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    Fmea Fmea Presentation Transcript

    • FAILURE MODES AND EFFECTS ANALYSIS (FMEA) Julie VanLaanen
    • Failure Modes and Effects Analysis (FMEA)
      • Failure Mode and Effect Analysis is an analytical technique used by a product design team as a means to identify, define, and eliminate, to the extent possible, known or potential failure modes of a product or system.
    • How The FMEA Fits Into Your Final Proposal Proposal Sections: Letter of Intent ----------------->> Transmittal Title Page Executive Summary Table of Contents List of Figures Letter of Intent ------------------>> Introduction QFD/House of Quality ------>> Design Objectives FMEA Analysis ----------------->> Product, System, or Process Division of Responsibility Project Milestones------------- >> Project Schedule Budget Resume -------------------------->> Qualifications Bibliography QFD/House of Quality ------>> Appendices Detailed Project Schedule- >> Appendix Glossary
    • Was Failure a design requirement in your QFD? Should it have been? Can you design for failure?
    • Failure is ALWAYS a Design Constraint
      • All Products fail!
      • Determining how they fail, when they will fail, and why they are failing will allow a designer to incorporate failure as an acceptable design constraint.
      • Failure as an acceptable design constraint = Customer Satisfaction = Design Quality
    • From: “Inviting Disaster – Lessons From the Edge of Technology” By James R. Chiles
      • Regarding the continuing failure of rear cargo door on a DC-10 :
      • “ The design was originally going to use hydraulics, but under pressure from its client, American Airlines, to simplify and lighten the DC-10 equipment; McDonnell Douglas shifted to an electric door closer instead. This worried engineers working for the builder of the door assembly, Convair Division of General Dynamics. Convair engineers even sent McDonnell Douglas a formal document, called a “ failure modes effects analysis ,” describing the problem and the disastrous consequences.
    • How could your design fail?
      • Identify potential failure areas in your design
      • Determined analytically through models and analysis
      • Determined empirically through stressed life testing
      • Determined after product release through customer warranties and failure reporting
    • When will my design fail?
      • Determining how my design might fail requires a through understanding of my design.
      • Part of answering this question is determining when my customer believes failure is acceptable.
    • When will my design fail?
      • Design failure is acceptable if customers perceive it as acceptable. Design Failure has a direct effect on Customer perceptions of Product Quality.
      • Periodic Maintenance (oil changes)
      • Periodic Replacements (change tires)
      • Acceptable End of Life (customer expectations – car replacement every 8-10 years)
    • Reliability Curve Assuming a part/product is designed correctly, statistically it should follow a standard bath-tub curve Infant Mortality – failures don’t usually affect the customer, except DOA Useful life – failures here are problems Wear Out – failures here are acceptable
    • Causes of Reliability Curve Failure
    • Tools used to Design for acceptable Product Failure
      • Failure Modes and Effects Analysis (FMEA): Method to identify and understand potential product failures and their severity
      • Mean Time Between Failures (MTBF) of individual parts. Determined by:
        • MIL Standards
        • Testing
        • Mathematical Predictions
      • Design of Experiments (DOE): Experimentally optimizing our design using physical models and optimized testing (Taguchi)
    • Tools to used to Design for acceptable Product Failure (cont.)
      • Statistical Process Control (SPC): Monitoring process failures through tight statistical control of process variables
      • Six-Sigma (6  ): Statistical repeatability to six standard deviations (in other words, 99.9999998% within design specifications!)
    • QUALITY MAP
    • Failure Modes and Effects Analysis (FMEA)
      • Begins at the initiation of a product design cycle
      • Seeks to identify potential failure modes before a actual failure occurs
      • Continues throughout product design cycle
    • Three Key Questions Posed by FMEA
      • What could fail in each component of my product?
      • To what extent might it fail and what are the potential hazards produced by the failure?
      • What steps should be implemented to prevent failures?
