Sirris manufacturing day 2013 Nick Orchard

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Getting the most out of measurement

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Sirris manufacturing day 2013 Nick Orchard

  1. 1. Making the most of measurement Nick Orchard Measurement Specialist Bristol, UK ©2013 Nick Orchard The information in this document is the property of Nick Orchard and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Nick Orchard. This information is given in good faith based upon the latest information available to Nick Orchard, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Nick Orchard. Illustrations in this document are reproduced by Nick Orchard in accordance with the accreditation requirements of the sources. Sirris, Genk 5 November 2103
  2. 2. Measurement – what I’ll be talking about Why bother? Measuring oblate spheroids What do we actually need to measure? Effect of introducing better measurement What happens when we get it wrong? Lessons to learn
  3. 3. Measurement – why bother? Fit Form Function
  4. 4. Measurement – what’s it all about? An example – measuring an oblate spheroid –
  5. 5. Measurement – what’s it all about? A simpler example – measuring an oblate spheroid – Smarties or M&Ms
  6. 6. Measurement – what’s it all about? What is there to know? Diameter Thickness Roundness Surface profile Surface form – e.g. no curvature reversals (dips and bumps) Colour coating thickness Shell thickness No cracks, pits, scratches Weight Coating melting point Chocolate melting point Colour Taste… …a lot more than you’d think!
  7. 7. Something simpler still – a steel roller Size Diameter Length
  8. 8. Something simpler still – a steel roller Size Diameter Length L D
  9. 9. Some tolerances? Size Diameter Length Form L±l D±d
  10. 10. Let’s make it a tube Size Diameter Length Form L±l D±d E±e
  11. 11. …now we’ll add an end flange… Size Diameter Length L±l Form F±f D±d E±e T±t
  12. 12. …and finally some bolt holes… Size Diameter Length L±l Form Position Orientation F±f D±d H±h E±e T±t 8 HOLES EQU SP ØG±g
  13. 13. Roller measurement questions What instrument should be used? How many positions should the diameter be measured at? How many points per circle if not scanned? How should the diameter be calculated – Least-squares best fit? Average diameter? Minimum circumscribed circle? How do you assess form, position and orientation?
  14. 14. Instruments The 150mm steel rule that lives in my top pocket The rusty 0-1” micrometer that lives in my tool box
  15. 15. Instruments The plastic dial caliper with badly worn jaws The top class coolant-proof digital caliper The cheap digital caliper from China with flexible jaws and a variable zero
  16. 16. Instruments A state-of-the-art coordinate measuring machine
  17. 17. Measuring size
  18. 18. Measuring size
  19. 19. Measuring size
  20. 20. Analogue scanning
  21. 21. B ┴ 0.005 A ∅ 221.259 ± 0.0075 0.005
  22. 22. The production of merlin engines at a Rolls-Royce factory © IWM (D 12100)
  23. 23. What happens when we invest in new measurement technology? Following investment in new measurement capability, would you expect the overall process capability to: a) b) c) d) e) Go up? Go down? Stay the same? Don’t know? Don’t care?
  24. 24. Well it all depends… Is your measurement capability worse than your manufacturing capability? Do you know the relative capabilities of your manufacturing and measurement processes? Perhaps you have other reasons for improving your measurement systems, for example improving customer confidence or better data recording
  25. 25. Something more complicated - Airbus A380 Source: Airbus SAS
  26. 26. The Rolls-Royce Trent 900 engines
  27. 27. Qantas flight QF32 4 November 2010 Source: Australian Transport Safety Bureau (Supplied by a passenger)
  28. 28. Qantas flight QF32 4 November 2010 Source: Australian Transport Safety Bureau (Supplied by a passenger)
  29. 29. Location of the cabin emergency call light Source: Australian Transport Safety Bureau
  30. 30. Engine/warning display Image source: Australian Transport Safety Bureau - Image taken during the occurrence flight; supplied by a flight crew member
  31. 31. Flight path during the event Source: Australian Transport Safety Bureau – image source: Google Earth
  32. 32. Fire-fighters ‘drowning’ the No. 1 engine with foam Image source: Supplied by the Air Accident Investigation Bureau (AAIB) of Singapore.
  33. 33. General damage to the No. 2 engine Source: Australian Transport Safety Bureau
  34. 34. Damage to N0 2 engine Source: Australian Transport Safety Bureau
  35. 35. Damage to No 2 engine Source: Australian Transport Safety Bureau
  36. 36. Example of internal damage to the left wing (looking forward and up) Source: Australian Transport Safety Bureau
  37. 37. Example of wiring damage in the left wing (looking rearwards) Source: Australian Transport Safety Bureau
  38. 38. Damage to wiring in the belly fairing Source: Australian Transport Safety Bureau
  39. 39. Damage to buildings on the ground Source: Australian Transport Safety Bureau
  40. 40. When it all goes wrong
  41. 41. Trent 900 being mounted to the A380 wing Source: Airbus SAS
  42. 42. Rolls-Royce Trent 900 This photograph is reproduced with the permission of Rolls-Royce plc, copyright © Rolls-Royce plc 2012
  43. 43. Trent 900 main rotating assemblies Image source: Australian Transport Safety Bureau - Rolls-Royce RB211-Trent 900 Line and Base Maintenance training guide
  44. 44. IP turbine disc segment Source: Australian Transport Safety Bureau
  45. 45. Comparison of a diagrammatic representation of the IP turbine disc with the recovered segment of the disc Source: Australian Transport Safety Bureau
  46. 46. HP/IP bearing support structure Source: Australian Transport Safety Bureau
