Failure Effect Mode Analysis

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Failure Effect Mode Analysis
By Rajeev Kishore Uros
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Great question a confusion in estimation
How a raw egg bounce?
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Tacoma Bridge Collapse
Gondola FMEA
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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.

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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

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Do you know?

• Failure Modes... is a misnomer some
  sources now call FMEA by another name Fault
  Hazard Analysis.

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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

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Failures are not very well understood

No Publicly available data on failures on real
systems
WHY?
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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

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The Pre-work
Process or Prepared By ____________ Product Name _____ Page ________of ________ Person Responsible __________________ FMEA Date (Orig.) _______ Revised _______
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Guide to do FMEA
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FMEA Worksheet
Function Failure mode Failure effect S Failure Cause O Current Control D RPN Rec. Actions S O D RPN
1.
2.
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Terms and Definitions

• Fault
• Failure
• Function/Process
• Examples
• 1. Pencil Sharpener
• 2. Oil changing process

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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

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Def. Cont Failure Effect

• Immediate consequence of a failure
• Effects can range from very small to major
  disasters.
• Examples
• Improper writing
• Engine wear or Engine Failure

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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

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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

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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

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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

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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)

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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

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Pareto Diagram
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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

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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

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Link with continuous improvement
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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

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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

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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.

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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

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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

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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

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Resources

• http//www.pehwhk.com/Flyers/FAILURE20MODE20EFFE
  CT20ANALYSIS20_FMEA_.pdf
• http//www.fmeainfocentre.com/handbooks/fmeamanual
  .pdf
• http//www.fmeainfocentre.com/handbooks/umich.pdf.
  
• http//www.aluminiumville.co.uk/images/lightbox/al
  uminium_process.jpg
• www.nitrd.gov/subcommittee/hec/workshop/20060816/D
  ata/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/cor
  poration/fmea_training.pdf