‘Green’&GoldCase

OtterProducts

ColoradoStateUniversity

MechanicalEngineeringSeniorDesign

2015-2016

FinalReport

April28,2016

Team:

JulieCox:jkcox@rams.colostate.edu ______________________________

AlexHeape:heapea@rams.colostate.edu _____________________________

KristenOssolinski:college.kdo@gmail.com ______________________________

CorinnePellish:corinne.pellish@gmail.com ______________________________

AmandaWilson:wilsoac@rams.colostate.edu ______________________________

OtterProductsAdvisor:

JeremyPutka:jeremy.putka@otterproducts.com ______________________________

CSUAdvisor:

Dr.MitchellStansloski:mjs@engr.colostate.edu ______________________________

1ListofIllustrationsOtter Products ‘Green’ and Gold Case

TableofContentsListofIllustrations.......................................................................................................................................2

ExecutiveSummary.....................................................................................................................................3

Acknowledgements.....................................................................................................................................5

Introduction.................................................................................................................................................6

ProblemStatement..................................................................................................................................6

Background/History.................................................................................................................................6

DesignProblemAnalysis..............................................................................................................................8

CustomerandEnd-UserNeeds................................................................................................................8

Objectives................................................................................................................................................8

Constraints...............................................................................................................................................9

DesignSummary........................................................................................................................................11

DesignDecisions........................................................................................................................................12

ConceptSelection..................................................................................................................................13

FinalConcept.........................................................................................................................................13

GeometricModeling..........................................................................................................................14

PreliminaryTestingAnalysis..............................................................................................................16

FailureModesandEffectsAnalysis...................................................................................................18

DetailedDesign&SupportingAnalysis......................................................................................................20

Modeling&Analysis..............................................................................................................................20

Manufacturability&AssemblyConsiderations.....................................................................................21

ProductionUnit-CostAnalysis...............................................................................................................26

FinalEvaluation.........................................................................................................................................26

ManufacturingandAssembly................................................................................................................26

TestingandRefinement.........................................................................................................................28

ProjectCostSummary...........................................................................................................................29

Summary&ExplanationsforDeviationsfromOriginalPlan.................................................................30

Conclusions&Recommendations.............................................................................................................31

FutureRecommendations.....................................................................................................................31

References.................................................................................................................................................32

Appendix....................................................................................................................................................33

2ListofIllustrationsOtter Products ‘Green’ and Gold Case

ListofIllustrationsEquation1..................................................................................................................................................29

Figure1:DesignModificationsfromOtterProductsCommutertoSeniordesignModel........................12 Figure2:InitialGeometricModel..............................................................................................................15 Figure3:ScreenContactAngleCADModel...............................................................................................15 Figure4:HomeButtonKeepOutCone.....................................................................................................15 Figure5:CameraCutout............................................................................................................................16 Figure6:PCPostTesting,Thermal,Abrasion,&ChemicalTest................................................................17 Figure7:TPEPostTesting,Thermal,Abrasion,&ChemicalTest..............................................................17 Figure8:TPEPostMechanicalTesting......................................................................................................18 Figure9:FinalDesignChanges.................................................................................................................21 Figure10:TPEWallthicknesscorrections.................................................................................................22 Figure11:AirTraps&SinkMarks..............................................................................................................22Figure12:Turbulent/LaminarFlow(left)PressuretoFill(right)...............................................................23 Figure13:InjectionorientationonPC&InjectionsiteforTPE.................................................................24 Figure14:PartingLineofthePC...............................................................................................................24 Figure15:ModifiedCameraCutoutwithLifter.........................................................................................25 Figure16:TPEPartShowingDirectionofSlider........................................................................................26 Figure17:RenderedCADofPCToolSideB...............................................................................................27 Figure18:TPEDataSheet..........................................................................................................................33 Figure19:PCDataSheet...........................................................................................................................34 Figure20:OverlayofCoefficientofRestitutionforVirginandRecycledTPE............................................37 Table1:MaterialObjectives........................................................................................................................8 Table2:DesignObjectives...........................................................................................................................9 Table3:MaterialConstraints....................................................................................................................10 Table4:DesignConstraints.......................................................................................................................11 Table5:DesignDecisionMatrix................................................................................................................12 Table6:ToolingDecisionMatrix...............................................................................................................13 Table7:TPEMechanicalTestingData.......................................................................................................18 Table8:FMEAAnalysis..............................................................................................................................18 Table9:MitigationplanforFMEA.............................................................................................................19 Table10:DurabilityTestingData...............................................................................................................28 Table11:CompatibilityTestingData.........................................................................................................28 Table12:FinalBudget...............................................................................................................................30 Table13:ImpactTestingData-EnergyAbsorption..................................................................................34 Table14:ImpactTestingData-MaximumForce......................................................................................35 Table15:CoefficientofRestitution,e,forVirginTPE...............................................................................36 Table16:CoefficientofRestitution,e,forRecycledTPE...........................................................................36