  47. 47. Oil leakage and fire Source: Australian Transport Safety Bureau Image modified from a Rolls-Royce supplied model
  48. 48. Drive arm heating and disc separation from the drive shaft Source: Australian Transport Safety Bureau Image modified from a Rolls-Royce supplied model
  49. 49. Unrestrained IP turbine disc acceleration and burst Source: Australian Transport Safety Bureau Image modified from a Rolls-Royce supplied model
  50. 50. HP/IP bearing support structure Source: Australian Transport Safety Bureau
  51. 51. Cross section of a generic HP/IP hub with a service pipe Source: Australian Transport Safety Bureau
  52. 52. Cross section of a generic HP/IP hub with an oil feed stub pipe Source: Australian Transport Safety Bureau
  53. 53. Oil leak into the buffer space Source: Australian Transport Safety Bureau
  54. 54. Oil feed stub pipe feature terminology Source: Australian Transport Safety Bureau
  55. 55. Oil feed stub pipe fracture Source: Australian Transport Safety Bureau
  56. 56. Offset oil feed stub pipe counter bore Source: Australian Transport Safety Bureau
  57. 57. Cross-section of failed stub pipe Source: Australian Transport Safety Bureau
  58. 58. Representation of the design definition drawing that identified datum AA Source: Australian Transport Safety Bureau
  59. 59. Representation of the design definition drawing that defined the oil feed stub pipe counter bore Source: Australian Transport Safety Bureau
  60. 60. Inaccessibility of Datum AA with the oil feed stub pipe installed Source: Australian Transport Safety Bureau Image source: UK AAIB
  61. 61. Representation of the manufacturing stage drawing that identified datum M Source: Australian Transport Safety Bureau
  62. 62. Representation of the manufacturing stage drawing that defined the oil feed stub pipe counter bore Source: Australian Transport Safety Bureau
  63. 63. Joining of the inner and outer hub castings Source: Australian Transport Safety Bureau Image source: UK AAIB
  64. 64. Machining fixture clamping arrangement Source: Australian Transport Safety Bureau
  65. 65. OP 15 formation of the oil feed stub pipe holes Source: Australian Transport Safety Bureau
  66. 66. OP 190 oil feed stub pipe counter bore Note: The wall thickness of the oil feed stub pipe is not shown to scale and has been exaggerated for clarity. Source: Australian Transport Safety Bureau
  67. 67. Coordinate measuring machine Source: Australian Transport Safety Bureau
  68. 68. Graphical representation of the true positions of the bores and datum M on the oil feed stub pipe from hub 0225 Source: Australian Transport Safety Bureau
  69. 69. CMM measurement of the stub pipe
  70. 70. The consequences… Source: Australian Transport Safety Bureau
  71. 71. Report conclusions During the manufacture of the HP/IP bearing support assembly fitted to the No. 2 engine (serial number 91045), movement of the hub during the machining processes resulted in a critically reduced wall thickness within the counter bore region of the oil feed stub pipe. It was probable that a non-conformance in the location of the oil feed stub pipe interference bore was reported by the coordinate measuring machine during the manufacturing process, but that the non-conformance was either not detected or not declared by inspection personnel, resulting in the assembly being released into service with a reduced wall thickness in the oil feed stub pipe.
  72. 72. Report conclusions During preparation of the manufacturing process for the HP/IP bearing support assembly structure, a manufacturing datum was introduced because the location of the oil feed stub pipe counter bore could not be referenced to the design definition datum. That manufacturing datum was not constrained to the location of the oil feed stub pipe and as such could not ensure that the counter bore was concentric with the stub pipe, as the designers had intended. The use by an inspector, during the first article inspection process, of the manufacturing stage drawings to verify the oil feed stub pipe counter bore features precluded the inspection from showing that the manufacturing process could produce an item that conformed to the design definition, or the intention of the design.
  73. 73. Report conclusions During the production of a number of HP/IP bearing support assemblies, the coordinate measuring machine identified a non-conformance in the location of the oil feed stub pipe interference bore. It was likely that when making the determination that the non-conforming HP/IP bearing support assemblies were acceptable for use, the manufacturing personnel did not know that the coordinate measuring machine referenced a different datum to the design definition drawings and unknowingly released thin-walled pipes into service based on an alternative (wire gauge) measurement method.
  74. 74. So what can we learn from this? In a complex system, there is no such thing as a ‘simple’ component. Every dimension on every feature must be considered carefully when planning the measurement process. The relationship between designer and manufacturing engineer is extremely important. The transfer of component datums from the final drawing features to part-finished manufacturing datums needs to be done with great care and attention to detail. Manufacturing operations must develop a culture of ‘microns matter’. There should be no opportunity for people to make their own judgement on when a measured feature is ‘near enough’.
  75. 75. A robust process The process route Feedback, revision, checks
  76. 76. Please don’t panic! An RB211-535 has run 42743 hours without a shop visit = 16 hours/day for 7 years or about 30,000,000 km!
  77. 77. Thank you for your attention Any questions? Nick Orchard nborchard@blueyonder.co.uk

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