure.
Rank is given to control mechanism from 1 to 10 (10 is No control and 1 is almost not possible to create the defect.
1 is given when Pokayoke type control is implemented where defect is completely eliminated.

SOD/ RPN :
It is the outcome of multiplication of Severity,Occurrence &Detection.
RPN= Severity x Occurrence x detection. 

High RPN no. Indicates high risk Low RPN no. Indicates Low risk.

For high RPN, Based on the RPN No. Action plan is planned, implemented & RPN no. is reduced.

Also Read

5'S., Bench-marking., Calibration, CAPA., Fishbone Diagram, FMEA., Good Habits for Successful Engineers, Kaizen., Kanban., LEAN., MSA, OEE, 

PDCA, PPAP, QA/QC , Quality,  Six Sigma., 

Priority Matrix,   Quality Improvement , Quality Problem , Reproducibility, Root Cause Analysis., Scatter Plot., Seven QC Tools., Statistical Quality Control, SWOT Analysis, The key to success