QM-027-Problem Solving Techniques

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QM-027-Problem Solving Techniques

  1. 1. Problem Solving Techniques MST326 lecture 3 25 January 2007 MATS326-3 problem.ppt
  2. 2. Outline of lecture <ul><li>Brainstorming </li></ul><ul><li>Mind maps </li></ul><ul><li>Cause-and-Effect diagrams </li></ul><ul><li>Failures Mode and Effects Analysis </li></ul><ul><li>Fault Tree Analysis </li></ul><ul><li>Design of Experiments </li></ul>25 January 2007 MATS326-3 problem.ppt
  3. 3. Brainstorming <ul><li>proposed by Alex Osborn “for the sole purpose of producing checklists of ideas” </li></ul><ul><li>technique to identify causes and develop solutions to problems </li></ul><ul><li>“ seeking the wisdom of ten people rather than the knowledge of one person” [Kaizen Institute] </li></ul>25 January 2007 MATS326-3 problem.ppt
  4. 4. Brainstorming <ul><li>no criticism is permitted </li></ul><ul><ul><li>“ only stupid question is one that is not asked” [Ho] </li></ul></ul><ul><li>wild ideas are encouraged </li></ul><ul><ul><li>often trigger good ideas from someone else </li></ul></ul><ul><li>each person contributes one idea </li></ul><ul><ul><li>further single ideas on second circuit </li></ul></ul><ul><ul><li>repeat until no further ideas </li></ul></ul><ul><li>all contributions are recorded in view </li></ul>25 January 2007 MATS326-3 problem.ppt
  5. 5. Brainstorming <ul><li>Osborn proposed 75 fundamental questions </li></ul><ul><li>can be reduced to: </li></ul><ul><ul><li> seek other uses?  adapt? </li></ul></ul><ul><ul><li>modify?  magnify? </li></ul></ul><ul><ul><li>minify?  substitute? </li></ul></ul><ul><ul><li> rearrange?  reverse? </li></ul></ul><ul><ul><li> combine? </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  6. 6. TRIZ <ul><li>  Teorija Reshenija Izobretatel'skih Zadach </li></ul><ul><li>loosely translates as Theory of Inventive Problem Solving (TIPS) </li></ul><ul><li>40 Inventive Principles </li></ul>25 January 2007 MATS326-3 problem.ppt
  7. 7. 40 inventive principles of TRIZ <ul><li>IP 01: Segmentation IP 02: Taking out IP 03: Local quality </li></ul><ul><li>IP 04: Asymmetry     IP 05: Merging     IP 06: Universality </li></ul><ul><li>IP 07: Nested doll IP 08: Anti-weight IP 09: Preliminary anti-action </li></ul><ul><li>IP 10: Preliminary action IP 11: Prior cushioning IP 12: Equipotentiality </li></ul><ul><li>IP 13: The other way round IP 14: Spheroidality or curvature    IP 15: Dynamics </li></ul><ul><li>IP 16: Abundance IP 17: Another dimension IP 18: Mechanical vibration </li></ul><ul><li>IP 19: Periodic action IP 20: Continuity of useful action    IP 21: Rushing through     </li></ul><ul><li>IP 22: Blessing in disguise IP 23: Feedback IP 24: Intermediary </li></ul><ul><li>IP 25: Self-service IP 26: Copying     IP 27: Cheap short-lived objects </li></ul><ul><li>IP 28: Mechanics substitution IP 29: Pneumatics and hydraulics </li></ul><ul><li>IP 30: Flexible shells and thin films    IP 31: Porous materials IP 32: Colour change </li></ul><ul><li>IP 33: Homogeneity IP 34: Discarding and recovering    IP 35: Parameter change </li></ul><ul><li>IP 36: Phase transition IP 37: Thermal expansion IP 38: Strong oxidants </li></ul><ul><li>IP 39: Inert atmosphere IP 40: Composite materials </li></ul>25 January 2007 MATS326-3 problem.ppt
  8. 8. Mind maps <ul><li>attributed to Tony Buzan </li></ul><ul><ul><li>classic book “Use Your Head” </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  9. 9. Mind maps <ul><li>Image from http://www.loanedgenius.com/scrabble_2_letter_words.gif </li></ul>25 January 2007 MATS326-3 problem.ppt
