What is Severity, Occurence and Detection?

What is Severity, Occurrence and Detection in FMEA?

 - Severity, occurrence and Detection is a part of Failure Mode and Effect Analysis.

Severity rating in FMEA

 - Severity ratings based on criticality of the risk. 

 - It evaluate the impact of the failure mode.

 - Severity rating ranging from 1 to 10, in which 1 means severity is extreme low and 10 means high severity leading to hazard without intimation or warning.

 - In some industries, categories are given instead of numerical values

Minor - This includes rating 1 of severity which is very minor issues and ignored by customer.

Low - This includes 2 and 3 rating and may cause slight discomfort for customer due to minor issue with performance.

Moderate - This includes 4 to 6 ratings and cause dissatisfaction to customer due to performance degradation.

High - This includes 7 and 8 rating and cause high impact on customer due to significant impact on performance.

Very High - This includes 9 and 10 rating which cause accidents, violate govt regulations, fighting with safety of workers and equipment.

Download  Severity Table

 Occurrence rating in FMEA

 - Occurrence is the incident or frequency of something happening.

 - It evaluate the chances of failure happening.

 - Occurrence rating ranging from 1 to 10, in which 1 is lowest occurrence and 10 is highest occurrence.

 - In some industries, categories are given instead of numerical values

Minor - This includes rating 1 of occurrence means failure is unlikely to happen.

Very Low - This includes rating 2 and occurrence is very low.

Low - This includes rating 3 and 4, Isolated incidents (incident that are separate from other incidents) are expected.

Moderate - This includes rating 5 to 7 and failures occur sometimes.

High - This includes rating 8 and 9, failure occur often in process.

Very High - this includes rating 10 and failure is happen every time in process.

Download Occurrence Table

Detection rating in FMEA

 - Detection means potential failure will be caught or detected before reaching to customer.

 - Detection rating ranging from 1 to 10 and it is opposite to severity and occurrence. Rating 1 means highest chance of detection and rating 10 means lowest chance of detection.

 - In some industries, categories are given instead of numerical values

 Very High - This includes rating 1 and 2 and shows existing system having strong possibility to detect failures.

High - This includes rating 3 and 4 and shows existing system having strong possibility to detect failures before reaching to customer.

Moderate - This includes rating 5 and 6 and shows existing system might detect the failure.

Low - This includes rating 7 and 8 and shows less chance of detection of failure.

very Low - This includes rating 9 and shows failure is happen and existing system not register the presence of failure.

No Chance - This includes rating 10 and shows failures will happen and existing system not able to detect its presence.

Download Detection Table

Risk Priority Number (RPN)

 - RPN is a Risk Priority Number

 - It is multiplication of Severity, Occurrence and Detection.

 - RPN is higher then potential risk is also higher.

 - RPN gives us better tool to focused on improvement efforts.

 - RPN ranges from 1 (Best) to 1000 (Worst).