    • Design FMEA Analysis  = Critical characteristic which may effect safety, compliance with Gov. regulations, or require special controls. SEV = Severity rating (1 to 10) OCC = Occurrence frequency (1 to 10) DET = Detection Rating (1 to 10) RPN = Risk Priority Number (1 to 1000)
    • Rifle Bolt Example D E T Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Item and Function
      • List each subassembly and component, along with it’s basic function. Example: Rifle Bolt
      D E T
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Identify and List Potential Failure Modes
      • For any failure mode, the idea is to identify what could occur, not that it will necessarily occur. Identify through:
      • Brainstorming
      • Analysis
      • Test
      • Experience
    • Example Failure Modes
    • Identify and List Potential Failure Modes Jamming Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • List Potential Effects from Failure
      • Impact on Environment
      • Hazard to humans
      • Excessive noise
      • Poor Appearance
      • Unpleasant Odor
      • Erratic Operation
    • Potential Effects from Failure Failure of weapon to function Jamming Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Critical Potential Effects from Failure
      • Are the potential effects critical? Will they effect:
        • Personal Safety
        • Compliance with a Government Standard
        • Compliance with a Government Regulation
        • Require special controls
    • Identifying Critical Failures Failure of weapon to function Jamming Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Specifying Severity of Failure (SEV)
      • Estimate potential severity (SEV) of failure and its effect
    • Specifying Severity of Failure (SEV) 8 Failure of weapon to function Jamming 10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Potential Cause of Failure
      • List possible potential causes of failure
        • Tolerance stack-up
        • Assembly errors
        • Poor maintenance
        • Impact loading
        • Overstressing
        • Poor Design
      • These causes should indicate appropriate preventive measures that might be adopted
    • Potential Cause of Failure
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Likelihood of Occurrence (OCC)
      • Estimate the potential occurrence of failure
    • Likelihood of Occurrence (OCC) 5
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming 6
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Detection Methods & Quality Controls
      • Develop Methods to detect and control the potential causes of failure
        • Manufacturing tests
        • Incoming Inspection
        • SPC Methods
        • Vendor/Supply Controls
        • Dimension Inspection
    • Detection Methods & Quality Controls
      • Measure patterns
      • Confirm finished casting dimensions
      5
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming
      • Incoming Part Inspection
      • Dye penetrant testing
      6
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Likelihood of Detection (DET)
      • Estimate the likelihood that the detection method in place will actually detect the fault
    • Likelihood of Detection (DET) 3 5 D E T
      • Measure patterns
      • Confirm finished casting dimensions
      5
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming
      • Incoming Part Inspection
      • Dye penetrant testing
      6
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Calculate a Risk Priority Number (RPN)
      • The RPN prioritizes the relative importance of each failure mode and effect on a scale of 1 – 1000. It is calculated as follows:
      • RPN = (SEV) x (OCC) x (DET)
      • A 1000 rating implies a certain failure that is hazardous and harmful
      • A 1 rating is a failure that is highly unlikely and unimportant
      • Ratings above 100 will occur
      • Rating below 30 are reasonable for typical applications
    • Calculate a Risk Priority Number (RPN) 3 5 D E T 1 2 0
      • Measure patterns
      • Confirm finished casting dimensions
      5
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming 300
      • Incoming Part Inspection
      • Dye penetrant testing
      6
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Develop Recommended Actions
      • Based on your RPN number, develop recommended actions to solve failure modes
        • Assign responsibilities
        • Outline corrective actions
        • Revise test plans, material specifications
      • These actions should be specific, not general action items
    • Develop Recommended Actions 3 5 D E T Initiate SPC program to check and maintain bolt dimensions 1 2 0
      • Measure patterns
      • Confirm finished casting dimensions
      5
      • Out of spec. Dimension
      • Change in shell refractory
      8 Failure of weapon to function Jamming Initiate radiographic testing of all rifle bolts 300
      • Incoming Part Inspection
      • Dye penetrant testing
      6
      • Shrinkage
      • Porosity caused by improper feed
      10 Catastrophic failure with destruction of weapon and injury to personnel Fracture
      • Rifle Bolt
      • Chambers bullet
      • Locks into receiver
      • Fires Round
      • Sustains firing pressure on lugs
      • Provides extraction of spent case
      Recommended Actions R P N Detection Method & Quality Controls O C C Potential Cause(s) of Failure S E V Potential Effects of Failure Potential Failure Mode Part and Function
    • Acknowledgement
      • Lecture taken from:
      • Dr. Bob Frost of the Metallurgical Engineering Dept. from his course on Statistical Process Control (SPC)
      • Dr. Munoz from the Mechanical Engineering Department.
      • Product Design: Techniques in Reverse Engineering and New Product Development by Kevin Otto & Kristin Wood, pp 564-571 .