3ExecutiveSummaryOtter Products ‘Green’ and Gold Case

ExecutiveSummary

OtterProducts,alocalcellphonecasecompany,partneredwithColoradoStateUniversityMechanicalEngineeringstudents.Thegoalwastocreateauniquecasedesignmadefrom100%recycledOtterBoxcases.Throughworkingwiththeindustry,theteamwasabletounderstandthebusinessstandardsfordesign.Currently,OtterBoxutilizes20-25%recycledcasesintheirproductstoday.Thereareconcernswiththeuseofrecycledmaterials,includingstrengthandchemicalproperties.Allofthiswastakenintoaccountduringtheproject. OtterProductsdesignsmobilecasesusingveryadvancedsurfacemodelinginSolidworks.Creatingamid-surfaceplanesplitbetweenthepolycarbonate(PC)andthermoplasticelastomer(TPE)allowsforchangestobemadeeffectivelyandefficiently.Additionally,thecaseopenings,suchasfortheplugsandcamera,arecreatedinthismid-surfaceforaccuratemeshingbetweenthetwomaterialsandforanypossiblechanges.Theseadjustmentshappeninthemid-surfaceandautomaticallypopulateinboththePCandTPEparts. Whenthecasewasdesigned,rulesfrombothAppleandOtterProductswerefollowed.Applehaskeep-outconeswherethecasecannotintrudeinthecone.Examplesoftheseareasincludeaccesstothecamera/flash,homebuttonandscreen.TherearedesignstandardsthatOtterProductsfollowsinordertomanufactureasuccessfulcaseandtokeepdesignsconsistentbetweenmodels.Forexample,whenitcomestodesigningthebuttons,OtterProductsoffersdistancesandthicknessesthataresuggestedformanufacturingasuccessfulbutton. Afterthecasedesignwascompleted,theCADfilesweresubmittedforaCADreview.ThisCADreviewentailedamold-flow,draftangle,directionofpullandthicknessanalysis.OncetheCADwasapproved,itwassubmittedtothetoolingmanufacturer(BroadwayChina)throughaDesignforManufacture(DFM). Forthecasetoproperlybemanufactured,thereweremultipledesignconsiderationstoensureaflawlessmold.Keyaspectstoconsiderwhendesigningforaninjectionmoldedpartare:wallthicknesses,directionofpull,andavoidingundercuts.Designingaparttohavenominalwallthicknessisessentialinordertoavoidsink.Sinkoccurswhentheouterlayerofplasticcoolsbeforetheinsidecausingtheinsidetocollapseonitself.Whenthematerialistoothick,thepartwillhavedifferentcoolingrates.Topreventthis,coringcutoutswereaddedaroundtheinsideedgeswheretheouterplasticdoesnotcovertheTPE.Anothercrucialpiecetoconsideristhedirectionofpull.Thisisthedirectionthatthetoolwillcomeaparttoreleasethepart.Thesolutionforthisistoapply3-5degreedraftanglesinthesamerouteasthedirectionofpull.Draftanglesareimplementedfortworeasons;forthedirectionofpullandtoavoidcreatingundercuts.Undercutswillgetcaughtonthelifterscausingtheparttobreak. Thefinalcase,madewith100%recycledOtterBoxcases,wentthroughaseriesofstandardtestsincludingenvironmental,abrasion,chemical,durability,andcompatibilitytests.TherecycledcasepassedallofOtterBox'sstandarddurabilitytesting,whichincludes26dropsatdifferentorientationsfrom4feettoplywood,aswellas100continuousdropsinapursefromonemeter.Additionally,thecasepassedallcompatibilitytesting,includingbutton,call,andsensortesting.Whenputthroughaseriesofenvironmentaltests,thecasesawnochangefrompretoposttesting.Whentestedfor

