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Key Characteristics Goals of this class– Introduce Key Characteristics (KCs)– Define the notions of KC delivery and KC delivery chain– Understand the relationship between KC delivery chains and partto-part location– Appreciate how many KCs an assembly can have, including theconcept of KC conflict– See some examplesKCs 04.ppt9/13/2004 Daniel E Whitney1

Key Characteristics (KCs) Key characteristics are product requirements that demandattention because– they are critical for performance, safety, or regulations– AND– they are at risk of not being achieved due to process variations Usually, KCs are geometric relationships between featureson non-adjacent parts Two basic issues for KCs are– priorities– flowdownKCs 04.ppt9/13/2004 Daniel E Whitney2

“Chain of Delivery” of QualityImage removed for copyright reasons.Source:Figure 2-1 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.No single part “delivers” the KC.KCs 04.ppt9/13/2004 Daniel E Whitney3

Chains Deliver KCs KCs are delivered by chains that must operaterepeatibly Chains are made up of:µµµphysical elements: parts, sub-assemblies, tools, and fixturesthe associated organizations (supply chain)the capability of the processes (technology) Each KC is delivered when its chain is completeKCs 04.ppt9/13/2004 Daniel E Whitney4

KC Priorities Everything is important to someone KCs should be confined to things that are not onlyimportant but are at some risk of not beingachieved Usually, manufacturing or assembly variation areconsidered to be the main threat So there is a direct link between KCs andassembly tolerances If there is no systematic process for identifyingKCs, and if priorities are not assigned, then KCstend to proliferateKCs 04.ppt9/13/2004 Daniel E Whitney5

When Can Key Characteristics Be Used? During concept design, to capture customer req’mts During system engineering, to flow down req’mtsto lower levels of the design process During detail design, to deliver req’mts via tolerancesand process planning During supplier selection and preparation of specs,to define deliverables During program management, to track and assureachievement of requirementsKCs 04.ppt9/13/2004 Daniel E Whitney6

KCs 04.ppt9/13/2004 Daniel E WhitneyDesktop StaplerImage removed for copyright reasons.Source:Figure 1-1 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.7

KCs 04.ppt9/13/2004 Daniel E WhitneyStapler PartsImage removed for copyright reasons.Source:Figure 1-2 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.8

Stapler KCsKCs 04.ppt9/13/2004 Daniel E Whitney9

Each KC is Delivered by a Chain“Chains of BASE“Key Characteristics (KCs)”KCs 04.ppt9/13/2004 Daniel E Whitney10

Key Characteristics and the LiaisonDiagramImage removed for copyright reasons.Source:Figure 1-3 in [Whitney 2004] Whitney, D. E.Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development.New York, NY: Oxford University Press, 2004.ISBN: 0195157826.Image removed for copyright reasons.Source:Figure 1-4 in [Whitney 2004] Whitney, D. E.Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development.New York, NY: Oxford University Press, 2004. ISBN: 0195157826.Liaison DiagramKCs 04.ppt9/13/2004KCs Daniel E Whitney11

Only Some Liaisons Matter in KCDeliveryImage removed for copyright reasons.Source:Figure 1-5 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney12

The Delivery Path for Each Stapler KCImage removed for copyright reasons.Source:Figure 1-6 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney13

Optical Disk Drive KCsImages removed for copyright reasons.Source:Figure 2-7 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney14

KC Flowdown Product KCs can be defined for customerrequirements and then decomposed intolower level Assembly and Manufacturing KCs Achievment of the PKCs requiresachievement of the AKCs and MKCs Full implementation requires that each AKCand MKC meet a specific tolerance or Cpk Suppliers’ capability may limit AKCs and MKCs,requiring flow-up and negotiationKCs 04.ppt9/13/2004 Daniel E Whitney15

Some “Statistics” A person at GM said– 60% of body sheet metal tolerances can be met– 40% must be altered to meet shop capabilities A patent from Boeing on tolerancing says that typically 8parts are involved in a tolerance chain (probably similar tothe length of a KC chain for us) A survey of 600 consumer products by Ulrich and Ellisonreveals that about 6 parts are involved in deliveringfunctions that differentiate the product in the marketplace You don’t get real numbers like this every dayKCs 04.ppt9/13/2004 Daniel E Whitney16

How Parts Locate Each Other to DeliverQuality at the Customer LevelDOORCRAFTMANSHIP KCCAR BODYKC Key CharacteristicBODY TOHINGE FLAP1: 6 DOFHINGE FLAP 1 TOHINGE FLAP 2: 5 DOFHINGE FLAP 2 TODOOR: 6 DOFKCs 04.ppt9/13/2004 Daniel E Whitney17