  10. 10. Cause-and-Effect diagrams <ul><li>Cause-and-Effect diagram </li></ul><ul><ul><li>often referred to as a fishbone diagram </li></ul></ul><ul><ul><li>or an Ishikawa diagram </li></ul></ul><ul><li>introduced by Kaoru Ishikawa </li></ul><ul><ul><li>simple graphical method to record and classify a chain of causes and effects in order to resolve a quality problem </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  11. 11. Cause-and-Effect diagrams <ul><li>Clarify the object effect </li></ul><ul><li>Pick causes </li></ul><ul><li>Determine the priority causes </li></ul><ul><li>Work out the counteractions for priority causes </li></ul><ul><li>implement appropriate solutions to eliminate or reduce the causes of problems </li></ul>25 January 2007 MATS326-3 problem.ppt
  12. 12. Cause-and-Effect diagrams I <ul><li>Clarify the object effect </li></ul><ul><ul><li>a numerical measurement should be established against which subsequent improvement can be judged </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  13. 13. Cause-and-Effect diagrams II 25 January 2007 MATS326-3 problem.ppt <ul><li>Pick causes </li></ul><ul><li>create a team of people to brainstorm possible causes that may lead to the effect </li></ul><ul><li>study the actual effect in the problem environment </li></ul><ul><li>on a horizontal line draw diagonal branches for direct causes of the effect </li></ul><ul><li>using arrows onto the branches create sub-branches for appropriate secondary causes </li></ul><ul><li>confirm all elements of the diagram are correctly positioned </li></ul><ul><li>quantify the causes wherever possible </li></ul>
  14. 14. Cause-and-Effect diagrams III <ul><li>Determine the priority causes </li></ul><ul><ul><li>analyse any existing data for the problem </li></ul></ul><ul><ul><li>if practical, create a Pareto diagram.  </li></ul></ul><ul><ul><li>otherwise, determine a ranking of the relative importance of each cause. </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  15. 15. Cause-and-Effect diagrams IV <ul><li>Work out the counteractions for priority causes </li></ul><ul><ul><li>put in place appropriate solutions to eliminate or reduce the causes of problems </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  16. 16. Cause-and-Effect diagram: <ul><li>Image from http://www.ifm.eng.cam.ac.uk/dstools/gif/ishika.gif </li></ul>25 January 2007 MATS326-3 problem.ppt
  17. 17. Failures Mode and Effects Analysis <ul><li>FMEA is </li></ul><ul><ul><li>a useful tool for reliability analysis </li></ul></ul><ul><ul><li>systematic check of a product or process </li></ul></ul><ul><ul><ul><li>function </li></ul></ul></ul><ul><ul><ul><li>failure causes </li></ul></ul></ul><ul><ul><ul><li>failure modes </li></ul></ul></ul><ul><ul><ul><li>failure consequences </li></ul></ul></ul>25 January 2007 MATS326-3 problem.ppt
  18. 18. Failures Mode and Effects Analysis <ul><li>Requires a thorough knowledge of </li></ul><ul><ul><li>functions of the components </li></ul></ul><ul><ul><li>contribution of those components to function of the system </li></ul></ul><ul><li>For every failure mode at a low level, failure consequences are analysed at </li></ul><ul><ul><li>the local level </li></ul></ul><ul><ul><li>the system level </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  19. 19. Failures Mode and Effects Analysis <ul><li>FMEA is usually qualitative but may also be quantitative </li></ul><ul><li>initiated during planning and definition of a project to investigate qualitative reliability demands of the market </li></ul><ul><li>during design and development, for quantitative reliability activities </li></ul>25 January 2007 MATS326-3 problem.ppt