4ExecutiveSummaryOtter Products ‘Green’ and Gold Case

chemicalandabrasionresistance,therecycledcasesawminorvisualfailure.However,whentestedagainstthevirgincases,thesamefailureswereobserved.Inshort,therecycledcasepassedalltestingrequiredforproductvalidation. Apendulumimpacttesterisusedtodeterminehowamaterialrespondstodeformation.Itworkswhenaloadisappliedathighspeedsandcomesincontactwiththematerial.It.TheTPEwentthroughdifferentsimulatedheightsinordertounderstandthematerial’sresponse.Thedataacquiredbythependulumimpacttesterincludedtheenergyabsorbed(measuredinpercentage),theforcetransmittedthroughthematerial(measuredinpounds-force),andthereboundangleofthependulumarm(measuredindegrees).TherecycledandvirginTPEweretestedandcomparedtoeachother.TherecycledTPEabsorbedmoreenergythanthevirginTPE.Specifically,therecycledTPEabsorbed0.75%moreenergythanthevirginTPEatasimulatedheightofthreefeet.Inrespecttothemaximumforce,therewaslessforcetransmittedthroughtherecycledTPE.Atasimulatedheightofthreefeet,therecycledTPEtransmittedroughly226lbflessthanthevirginTPE.Finally,thereboundangle,orbounce-backangle,wasusedtocalculatetheCoefficientofRestitution.TheCoefficientofRestitutionisameasurementoftheamountofkineticenergyduringacollision.Atasimulatedheightofthreefeet,theCoefficientofRestitutionforthevirginTPEwas0.15whileitwas0.12fortherecycledTPE.ThisdatafromthependulumimpacttestershowedtherecycledTPEismoreelastic.Essentially,therecycledTPEabsorbsmoreenergyandhaslessforcetransmittedthroughit.ThisisanimprovementfromthevirginTPE.TherecycledTPEwillprovidebetterimpactprotectionthanthevirginTPE.

Overall,theOtterBox“Green&Gold”CasedesignedbytheColoradoStateUniversityMechanicalEngineeringseniordesignteamwassuccessful.Auniquecellphonecasemadefrom100%recycledOtterBoxcaseswithstoodrigoroustesting.OtterProductshastakenintoaccountthismaterialtestingandwilllooktoexploremoreoptionswiththecollecteddata.

5AcknowledgementsOtter Products ‘Green’ and Gold Case

Acknowledgements

TheCSUSeniorDesignteamisextremelythankfulforalloftheopportunitiesOtterProductsandColoradoStateUniversityhaveprovided.WeareespeciallygratefulforthetimeOtterProductsemployeesspentwithus.Togetherwesuccessfullycompletedaprojectofthiscaliberfrombeginningtoend.Someofthemajoropportunitiesinclude-learningadvancedsurfacemodeling,prototyping,polycarbonateandthermoplasticelastomermaterialproperties,plasticinjectionmolding,padprintingmanufacturing,testingmaterialsandhowasuccessfulbusinessoperates.TheOtterProductsteamwaseagertoteachandalwayswillingtohelp.WearegratefulfortheresourcesandopportunityColoradoStateUniversityprovideustoworkintheindustry.

Specifically,fromOtterProducts–

Name Title DepartmentJeremyPutka CustomerQualityEngineer ProductQualityJamieJohnson DirectorTechnologyDevelopment MechanicalEngineeringThomasVincent AssociateEngineer ManufacturingandToolingEngineeringJonGuerdrum Sr.MechanicalEngineer MechanicalEngineeringKingsleyMeldrum PrincipalToolingEngineer ManufacturingandToolingEngineeringEphraimMammo Sr.MaterialsEngineer ManufacturingandToolingEngineeringBrycenSmith TechnicianSupervisor MechanicalEngineeringJamesPrestien Sr.MechanicalEngineer MechanicalEngineeringZachDunkin Sr.Technician MechanicalEngineeringAdamSelby Sr.Technician MechanicalEngineeringTerraEberle Receptionist ExecutiveSupportJasonGriffin SpecialistEvents ShopperMarketing Specifically, from Colorado State University –

Name Title DepartmentMitchellStansloski

ProfessorofPracticeProjectAdvisor

DepartmentofMechanicalEngineering

PaulColasuonno TeachingAssistant DepartmentofMechanicalEngineering

DonRadford

ProfessorofMechanicalEngineering,andDirector, CompositeMaterials,ManufactureandStructuresLaboratory

