Sirris manufacturing day 2013 Nick Orchard

©2013 Nick OrchardThe 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.

Making the most of measurement

Nick Orchard

Measurement Spec i a l i s t

Br i s to l , UK

Sirris, Genk 5 November 2103

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

Measurement – why bother?

� Fit

� Form

� Function

Measurement – what’s it all about?

An example – measuring an oblate spheroid –


A simpler example – measuring an oblate spheroid –

Smarties or M&Ms


What is there to know?

DiameterThicknessRoundnessSurface profileSurface form – e.g. no curvature reversals (dips and bumps)Colour coating thicknessShell thicknessNo cracks, pits, scratchesWeightCoating melting pointChocolate melting pointColourTaste…

…a lot more than you’d think!

Something simpler still – a steel roller

� Size

� Diameter

� Length

Something simpler still – a steel roller

� Size

� Diameter

� Length L

D

Some tolerances?

� Size

� Diameter

� Length

� Form

L ± l

D ± d

Let’s make it a tube

� Size

� Diameter

� Length

� Form

L ± l

D ± d

E ± e

…now we’ll add an end flange…

� Size

� Diameter

� Length

� Form

L ± l

D ± d

E ± e

T ± t

F ± f

…and finally some bolt holes…

� Size

� Diameter

� Length

� Form

� Position

� Orientation

L ± l

D ± d

E ± e

T ± t

F ± f

8 HOLES EQU SP Ø G ± g

H ± h

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?

Instruments

The 150mm steel rule that lives in my top pocket

The rusty 0-1” micrometer that lives in my tool box

Instruments

The plastic dial caliperwith badly worn jaws The cheap digital caliper

from China with flexible jaws and a variable zero

The top class coolant-proof digital caliper

Instruments

A state-of-the-art coordinate measuring machine

Measuring size

Measuring size

Measuring size

Analogue scanning

B

┴ A0.005

0.005

∅ 221.259 ± 0.0075

The production of merlin engines at aRolls-Royce factory

© IWM (D 12100)

What happens when we invest in new measurement technology?

Following investment in new measurement capability, would you expect the overall process capability to:

a) Go up?

b) Go down?

c) Stay the same?

d) Don’t know?

e) Don’t care?

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

Something more complicated - Airbus A380

Source: Airbus SAS

The Rolls-Royce Trent 900 engines

Qantas flight QF32 4 November 2010

Source: Australian Transport Safety Bureau (Supplied by a passenger)

Qantas flight QF32 4 November 2010

Source: Australian Transport Safety Bureau (Supplied by a passenger)

Location of the cabin emergency call light

Source: Australian Transport Safety Bureau

Engine/warning display

Image source: Australian Transport Safety Bureau - Image taken during the occurrence

flight; supplied by a flight crew member

Flight path during the event

Source: Australian Transport Safety Bureau – image source: Google Earth

Fire-fighters ‘drowning’ the No. 1 engine with foam

Image source: Supplied by the Air Accident Investigation Bureau (AAIB) of Singapore.

General damage to the No. 2 engine


Damage to N0 2 engine


Damage to No 2 engine


Example of internal damage to the left wing (looking forward and up)


Example of wiring damage in the left wing (looking rearwards)


Damage to wiring in the belly fairing


Damage to buildings on the ground


When it all goes wrong

Trent 900 being mounted to the A380 wing

Source: Airbus SAS

Rolls-Royce Trent 900

This photograph is reproduced with the permission of Rolls-Royce plc, copyright © Rolls-Royce plc 2012

Trent 900 main rotating assemblies

Image source: Australian Transport Safety Bureau - Rolls-Royce RB211-Trent 900 Line and Base Maintenance training guide

IP turbine disc segment


Comparison of a diagrammatic representation of the IP turbine disc with the recovered segment of the disc


HP/IP bearing support structure


Oil leakage and fire

Image modified from a Rolls-Royce supplied model


Drive arm heating and disc separation from the drive shaft



Unrestrained IP turbine disc acceleration and burst



HP/IP bearing support structure


Cross section of a generic HP/IP hub with a service pipe


Cross section of a generic HP/IP hub with an oil feed stub pipe


Oil leak into the buffer space


Oil feed stub pipe feature terminology


Oil feed stub pipe fracture


Offset oil feed stub pipe counter bore


Cross-section of failed stub pipe


Representation of the design definition drawing that identified datum AA


Representation of the design definition drawing that defined the oil feed stub pipe counter bore


Inaccessibility of Datum AA with the oil feed stub pipe installed

Image source: UK AAIB Source: Australian Transport Safety Bureau

Representation of the manufacturing stage drawing that identified datum M


Representation of the manufacturing stage drawing that defined the oil feed stub pipe counter bore


Joining of the inner and outer hub castings

Source: Australian Transport Safety Bureau Image source: UK AAIB

Machining fixture clamping arrangement


OP 15 formation of the oil feed stub pipe holes


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.


Coordinate measuring machine


Graphical representation of the true positions of the bores and datum M on the oil feed stub pipe from hub 0225


CMM measurement of the stub pipe

The consequences…


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.

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.

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.

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 datumsneeds 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’.

A robust process

The process route Feedback, revision, checks

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!

Thank you for your attentionAny questions?

Nick [email protected]

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Sirris manufacturing day 2013 Nick Orchard

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