Failure Effect Mode Analysis

ByRajeevKishore

Uros

Great question; a confusion in estimation

How a raw egg bounce?

Tacoma Bridge Collapse

Gondola FMEA

Introduction to FMEA• To introduce new products or

manufacturing processes successfully in a cost-effective manner, resources should be allocated up-front to prevent problems.

• Fixing the problem after a product is manufactured is more expensive than it is to prevent them.

Benefits of FMEA• Reduce the number of engineering changes• Reduce product development time• Lower start-up cost, and reduces warranty• Greater customer satisfaction• Increased cooperation and teamwork

between various functions• A well-documented project history and

information database

Do you know?

“Failure Modes...” is a misnomer — some sources now call FMEA by another name: “Fault Hazard Analysis.”

Reliability• Failures are expensive• System flakiness is a major source of user

frustration- 25% in survey have seen peers kicking their computers

- 2% claim to have hit the person next to them in their frustration

Failures are not very well understood

No Publicly available data on failures on real

systems

WHY?

Different types of FMEA• Design (DFMEA): technique used

primarily by a Design Responsible Engineer/Team as a means to assure potential failure modes, causes and effects have been addressed for design related characteristics

• Process (PFMEA): technique used primarily by a Manufacturing Engineer/Team as a means to assure potential failure modes, causes and effects have been addressed for process related characteristics

The Pre-work

Process or Prepared By ____________Product Name _____ Page ________of ________Person Responsible __________________ FMEA Date (Orig.) _______ Revised _______

Guide to do FMEA

FMEA Worksheet

Function

Failure mode

Failure effect

S Failure Cause

O Current Control

D RPN

Rec. Actions

S O D RPN

1.

2.

Terms and Definitions• Fault• Failure• Function/Process• Examples –

1. Pencil Sharpener 2. Oil changing process

Def. Cont…

Failure Mode• The way failure occurs• Can cause a failure mode in another

item• Identify and list possible failure modes• Examples –

1. Frequently breaking the graphite2. Wrong type of oil or No oil added

Def. Cont…

Failure Effect• Immediate consequence of a

failure• Effects can range from very small

to major disasters.• Examples –

1. Improper writing2. Engine wear or Engine Failure

Def. Cont…

Severity (SEV)• Worst consequence of a failure• How is it determined?• Standard scale from 1 (no danger)

to 10 (very severe)• Prioritize the failures modes and

their effects

Def. Cont…

Failure Cause• Design weakness - How the failure

could occur?• Listed in technical terms and are

documented• Examples –

1. Improper mixture of Graphite and Clay 2. Misread oil chart or Hurrying

Def. Cont…

Occurrence (O)• Probability of the cause occurring• Look for similar products or

processes• Probability number scale from 1

(not likely) to 10 (inevitable)• Detailed development section of

FMEA Process

Def. Cont…

Current Controls• Current controls that prevent the

failure cause (before causing effects)

• Examples – 1. improve quality of graphite 2. No control or engine light

Def. Cont…

Detection (D)• Assessment of the likelihood that

the current controls will detect failure cause or failure, before it reaches the customer.

• Different techniques are used by an engineer

• Identify the detection number ‘D’, ranging from 1 (easily detectable) to 10 (cannot detect)

Def. Cont…

Risk Priority No (RPN)• RPN = S * O * D

• Risk that has greatest concern can be identified

• Failures are prioritized according to:- Severity- Occurrence - Detection

• Requires additional planning or action

Pareto Diagram

Recommended Actions and Results

• Address potential failures that have a high RPN

• Are any further actions required?• Assign new value for S, O and D,

and calculate new RPN value• Update the FMEA as the design or

process changes

Development Team• Crucial step in FMEA • FMEA is a team function

- Formulate cross functional team

- Understand customer requirements – both internal and external inputs- All team members walk and observe the process- Make notes or observations

Link with continuous improvement

FMEA Timing • FMEA should be updated

whenever:- At the conceptual stage - Changes are made in the design - New regulations are instituted- Customer feedback indicates a problem

Uses of FMEA• Development of methods to design• Test systems to ensure that the

failures are eliminated• Tracking and managing potential

risks• Ensuring that failure will not injure

customer or impact a system• Evaluation of customer reviews on

the problems indicated

TQM Principles•Continuous Improvement Process

•Continued building and prevention of failure on the process

•Employee Involvement and Empowerment

•Employees can feel empowered and involved if they correct an error in a process or part.

•Leadership

•There needs to be a team leader for every group, which is assigned to one part of the process.

TQM Principles•Performance Measurement

•RPN, lower the better

•Supplier Partnership

•If one supplier has bad parts, it directly affects your products, by creating failure in your company.

•End Customer Satisfaction

•Reliability meets customer requirements

Limitations• FMEA is limited by the team

experience• FMEA may only identify and avoid

major failure modes• Multiplication of rankings may

result in rank reversals

FMEA Conclusion• Purpose of FMEA, is the process of

identifying potential failure modes and their associated causes, assigning severity, Occurrence, and Detection ratings, and calculating RPN

• RPNs should be used for continuous improvement activities

Resourceshttp://www.pehwhk.com/Flyers/FAILURE%20MODE%20EFFECT

%20ANALYSIS%20_FMEA_.pdf

http://www.fmeainfocentre.com/handbooks/fmeamanual.pdf

http://www.fmeainfocentre.com/handbooks/umich.pdf.

http://www.aluminiumville.co.uk/images/lightbox/aluminium_process.jpg

www.nitrd.gov/subcommittee/hec/workshop/20060816/Data/HECIWG-FSIO-2006-Data-Failure-Schroeder.pdf

http://www.npd-solutions.com/fmea.html

http://www.sigmazone.com/gondola_lift_fmea.htm

http://www.suppliermanager-online.com/training/corporation/fmea_training.pdf