DepartmentofMechanicalEngineering

6IntroductionOtter Products ‘Green’ and Gold Case

Introduction

Asthetimeschange,bothpeopleandcompaniesarestartingtobecomemoreconsciousoftheenvironmentandtheseekwaystoconserveitsresources.Businessesarelookingfornewopportunitiesnotonlyforsustainable,marketableproductsbutalsonewstrategiestohelpreducetheircarbonfootprintintheworld.OtterProductshasteamedupwithColoradoStateUniversityforthiseco-friendlymindsetbyproducinganewanduniquephonecasethatismadeoutof100%recycledOtterBoxcases.Asaresultofthisinitiative,OtterProductscanrepurposematerialstoimprovesustainabilitycompany-wide.ThiscasereflectsOtterProduct’smissiontoconfidentlyprotectthemobileworld.

ProblemStatement

Forthisproject,thetargetmarketwillbeecofriendlyconsumers.Withoutadurable,recycledcaseonthemarkettoday,OtterProductswouldtakethemarketshareinthisarea.ThetransportationmethodofdistributingtheproducttocustomerwillusecurrentOtterProductsapproaches.Examplesoffutureendusersincludebusinessprofessionalsandstudents.OtterProducts,materialdistributors,andmarketshareholdersaresomeofthestakeholderstomakethiscaseasuccessfulone.

OtterProductsininterestedinutilizingmoreregrindintheirproducts.However,thatcomeswithprovidingthesamelevelofprotectionguaranteetheirproductsoffer.Recycledmaterialcomeswithitschallenges,includingensuringtheintegrityofthematerial.Therearelimitedcellphonecasesonthemarketthataremadefrom100%recycledmaterialsbutnoneofthempromisethesamelevelofprotection.

Background/History

OtterBoxwasfoundedin1998withasolefocusonthedevelopmentofpackagingboxes.In2005,thefirstwaterproofcasethatalloweddeviceinterfacewasinvented.OtterBox,atthistime,decidedtomovetowardthetechnologysphere.Theybegantofocusonmobiledevices,includingcellphonesandtablets.In2007,OtterBoxlaunchedtheirfirstprotectivecaseseries:theDefender.TheDefenderisknownforitssuperiorthree-layerprotection.Twoyearslater,OtterBoxreleasedaslimmercaseresponsibleforlife’severydayblunders:theCommuter.TheCommuterofferstwolayerprotectionforpersonaldeviceswhileupholdingasleek,andpocketfriendlyprofile.TheCommuterwasdesignedforworkingprofessionalsthatneedprotectionfor“livinglifeon-the-go.”OtterBoxacquiredtheirlargestcompetitor,LifeProof,in2013andreestablishedthemselvesasOtterProducts.Thetwocompaniesoperatetogetherbutmarketseparately[1].

Currently,OtterProductsutilizestwotypesofmaterialfortheirCommuterdesign:polycarbonate,PC,andthermoplasticelastomer,TPE.Thepolycarbonateistheoutershellofthetwo-piecedesign;thermoplasticelastomeristheinnerportion,encompassingthemobiledevice.Eachmaterialismeltedandinjectionmolded.Thevirginmaterial,ormaterialthathasneverbeenprocessedbefore,ismixedwithapercentageofregrind.Regrindisamaterialthathasbeenprocessedatleastonceandismechanicallygroundupintosmallpellets[2].Processesincludemeltingandblending.The

7IntroductionOtter Products ‘Green’ and Gold Case

methodofremovingthemoldedcasefromthegateandrunnersystemprovidesextrascrapmaterial.TheregrindOtterProductsiscurrentlyusingcomesfromthedeburringandcleaningoftheircasesafterinjectionmolding.Thesescrapsarereferredtoasrunnersandsprues.Regrindcanalsocomefromthecollectionofcasesthatnevermadeittomarketorwholecasesduetodeformitiesordefects.ThesecaseswereputthroughaseriesofOtterProductsstandardizedtests.Thesecasesareinpristineconditionwithnoimpurities.

Thecurrentallowablepercentagesofregrind,orrecycledmaterial,thatOtterProductsincorporatesintotheircasesare25%forthepolycarbonateand20%forthethermoplasticelastomer.Throughpriortesting,theydiscoveredthesepercentagesofregrindwithinthecasesdonotaffecttheintegrityofthematerial.Intheirindustrialcomplexes,manyproductsarerecycledintoorproduceregrind.Theregrindfromthemanufacturingprocessisstoredattheplantandisreadilyavailable.WhileOtterProductsincorporatesrecycledmaterialscurrentlyintotheirdesign,thecompanyislookingtoincreasebothpercentages.