CUSTOMERPERCEPTIONOF DOORDOOR CLOSINGFORCEWATER LEAKAGEAND WIND YALIGNMENTUP/DOWN ANDFORE/AFTDOOR MOUNTINGMETHOD ANDEQUIPMENTDOOR ATTACHMENTTO BODYDOOR FRAMEPERIMETERSHAPE ACCURACYDOOR PERIMETERSHAPE ACCURACYBODY ASSEMBLYMETHOD ANDEQUIPMENTDOOR ASSEMBLYMETHOD ANDEQUIPMENTDOOR PARTSASSEMBLYBODY PARTSFABRICATIONDOOR PARTSFABRICATION9/13/2004SEAL ATTCHMENTTO BODY}}DOOR THICKNESSACCURACYBODY PARTSASSEMBLYKCs 04.pptHINGE ATTACHMENTTO DOOR}}} Daniel E WhitneyDOORSUBSYSTEM KCSSUBSYSTEMASSEMBLYPROCESS KCSSUBASSEMBLYPROCESS KCSPARTS FAB ANDASSEMBLY KCS18Car Door KC FlowdownFLUSHNESS OFDOOR-BODYSURFACESUNIFORMITY OFDOOR-BODY GAPSCUSTOMERREQUIREMENTS:PRODUCT KCS

KCs 04.ppt9/13/2004 Daniel E WhitneyCar Door Exterior GapsImage removed for copyright reasons.Source:Figure 2-8 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.19

Door AssemblyImage removed for copyright reasons.Source:Figure 2-10 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney21

How Doors are BuiltImages removed for copyright reasons.Source:Figure 2-10 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney22

Door HemKCs 04.ppt9/13/2004 Daniel E Whitney23

Car Door Design KCsSide ViewTop Viewup-downA PillarB PillarWeather seal KC dependson placement of theinner panelA PillarB PillarHingesOuterFenderLatchbarfore-aftdoor tolerances and fitKCs 04.ppt9/13/2004OuterFenderAppearance KC dependson placement of theouter panelin-outAppearance KC uniformity ofthis gap Daniel E Whitney25

Two Door Methods - There Are Many 6 DOF LOCATIONDOORHINGESHINGESDOORHINGE-MOUNTING FIXTUREDOOR MOUNTING FIXTUREAssembly Step 1aAssembly Step 2aLOCATORCONESHINGESDOORHINGESDOORHINGE-MOUNTING FIXTUREAssembly Step 1bKCs 04.ppt9/13/2004Assembly Step 2b Daniel E Whitney26

KC Conflict in Door AssemblyDifficult to achieve bothKCs this way!Impossibleto assemblethis way!Attach door outerto door inner,aligning partsAlign door innerto seal, then attachinner to frameAlign door outerto frame gaps, thenattach outer to innerMount door (inner outer)to frame and align seals,possibly misaligning gapsMount door (inner outer)to frame and align gaps,possibly misaligning sealsNot enough independent DOF availableKCs 04.ppt9/13/2004 Daniel E Whitney27

Ford Hinge MountingImage removed for copyright reasons.Source:Figure 2-12 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney28

Ford Hinge Mounting FixturePhoto removed due to copyright restrictions. (Detail of car door front and rear locator pins and holders for hinges.)KCs 04.ppt9/13/2004 Daniel E Whitney29

Door on Hinge-Mounting FixturePhoto removed due to copyright restrictions. (Detail of front and rear car door mounting locators.)KCs 04.ppt9/13/2004 Daniel E Whitney30

Ford Door Mounting to CarImages removed for copyright reasons.Source:Figure 2-12 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney32

Mustang Body in WhitePhoto removed due to copyright restrictions. (Detail of car door front and rear locators.)KCs 04.ppt9/13/2004 Daniel E Whitney33

34Door Mounting Tool for MustangImage removed for copyright reasons.Source:Figure 8-48 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.

An Interesting Wrinkle Doors are usually installed on a car beforepainting and removed for trim installation– you can grab a door rigidly (accurately) when there isno paint to scratch– it is easier to install stuff on/in the door and in the car ifthe doors are separate The challenge is to get them back on in the rightplace without the benefit of assembly tooling It is done cleverly with the hinges– install door hinges to car, remove door from hinges– remove a temporary hinge pin, reinstall a final one– check which bolts have paint to see how it was doneKCs 04.ppt9/13/2004 Daniel E Whitney35

GM Hinge MountingImage removed for copyright reasons.Source:Figure 2-12 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.GM MethodKCs 04.ppt9/13/2004 Daniel E Whitney37

GM Take-apart Car Door HingesPhoto removed due to copyright restrictions. (Detail of car door hinges and locator cone.)KCs 04.ppt9/13/2004 Daniel E Whitney38

GM Door Mounting to CarImages removed for copyright reasons.Source:Figure 8-47 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney39

Ford Locator DrawingImage removed for copyright reasons.Source:Figure 2-13 in [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture,and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826.KCs 04.ppt9/13/2004 Daniel E Whitney40

Conclusions KCs are the link between functional customer needs andphysical realizations at the assembly level KCs are delivered by chains of parts KCs can be delivered in more than one way Design of KC delivery requires definition of locationschemes by which parts are related to each other in 6 dof Assemblies typically have many KCs, and they canconflictKCs 04.ppt9/13/2004 Daniel E Whitney41

- Appreciate how many KCs an assembly can have, including the concept of KC conflict - See some examples KCs_04.ppt 9/13 . [Whitney 2004] Whitney, D. E. Mechanical Assemblies: Their Design, Manufacture, and Role in Product Development. New York, NY: Oxford University Press, 2004. ISBN: 0195157826. No single part "delivers" the KC. KCs .