FAILURE FAILURE MODE MODE

EFFECTIVE EFFECTIVE ANALYSISANALYSIS

IntroductionIntroduction Failure Mode Effect Analysis is an analytical Failure Mode Effect Analysis is an analytical

technique that goes in for combining Technology and technique that goes in for combining Technology and Experience of people to identify foreseen failures in a Experience of people to identify foreseen failures in a product or process and planning to eliminate the product or process and planning to eliminate the Failure. Failure.

DefinitionDefinition

FMEA is a group of activities to understand FMEA is a group of activities to understand and evaluate potential failure of product or and evaluate potential failure of product or process and its effects, and identify actions process and its effects, and identify actions that eliminate or reduce the potential failures.that eliminate or reduce the potential failures.

Types of FMEATypes of FMEA

Major ClassificationMajor ClassificationDesign FMEADesign FMEAProcess FMEAProcess FMEA Sub ClassificationSub ClassificationEquipment FMEAEquipment FMEAMaintenance FMEAMaintenance FMEAService FMEAService FMEASystem FMEASystem FMEA

DESIGN FMEADESIGN FMEA

Design FMEA use in the design Design FMEA use in the design process by identifying known process by identifying known and foreseeable failures modes and foreseeable failures modes and ranking failures according to and ranking failures according to their impact on the producttheir impact on the product. .

PROCESS FMEAPROCESS FMEA

It is used to identify potential process It is used to identify potential process failure modes by ranking failures and failure modes by ranking failures and establishing priorities, and its impact establishing priorities, and its impact on the Internal or external customers.on the Internal or external customers.

RELIABILITYRELIABILITYReliability is defined as the probability that Reliability is defined as the probability that

the product will perform as per the the product will perform as per the expectation for a certain period of time, expectation for a certain period of time, under the given operating conditions, and under the given operating conditions, and the given set of product performance the given set of product performance characteristics.characteristics.

The part, assembly, or process under The part, assembly, or process under consideration, the reliability of each sub consideration, the reliability of each sub system and factors that contribute to failure system and factors that contribute to failure to be found. to be found.

FAILURE RATEFAILURE RATEProducts follow a pattern of failure.Products follow a pattern of failure.There is no information about the reliability (i.e. There is no information about the reliability (i.e.

Failure) of the product.Failure) of the product.Failure Rate is a constant is known period of Failure Rate is a constant is known period of

failure can be found out using Exponential failure can be found out using Exponential DistributionDistribution

RRt = e t = e – – λλt t RRtt = Reliability of survival = Reliability of survival

RRt = e t = e - - t / t / θθ t t = = Time for operation without failureTime for operation without failure

λλ = Failure rate = Failure rate θθ = Mean time to = Mean time to FailureFailure

PROBLEMPROBLEM

Failure Rate Failure Rate λλ = .0002 per hour = .0002 per hour What is the probability that it will survive What is the probability that it will survive

or reliable during the first 200 hours of or reliable during the first 200 hours of operations?operations?

SolutionSolution

Rt = e – Rt = e – λλtt

= e – (200) (0.0002) = e – (200) (0.0002)

= 96.08 = 96.08 %%