Someofthebiggestproblemsthatcanresultfromusingregrindare:blending,storage,andcolor.Manufacturingwithregrindcanbedifficultbecausethesizesofthegrainscanwidelyvarywithvirginandregroundmaterial.Thewiderangeofgrainsizescanleadtothematerialnotevenlymeltingwhichcanpotentiallycompromisematerialproperties.Anotherissuetobeawareofwhenusingregroundmaterialiswhereandhowitisbeingstored.Ifthematerialisstoredfortoolong,itcanabsorbmoistureanddustwhichcancontaminatethematerialnegativelyaffectingtheproperties.Colorisanimportantconsiderationwhenusingregrind.Brightercolors,suchaspink,showmanyissueswhentestingmaterials.Darkercolorsforthematerialwillbeutilizedtohelpavoidanycolorproblems.

Duetomaterialpropertiesbeingsignificantlylessenedbytheadditionofcolor,blackmaterialwaschosentouseforrecycling.Blackisthemostpopularcoloronthemarketandshowsthebestresultsduringmaterialtesting.Toelevatethelooksofablackcaseafewideashavebeenexploredtoaddvisualappealwithstillonlyusingrecycledmaterial.OneoptionthatwaslookedintowasIMLsor“inmoldlabeling.”Thismethodofdecorationusesapreprintedplasticlabelthatisinsertedintothatmoldbeforethatplasticisinjectedtomoldthecase.Thisoptiongivesmanypossibilitiesofhowthecasecouldlook,almostanydesigncanbeprintedtocreatetheIMLwhichleavesalotofdesignfreedom.ThebiggestdrawbackofusinganIMLismakingoneoutof100%recycledmaterial.IMLsaretypicallymadefromPP(polypropylene)orPC(polycarbonate)whichcanbotheasilyberecycledandreused.However,thecoloringinthelabelscreatesproblems.IMLsneedtobeprintedoneitherclearorwhiteplastictocreateaclearandvibrantimage,whichwouldbehardtoachieveusing100%recycledmaterials.AnotheroptionpresentedtouseinthecategoryofIMLsisusing100%recycledwood.Thisideaisbeingexplored,butisnottoofaralongintesting,sotimewiseitmightnotviablybeanoption.Anotherpossibilityisscreenprinting.Screenprintingisusedinmanymanufacturingprocessestoadddesignstoplasticsandothermaterials.Thistechniqueusesmeshtotransferinkontothedesiredsurface.Thisoptionworkswellwiththecommutercasebecausethereisalargeflatsurfaceareafortheprinttogoon.Withscreenprintingtheissueofusingrecycledmaterialwouldnotbeaproblem.Whiletherearemanyoptionstodecoratethecase,someoptionsmightbemorefeasible[4].

OtterProductsisabletocreatesuchdesignsbyusingstateofthearttechnology.OtterProductsstartseachprojectdesignwithdesigndata.Thezerosurfaceisusedtocreatemultipleoffsetsusingsolidworks.Theseoffsetsareusedasreferencesandtohelpbuildsurfaces.ThisassuresthattheTPEandPC

8DesignProblemAnalysisOtter Products ‘Green’ and Gold Case

alignperfectly.Withthismythology,thedesignersareabletobuildbeconstant,sinceeveryoneisusingthesameoffsetdistancesanddesigndata.Forexample,allcommutershavethesamenominalwallthicknessforboththeTPEandPC.

DesignProblemAnalysis

ThegoalofthisprojectwastodesignaninnovativeiPhone6scaseusingahigherpercentageofrecycledmaterials.ItisimportanttomaximizethepercentageofrecycledmaterialswhilestillholdingtheintegrityofOtterProduct’squalitycases.

CustomerandEnd-UserNeeds

OtterProduct’ssetsthestandardwhenitcomestodesigningastylishphonecasewithoptimalprotection.TheCommuterwasbuiltforefficiency.Thoughitisnottheirminimalistdesign,thecasemaintainsasleekprofilewhilebeingabletowithstandrigoroustesting.TheCommuterisdesignedfordropprotection,portprotection,easilyslippingintoapocket,andscratchprotection.ThetargetaudiencefortheCommuterisbusinessprofessionals,parents,andstudents.ThesecaseswillnotbesoldduetolegalityreasonswithOtterbox.

