RPN numbers in FMEA - It is not correct to go only by the RPN numbers when doing FMEA

A

Arvind

#11
Judging Risk priority number RPN by absolute value can be misleading

Risk priority number RPN is calculated as a product of a) Severity b) Occurance and c) Detection. Each values being max 10, RPN is maximum 1000.
One of the commonly made mistake is that many people become complacent by absolute value of RPN. That can be misleading. This is particularly true if RPN # is low but customer has concerns.
What is essential is to take a look at relative magnitudes of RPN to prioritize improvement actions.
It is helpful to generate pareto of top RPN # and compare with customer concerns to decide business case for asking resources for working on improvement projects.

Arvind
 
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B

Bill Ryan - 2007

#12
There are different views on how to prioritize a "To Do" list from a PFMEA excersize. One (probably most common) is to go strictly by the Risk Priority Number. IMO - this is used by companies that view the PFMEA as a "necessary evil" (satisfy a customer requirement). Another fairly common means is to use S x O and then pareto those results. In my mind, there is no standard "formula" to address what a company should or shouldn't be directing their improvement efforts toward with regard to the ranking indices on the PFMEA. Severities of 9 & 10 definately need to be worked on to have the lowest possible chance to either: a) be produced; or b) be shipped. Normally I look at Severities of 6-8 as "Warranty" issues for my customer and don't wish to ship those either as they tend to get you placed on Contained Shipping ($$$$). The remaining Severities are, in my experience, the "low hanging fruit" which more or less are irritations to the customer and usually need the most "risk vs. cost" attention.

As always - this is JMHO.
 

Jim Wynne

Staff member
Admin
#13
What we need to remember is that the FMEA document is not the FMEA--it's only a record of it. FMEA is the process of assessing and mitigating risk. Risk comes in many flavors, and exists in the eye of the beholder (normally the customer). The primary risk in any process in business is fiscal. It's not "If this goes wrong, the product will blow up and someone will be injured," it's "If this blows up and someone is injured, it's gonna cost us." Call me cynical, but the bottom line on the P&L statement is king. So in in answer to your question, yes, cost should always be considered.
 
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