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A Systematic Approach to Managing Risk Using DFSS and DFMEA

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  1. A Systematic Approach to Managing Risk Using DFSS and DFMEA Gary Deniston, CSQE, CRE, DFSS Black Belt Group Leader, Systems Design Quality Assurance / Reliability Engineering Covidien Energy-based Devices gary.deniston@covidien.com 303-530-6212

  2. Speaker Background • Speaker: • Gary Deniston is the Group Leader for the Systems Design Quality Assurance Team at Covidien Energy-based Devices. Gary has been involved with many aspects of systems engineering throughout his 20 plus year career, including application systems engineering, embedded systems software development, software quality assurance, reliability engineering and technical leadership in the medical device and industrial controls industries. Gary holds a BS degree in Computer Science from Regis University, and is a Certified Software Quality Engineer and Certified Reliability Engineer through the American Society of Quality. Gary is a DFSS Black Belt and Six Sigma leader within the Covidien organization.

  3. Covidien Imaging Products Contrast media and devices, radiopharmaceuticals Pharmaceuticals Branded and generic pharmaceuticals, acetaminophen, bulk narcotics and specialty chemicals Surgical Devices Endomechanical instruments and soft tissue repair products Respiratory and Monitoring Solutions Pulse oximeters, ventilators and airway management products Medical Supplies Nursing care, needles & syringes, monitoring, and operating room products. Vascular Therapies Vascular therapy and compression products Energy-based Devices Vessel sealing, electrosurgery and ablation products

  4. Presentation Objectives • Managing technical, safety and project risk is an essential element of successful new medical • device product development. DFMEA and key DFSS tools can be leveraged systematically to manage these risks. Information obtained from these tools can aid in project decision making and ultimately can lead to reducing time to market and development cost. This approach is applicable and scalable, from the simpler to the more complex development projects. An overview of this approach used to develop new medical devices will be presented, along with practical examples that can be utilized to continuously exceed our customer’s expectations for quality and reliability. • Some of the key topics in this presentation include: • How to Leverage Risk Management Tools and Techniques (DFMEA, Fault Trees, Hazard Analysis) • with other DFSS Tools (DOE, Tolerance Analysis) to Drive Predictable Product Quality and • Reliability Outcomes • How to Optimize the Utilization of Project Resources by Gathering and Analyzing the Right Data • Examples of this Approach in Action to Develop Safe and Effective Products on Time

  5. The Big Picture: Levels of Thinking Create the foundation for a network of pattern thinking that leads to the desired outcome Risk analysis and risk management system Structure Patterns Anticipate problems and deal with them before they occur. FMEA Events React to problems after they have occurred. Testing

  6. ISO 14971:2007 – Harmonized Standard for Risk Management • “… provides manufacturers with a framework within which experience, insight and judgment are applied systematically to manage risks associated with the use of medical devices.” “… a self-improving process through which the manufacturer must use knowledge gained post-production to improve and refine the safety of the device.” Compliance with this standard is rapidly becoming a general requirement of regulatory bodies worldwide.

  7. Safety Risk Analysis: Top Down Approach List of Harms ……. ……. ……. Fault Tree Hazard Analysis Occurrence “It is accepted that the concept of risk has two components: The probability of occurrence of harm; The consequences of that harm, that is, how severe it might be.” ISO 14971:2007 Introduction. Page v Severity

  8. FMEA Methods: Bottom Up Approach Prioritized List of Potential Failure Modes ……. ……. ……. Potential Product Safety Issues ……. ……. ……. PFMEA DFMEA System DFMEA AFMEA

  9. Risk Management: System Framework Risk Analysis Predictable Product Safety, Quality and Reliability Outcomes Develop Design Controls Design Requirements …… (IEC 60601-1) Perform Design Verification FMEA

  10. Risk Management: Project Decisions Information Risk Management Process Change Control Decisions Manufacturing Process Validation Decisions Field Failure Root Cause Analysis Decisions Concept Selection Decisions Material Selection Decisions Verification and Reliability Test Strategy Decisions DFSS Tool Deployment Decisions Regulatory Compliance Testing Strategy Decisions Resource Allocation Decisions Based on Prioritized List of Potential Failure Modes

  11. FMEA Worksheet 11 14 1 2 3 4 5 6 7 8 9 12 13 10

  12. FMEA Process Steps 6 1 11 ASSIGN SEVERITY DIVIDE SYSTEM INTO LOGICAL PARTITIONS CALCULATE THE RISK PRIORITY NUMBER RPN 7 2 12 IDENTIFY ROOT CAUSE CREATE A COMPONENT LIST FOR EACH PARTITION SORT FAILURE MODES IN RPN ORDER 8 3 13 IDENTIFY PRIMARY AND SECONDARY FUNCTIONS ASSIGN OCCURRENCE RECOMMEND AND TAKE ACTIONS ON THE HIGH RISK ITEMS DEPLOY DFSS TOOLS TO REMOVE ANY UNCERTAINTY 4 9 IDENTIFY CONTROLS AND MITIGATIONS IDENTIFY FAILURE MODES 14 RE-CALCULATE RPN 10 5 ASSIGN DETECTION DESCRIBE THE EFFECTS

  13. FMEA Process Step ~ Assign Severity 6

  14. FMEA Process Step ~ Assign Occurrence 8

  15. FMEA Process Step ~ Assign Detection 10

  16. FMEA Process Steps ~ Identify Controls ~ Assign Detection 9 10 • Detection is the likelihood of the controls in place detecting the failure mode. Score = 10: Control Does Not Exist or Failure Mode is not detectable Score = 1: The Design Control will Almost Certainly Detect The Failure Mode • Controls are the safeguarding measures in place at the time of review that are intended to do the following: • Eliminate the causes of failure • Identify or detect failure • Reduce impacts/consequences of failure

  17. ACME Coyote Lifter 11 12 1 2 3 4 9 10 13 5 7 8 14 6

  18. Two Level Three Factor DOE • This is a two level three factor experiment with four midpoints • Each part was tested until failure and the breakaway torque was recorded. • The Torque to Failure values are the responses.