  20. 20. 25 January 2007 MATS326-3 problem.ppt Table From Evans and Lindsay Chapter 13
  21. 21. Failures Mode and Effects Analysis <ul><li>design-FMEA for design reviews </li></ul><ul><ul><li>definition and limiting of the system </li></ul></ul><ul><ul><li>choice of complexity level </li></ul></ul><ul><ul><li>check of component functions </li></ul></ul><ul><ul><li>check of system functions </li></ul></ul><ul><ul><li>identification of possible failure modes </li></ul></ul><ul><ul><li>identification of consequences of failures </li></ul></ul><ul><ul><li>possibility of failure detection and failure localisation </li></ul></ul><ul><ul><li>assessment of seriousness of failure </li></ul></ul><ul><ul><li>identification of failure causes </li></ul></ul><ul><ul><li>interdependence of failures </li></ul></ul><ul><ul><li>documentation </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  22. 22. Failures Mode and Effects Analysis <ul><li>quantitative design-FMEA a.k.a. FMECA Failure Mode, Effects and Criticality Analysis </li></ul><ul><ul><li>consider every component </li></ul></ul><ul><ul><li>quantify and rank different failure modes </li></ul></ul><ul><ul><ul><li>F = probability of failure </li></ul></ul></ul><ul><ul><ul><li>A = seriousness (consequences of failure) </li></ul></ul></ul><ul><ul><ul><li>U = probability of detection </li></ul></ul></ul><ul><ul><li>subjective judgements on a scale of 1-5 or 1-10 </li></ul></ul><ul><ul><li>Product (F*A*U) = Risk Priority Number (RPN) </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  23. 23. Failures Mode and Effects Analysis <ul><li>Process-FMEA for </li></ul><ul><ul><li>pre-production engineering </li></ul></ul><ul><ul><li>design of process control </li></ul></ul><ul><ul><li>process improvement </li></ul></ul><ul><li>FMEA is efficient where component failure leads directly to system failure </li></ul><ul><li>for more complex failures, FMEA may be supplemented by Fault Tree Analysis (FTA) </li></ul>25 January 2007 MATS326-3 problem.ppt
  24. 24. Some URLs for FMEA <ul><li>http://www.fmeainfocentre.com/ </li></ul><ul><li>http://supplier.intel.com/ehs/fmea.PDF </li></ul><ul><li>http://www.cs.mdx.ac.uk/puma/wp18.pdf </li></ul><ul><li>http://www.sverdrup.com/safety/fmea.pdf </li></ul><ul><li>http://www.uscg.mil/hq/msc/fmea.doc </li></ul><ul><li>http://www.competitiveedge.net/pdfs/fmea.pdf </li></ul><ul><li>http://www.fmeca.com/ffmethod/methodol.htm </li></ul><ul><li>http://www-personal.engin.umich.edu/~wmkeyser/ioe539/fmea.pdf </li></ul><ul><li>http://www.engin.umich.edu/class/eng401/003/LCNotes/fmea.pdf </li></ul>25 January 2007 MATS326-3 problem.ppt
  25. 25. Fault Tree Analysis <ul><li>Logical chart of occurrences to illustrate cause and effects </li></ul><ul><li>developed by DF Haasl, HA Watson, BJ Fussell and WE Vesely </li></ul><ul><li>initially at Bell Telephone Laboratories then North American Space Industry </li></ul>25 January 2007 MATS326-3 problem.ppt
  26. 26. Fault Tree Analysis <ul><li>Common symbols used 1 </li></ul><ul><ul><li>main event </li></ul></ul><ul><ul><li>basic event </li></ul></ul><ul><ul><li>incompletely analysed event </li></ul></ul><ul><ul><li>restriction </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  27. 27. Fault Tree Analysis <ul><li>Common symbols used 2 </li></ul><ul><ul><li>or-gate </li></ul></ul><ul><ul><li>and-gate </li></ul></ul><ul><ul><li>transfer to or from another place </li></ul></ul>25 January 2007 MATS326-3 problem.ppt &  1 +