Objectives

Onthematerialsside,theteamwantedtomaximizethepercentageofregrindwithineachofthecasematerials.Thiswasthehighestprioritymaterialobjective.Oneofthemajorproblemswithusingregrindistheinabilitytoseparatecolorsbeforethepiecesareblendedandinjectionmolded.Costisalwaysaconcernforengineers.Withallofthesampletestingandmaterialpurchases,theteamwantedtominimizecostandstaywithinthe$4,500budget.Thelowestpriority-ratingobjectivewastomakethematerialbiodegradable.TheteamdidresearchtoseeifthiswasapossibilityanddiscussedtheoptionswithOtterProducts.ThematerialobjectivescanbeseeninTable1.

TABLE1:MATERIALOBJECTIVES

ObjectiveNamePriorityRating

MethodsOfMeasurements

ObjectiveDirection Target

RecycledMaterials

5 MaterialComposition(%) MaximizeTPE=100%

PC=100%

Cost 3FundsUsedToAcquire

MaterialsMinimize <$4,500

Biodegradable 2 Degrading Maximize 100%

9DesignProblemAnalysisOtter Products ‘Green’ and Gold Case

Thedroptestwasoneofthebiggestchallengesfacedbythenewdesign.Theimpactfromadropisthemostcommonwaytodamageaphone.ThecurrentstandardforanOtterProductscaseistowithstandthefallfromfourfeet.Theobjectiveofthisdesignwastoexceedthatstandard.ThecurrentCommuterphonecasehastwoplugstocoverthechargingoutletandtheheadphonejack.Byremovingtheseportplugs,itwillmakethedesignmoresleekanduser-friendly.Minimalwallthicknessisanotherdesignobjectiveforthenewcasedesign.Optimizingprotectionwhileminimizingthicknessisthegoalandthetargetistokeepthewallthicknessunder0.25inches.Toolingdesignwillensuretheproductismanufactureduniformlyandconsistently.Theobjectivewastokeepthetoolingdesignwithin0.01inchesoftheCADdrawing.Lastly,textureschemesonthepolycarbonatesurfacewouldliketobeaddedtothenewdesigninordertobothincreasegripandaesthetics.Table2illustratesthedesignobjectives.

TABLE2:DESIGNOBJECTIVES

DesignObjective PriorityRatingMethodOf

MeasurementsObjectiveDirection Target

DropProtection 5 Height(ft) Maximize >4Feet

RemovingPlugs 5 Visual Minimize <2Plugs

OutsideCaseTexture 5 Slope Maximize >15deg

WallThickness 5 Height(in) Minimize <0.25in

MeshBetweenTPE&PC

5 Angle(deg) Maximize 15deg<x<70deg

ToolingDesignTolerance

4 Inches Minimize ±0.01in

Aesthetics(GoldLettering)

4 Visual Maximize Present

ManufacturingCost 4 Dollars/Case Minimize <$35/Case

Weight 3 Grams Minimize <42.5g

Constraints

TheconstraintsforthematerialscomefromtheextensivetestingthatOtterProductsdoestoinsurequalityproducts.Mostimportantly,thisprojectistomakeacaseoutofrecycledmaterial,soitisessentialthatthematerialsusedtomakethecaseareahigherpercentageofrecycledmaterialsthan

10DesignProblemAnalysisOtter Products ‘Green’ and Gold Case

whatiscurrentlyallowedinthecasesalreadybeingmade.Next,thematerialneedstowithstandalltheabuseitwouldgothroughifitwereinthehandsofacustomer.Thematerialneedstoholditspropertiesthoughhighheat,extremecold,andsun.Itisalsoimportantthatthematerialdoesnoteasilywearwhenbeingabradedwithcanvas,bluejean,andotherobjectsitmightcomeincontactwith.Likewise,itneedstoresistallhouseholdchemicalsthataphonecasemighttouch.Last,thematerial’scolorneedstobefairlyconsistentsothatthereisnotawidevarietyofcolorscomingfromonespecificcasecolor.Thecolorchangefromchemical,abrasion,andconsistencywillbemeasuredwithaspectrophotometer.ThespectrophotometergivesavalueofΔE,whichissimplythedistancebetweentwocolors.Table3showsthematerialconstraints.

