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Root cause analysis common problems and solutions

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The process of diagnosing product problems identified during design, manufacture or use brings many challenges. The presentation will discuss ways to alleviate these difficulties using a structured, …

The process of diagnosing product problems identified during design, manufacture or use brings many challenges. The presentation will discuss ways to alleviate these difficulties using a structured, troubleshooting-based approach, and being aware of some common errors and ways of dealing with them.
• How to analyze data for low frequency failures
• Using the information from RCA for improving both prevention and detection
• Understand why finding a product solution often isn’t enough

Published in: Technology, Business

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  • 1. Root Cause Analysis:  Root Cause Analysis: Common Problems  Common Problems and Solutions Duke Okes ©2012 ASQ & Presentation Duke Presented live on Aug 09th, 2012http://reliabilitycalendar.org/The_Reliability_Calendar/Webinars_liability Calendar/Webinars ‐_English/Webinars_‐_English.html
  • 2. ASQ Reliability Division  ASQ Reliability Division English Webinar Series English Webinar Series One of the monthly webinars  One of the monthly webinars on topics of interest to  reliability engineers. To view recorded webinar (available to ASQ Reliability  Division members only) visit asq.org/reliability ) / To sign up for the free and available to anyone live  webinars visit reliabilitycalendar.org and select English  Webinars to find links to register for upcoming eventshttp://reliabilitycalendar.org/The_Reliability_Calendar/Webinars_liability Calendar/Webinars ‐_English/Webinars_‐_English.html
  • 3. by Duke Okes© 2011 Duke Okes
  • 4. Some Typical Problems with RCA Not really getting to the root cause Don’t consider past (each problem as unique) Mental M t l vs. visual analysis i l l i Focus on technical knowledge vs. thinking p g g process©2011 Duke Okes
  • 5. Reliability Applications for RCA Design Produce Distribute & Use Failures during the design process Production/delivery equipment failures Field failures©2011 Duke Okes
  • 6. Confusion over P bl Problem S l i T i l Solving Terminology Proactive actions Preventive action is taken to reduce the likelihood of occurrence of a problem; can be independent of or part of corrective action Reactive actions Correction Containment puts a barrier around suspect/defective items so they won’t get used Remedial action corrects the problem symptoms by reworking, repairing or replacing the defective items p g p g Corrective action addresses the causes to prevent recurrence Physical (direct) cause that created the problem System (latent) cause that created the physical cause©2011 Duke Okes
  • 7. Types of Causes Physical Item that caused failure Ph i l – It th t d f il System – Business process that failed Contributing – Aided the failure Detection – Allow problem to escape©2011 Duke Okes
  • 8. Where Are Root Causes? Process Previous Input Output Next that Process Process FailedTransactional LevelDevelopment Level Processes that Provide Resources • People – HR training HR, • Information – Engineering, quality, sales • Equipment – Engineering, maintenance • Materials – Procurement scheduling Procurement,©2011 Duke Okes
  • 9. How Far to Drill Down Is it outside something you can control or influence? What is the level of risk (probability, impact)? Is there data that indicates we didn’t go far enough previously? What are the opportunity costs?©2011 Duke Okes
  • 10. Treating Problems as Unique Batch #: 1 2 3 4 5 Attribute: OK O OK O OK O OK O NG G Measured Value Spec V Possibilities: ured Value Spec Measu Measured Value Va Spec©2011 Duke Okes
  • 11. TheImportance o of Visual Tools
  • 12. The DO IT2 Problem Solving Model P bl S l i M d l * IT means root cause of the problem!©2011 Duke Okes
  • 13. Engineering View of the Diagnostic Steps th Di ti St Step 1 – What is the problem? Step 2 – How is the system supposed to work? Step St 3 – I what ways could th system fail which In h t ld the t f il hi h would result in this specific problem? Steps 4&5 – Which possible causes does the scientific evidence indicate are/not at work in this case?©2011 Duke Okes
  • 14. How System is Supposed to Work - Flowchart Fl h t Design g Product Design Design Design Build Validation Input Decisions Verify Prototype Testing • Flowcharts, functional block diagrams, etc. • Logical or physical flow g p y • Be careful of getting too detailed too soon©2011 Duke Okes
  • 15. Levels of RCA Analysis Macro level – Process/time/factor variation Midi level – Within and between unit variation Micro level – Chemical, structural, etc. variation©2011 Duke Okes
  • 16. How System Could Fail - Logic Tree Clothes Not Getting Dry Why? Heating System Air Flow System Rotation System Why? Flow Restiction Supply Constraint Why? Creased Duct Lint Trap Why? High Lint No Regular Introduction Cleaning©2011 Duke Okes
  • 17. A (Partial) Complete Logic Tree Physical Level y System (Policy/Procedure) Level©2011 Duke Okes
  • 18. • What controls are in place that should have prevented the p Barrier problem, and did they fail?Analysis • Wh t controls are in place to What t l i l t detect the problem, and did they fail? • What combinations of barriers might have failed? • Note: Detection barriers can be valuable sources of data
  • 19. Change Analysis Questions to ask: What has changed (environment, equipment people process )? (environment equipment, people, process…)? When was it changed? Could the h C ld th changes b relevant t th problem? be l t to the bl ? Cautions: There may be a significant delay between when a change is made and when the impact is seen Pertinent changes may be in other processes not readily apparent to where the problem is found Th changes may b k The h be known or unknown ( k l d l d) (e.g., planned or unplanned)©2011 Duke Okes
  • 20. Data Collection & Analysis Teardown/failure analysis 5 human senses Pictograms/concentration diagram Interviews, Interviews process records Pattern analysis (time, sequence, batch, …)©2011 Duke Okes
  • 21. A Sequence for Drilling Down to Root Cause t R tC What failed? Problem symptoms Functions/subsystems How did it fail? Components Features Why did it fail? States System fault©2011 Duke Okes
  • 22. Cognitive Biases/Errors to W t h F t Watch For Recency effect Anchoring error Availability error Hindsight bias Confirmation bias Overuse heuristics O er se of he ristics©2011 Duke Okes
  • 23. Ultimate Objective of Root Cause A l i R tC Analysis Building institutional knowledge/memory to eliminate repeat occurrences of the same problem for the same cause(s) – the CA in PDCA But reliability professionals can also improve the PD in PDCA by forward flow of information about potential problems, causes, etc.©2011 Duke Okes
  • 24. Example Problem: Product failing in field field. Cause: An actuator inside the product was not robust enough for the application Action taken: Drop the product line (sales volume & margin were low).©2011 Duke Okes
  • 25. Contact Information Duke Okes 423-323-7576 423 323 7576 dokes@earthlink.net @ www.aplomet.com©2011 Duke Okes

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