  19. Pareto Analysis • Weld current, time, tip force, and the interactions between weld current and time, and weld current and tip force are the most significant factors.

  20. Interaction Plot Graphical Analysis • The plot indicates that an increase in weld current and time results in increased weld strength. The plot also indicates that a decrease in tip force results in increased weld strength. There is some interaction between the weld current and time and weld current and tip force.

  21. Main Effects Plot Graphical Analysis • By comparing the slopes of the lines on the plots, you can compare the relative magnitude of the factor effects. Again, the plot indicates that an increase weld current and time results in increased weld strength. The plot also indicates that a decrease in tip force results in increased weld strength.

  22. Determine the Optimal Design Parameters

  23. ACME Coyote Lifter 11 12 9 13 8 10 14

  24. Key Takeaway • Shifting our level of thinking from event level to structure level allows us to be more effective • Risk Management and DFSS tools can be leveraged systematically to manage risks. • Information obtained from these tools can aid in project decision making and ultimately can lead to reduced time to market and development cost. • For high RPN failure modes a DOE may be useful to identify the factors and interactions that have the highest impact on critical responses and to determine the optimal design parameters to reduce the likelihood of occurrence of a failure mode.

  25. Additional Information / Support Slides

  26. FMEA Process Steps ~ Logical Partitioning ~ Create a Component List 1 2 • Segment the System into Logical Partitions • Create a Component List • In an Application FMEA each user interaction may be considered a component • In the System FMEA each Functional Block may be considered a component • In the Design FMEA the structured BOM is an excellent source of a component list • In the process FMEA each process step can be considered a component

  27. FMEA Process Step ~ Identify the Functions 3 • From the component list develop a list of the component functions • A component may have multiple functions • Identifying component functions serves two purposes: • It sets the baseline for identifying the primary failure modes • It identifies components that are likely to have multiple failure modes

  28. FMEA Process Step ~ Identify the Failure Modes 4 • A potential failure mode is the manner in which a failure can occur or the ways in which it can fail to perform its intended function • Typical potential failure modes include the following: • Fail to open/close • Brittle • Cracked • Warped • Undersized/ Oversized • Open / Short • Corrupted

  29. FMEA Process Step ~ Describe the Effects 5 • Consider the effect on the end user of the product • Potential failure effects may include these examples: • System shuts down and becomes nonfunctional • Loss of control of system • Erratic system operation

  30. FMEA Process Step ~ Assign Severity 6

  31. FMEA Process Step ~ Indentify The Root Cause 7 • Potential failure causes identify the Root Cause of the failure mode and provide an indication of a design weakness that leads to the failure mode. • Failure Causes often include these types of problems: • Overstressing • Incorrect Material Specified • Improper Tolerance • Stability and Aging

  32. FMEA Process Step ~ Assign Occurrence 8

  33. FMEA Process Steps ~ Identify Controls ~ Assign Detection 9 10 • Detection is the likelihood of the controls in place detecting the failure mode. Score = 10: Control Does Not Exist or Failure Mode is not detectable Score = 1: The Design Control will Almost Certainly Detect The Failure Mode • Controls are the safeguarding measures in place at the time of review that are intended to do the following: • Eliminate the causes of failure • Identify or detect failure • Reduce impacts/consequences of failure

  34. FMEA Process Step ~ Assign Detection 10

  35. FMEA Process Step ~ Calculate RPN 11 • An RPN is a measurement of relative risk. It is calculated by multiplying together the severity, occurrence and detection ratings. The RPN is determined before implementing recommended actions and is intended to be used to prioritize the actions. • A policy for assigning corrective actions based on the value of the RPN should be agreed upon early in project planning.

  36. FMEA Process Steps ~ Sort Failure Modes by RPN~ Take Actions on High RPN~ Recalculate the RPN 12 13 14 • An RPN is a measurement of relative risk. It is calculated by multiplying together the severity, occurrence and detection ratings. The RPN is determined before implementing recommended actions and is intended to be used to prioritize the actions. • This process is iterated Continuously throughout a product’s life.

  37. Leveraging DFMEA with other DFSS Tools • The DFMEA recommended actions field may be used to identify opportunities for controls to be developed through the PFMEA. • DFSS tools often are useful in determining or validating assumptions made on the occurrence ranking • Tolerance Analysis • Monte Carlo Simulations or Circuit Simulations • Reliability Testing • For high RPN failure modes a screening DOE may be useful to identify the factors and interactions that have the highest impact on critical responses.

  38. Maximize Benefits of Reuse • By using a modular approach to DFMEA the benefits of reuse can be maximized. If the design is modularized into logical partitions, the data and information can be managed so that it is easily reused on future projects. • The modularity approach will encourage reuse of this information on future designs. These logical partitions or modules can be viewed as building blocks. Building a framework that allows these blocks to easily be linked leads to increased efficiency on each subsequent project that reuses modules from the preceding project.

  39. References McDermott RE, Mikulak RJ, Beauregard MR. 1996. Dailey KW. 2004. Failure Modes and Effects Analysis during Design of Computer Software 0-7803-8215-3/04/$17.00 2004 IEEE FMEA Is Not Enough 1-4244-2509-9/09/$20.00 IEEE Using Failure Mode Effect Analysis to Increase Electronic Systems Reliability 1-4244-1218-8/07/$25.00 IEEE