Failure Effect Mode
Analysis
By
Rajeev
Kishore
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 upfront 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
Product Name _____
Prepared By ____________
Page ________of ________
Person Responsible
__________________
FMEA Date (Orig.) _______ Revised _______
Guide to do FMEA
STEP 1
STEP 2
• Scope Project
STEP 3
• Identify potential effects of failures
STEP 4
• Determine severity rankings
STEP 5
• Identify causes of failures
STEP 6
• Determine occurrence rankings
STEP 7
• Define current control methods
STEP 8
• Determine detection rankings
STEP 9
• Calculate Risk Priority Numbers
STEP 10
• Prioritize corrective actions
• Brainstorm all potential failures
FMEA Worksheet
Funct Failure Failure S Failure O Current D R Rec.
ion
mode
effect
Cause
Control
P Actions
N
1.
2.
S O D R
P
N
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 graphite
2. 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 writing
2. 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
Component
Proving
Process
Mistake
Proofing
Techniques
Continuous
Improvement
Programs
FMEA
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
Resources
http://www.pehwhk.com/Flyers/FAILURE%20MODE%20EFFECT%20
ANALYSIS%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.jp
g
www.nitrd.gov/subcommittee/hec/workshop/20060816/Data/HECIWGFSIO-2006-Data-Failure-Schroeder.pdf
http://www.npd-solutions.com/fmea.html
http://www.sigmazone.com/gondola_lift_fmea.htm
http://www.suppliermanageronline.com/training/corporation/fmea_training.pdf