  28. 28. 25 January 2007 MATS326-3 problem.ppt Figure From Evans and Lindsay Chapter 13
  29. 29. Design of Experiments <ul><li>originally conceived by Ronald Aylmer Fisher at Rothampstead Experimental Station during the 1920s </li></ul><ul><ul><li>analysing plant growing plots under different conditions, and needed to eliminate systematic errors. </li></ul></ul><ul><ul><li>Image from http://www.csse.monash.edu.au/~lloyd/tildeImages/People/Fisher.RA/ </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  30. 30. Experimental design <ul><li>Randomisation </li></ul><ul><li>Replication - repetition so that variability can be estimated </li></ul><ul><li>Blocking - experimental units in groups (blocks) which are similar </li></ul><ul><li>Orthogonality - statistically normal. </li></ul><ul><li>Use of factorial experiments instead of one-factor-at-a-time </li></ul>25 January 2007 MATS326-3 problem.ppt
  31. 31. Design of Experiments <ul><li>full factorial experiment </li></ul><ul><ul><li>where a number of factors may influence the output of a process, it is possible to study all combinations of levels of each factor </li></ul></ul><ul><ul><li>if the number of factors considered increases, then number of experiments required increases more rapidly.  </li></ul></ul>25 January 2007 MATS326-3 problem.ppt
  32. 32. Design of Experiments <ul><li>For two levels of n-variables, the number of experiments required is 2 n </li></ul><ul><ul><li>4 experiments for two variables (low-low, low-high, high-low and high-high) </li></ul></ul><ul><ul><li>16 experiments for four variables </li></ul></ul><ul><ul><li>64 experiments for six variables. </li></ul></ul><ul><li>If three levels (low - normal - high) or more are to be studied, then a full factorial experiment soon becomes impractical. </li></ul>25 January 2007 MATS326-3 problem.ppt
  33. 33. Design of Experiments <ul><li>results plotted to indicate the influence of each of the factors studied </li></ul><ul><li>when one factor affects the response, this is known as the main effect . </li></ul><ul><li>when >1 factor affects the response, this is termed an interaction . </li></ul>25 January 2007 MATS326-3 problem.ppt
  34. 34. Design of Experiments <ul><li>Genichi Taguchi developed orthogonal arrays </li></ul><ul><li>fractional factorial matrix </li></ul><ul><li>permits a balanced comparison of levels of any factor with a reduced number of experiments. </li></ul><ul><li>each factor can be evaluated independently of each of the other factors.  </li></ul>25 January 2007 MATS326-3 problem.ppt
  35. 35. Orthogonal arrays <ul><li>L4: three two-level factors </li></ul><ul><li>L9: four three level factors </li></ul><ul><li>Arrays from http://www.york.ac.uk/depts/maths/tables/orthogonal.htm </li></ul>25 January 2007 MATS326-3 problem.ppt
  36. 36. Common orthogonal arrays 25 January 2007 MATS326-3 problem.ppt Table from Tony Bendell “Taguchi Methods”, 1989 Array Levels Equivalent Full Factorial L 4 3 x 2 8 L 8 7 x 2 128 L 9 4 x 3 81 L 12 11 x 2 2 048 L 16 15 x 2 32 768 L 25 6 x 5 15 625 L 27 13 x 3 1 594 323
  37. 37. Taguchi <ul><li>Quality Loss Function L(x) = k ( x - t ) 2 </li></ul><ul><ul><li>L = the loss to society of a unit of output at value x   </li></ul></ul><ul><ul><li>t = the ideal target value </li></ul></ul><ul><ul><li>k = constant </li></ul></ul><ul><li>as non-conformance increases, losses increase even more rapidly </li></ul>25 January 2007 MATS326-3 problem.ppt

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