TABLE3:MATERIALCONSTRAINTS

ConstraintName MethodsOfMeasurement Limits

RecycledMaterials MaterialComposition(%)TPE>20%

PC>25%

HighTemp/HighHumidity Visual NoChange

ColdStorage Visual NoChange

ThermalShock Visual NoChange

Abrasion (1)Grams&(2)Visual (1)<0.05&(2)ΔE<2.3

BlueJeanAbrasion (1)Grams&(2)Visual (1)<0.05&(2)ΔE<2.3

CrossCutAdhesion Class ≥4B

UVA ΔE <2.3

UVB ΔE <2.3

Tensile/Elongation Length(in) NoChange

HouseholdChemicalResistance (1)Grams&(2)Visual (1)<0.05&(2)ΔE<2.3

TearTest Force(Lbf) NoChange

ResistancetoFlexing Inches Deflection<5%

ColorConsistency ΔE <2.3

TherearemultipledesignfeaturesoftheiPhone6swhichhavetobeincorporatedintothedesignofthecase.Themajorconstraintsincludethelength,widthandheightofthephone.Theseareimportanttoinsurethephonefitssnugglyinsidethedesignedphonecase.Inaddition,thephoneitself

11DesignSummaryOtter Products ‘Green’ and Gold Case

hasafewbuttons,camera,andspeakers,whichhastohaveproperlydesignedinsertsfor.Ifthesefeaturesarenotproperlydisplayed,thephonewilllosefunctionality.Sincethephonecaseisintendedtoprotectthephone,itcannotinhibititsfeaturesotherwiseconsumerswillchooseanotherproduct.ThedesignconstraintsareillustratedinTable4.

TABLE4:DESIGNCONSTRAINTS

DesignConstraints MethodOfMeasurements Limit

Thickness Inch >0.28Inch

Height Inch >5.44Inches

Width Inch >2.64Inches

CameraInsert Visual OriginalDesign

DropProtection Feet 4Feet

SpeakerOpenings Audio OriginalDesign

Buttons(Detent) Force <0.05lbf

Buttons(Activation) Force >4lbf

ScreenCover-Up Inch Display4.7inDiagonal

ManufacturingCost Dollars >$4,500

DesignSummary

OtterProductsseniordesignteamreinventedoneoftheircurrentproducts,theCommuterSeriesphonecase.Thenewcasecombinestwoseparatematerials,100%recycledTPEand100%recycledPCtomakeanouterandinnerprotectionofthecase.ThedesignwasstartedfromscratchbutfollowsthedesignstandardsfortheOtterBoxCommuterproductline.Themajordesignupdatesincluderemovingmaterialfromthebackofthecase,removingtheplugsonthebottomofthecaseandchangingthematerialmeshangles.InpreviousApplecases,the“apple”onthebackofthephonehasacorrespondingcutout.Theteamdecidedtoremovethiscutout.Thebottomplugsincludethespeaker,chargingport,andmuterockerontheiPhone6s.Thesewereremovedforeaseoftheuser.Thedifferentmeshangleswereintroducedforauniquedesignalongsidethedifferentanglesforviewingthescreenandbuttons.DesignhasallmajorcomponentsincorporatedintheCADmodelandfinalfilletsanddraftformoldingpurposesarebeingadded.Figure1illustratesthedesignmodifications.

12DesignDecisionsOtter Products ‘Green’ and Gold Case

FIGURE1:DESIGNMODIFICATIONSFROMOTTERPRODUCTSCOMMUTER(LEFT)TOSENIORDESIGNMODEL(RIGHT)

DesignDecisions

OtterProductshasamultitudeofdesignengineerswhoareresponsibleforkeepingupwithcurrenttrendsandnewdesignmodifications.ThedecisionstochangecertainaspectsofthecurrentCommuterwerediscussed,asshowninTable5.Theselectionswerechosenbasedonthebestoptionineachcategoryandthencombinedintothefinaldesign.ThematerialschosenaretherecycledPCandTPE.ThesematerialswerethemostconvenientandoneswhichdirectlyimpactOtterProducts.Weightreductionisacriticalcomponentsinceconsumerpreferthephonetobeaslightaspossible.Inthiscategory,thedesignteamtriedtoincorporateasmanyoptionsaspossible.Thecasewasmadethinner,tabswereremovedandafewribswerecutintothecasetomakeasthinaspossible.Intheend,thedesignteamconferredtochangethemeshanglesofthetwomaterials,takeouttheplugsandremovethecirclefortheApplelogo.

TABLE5:DESIGNDECISIONMATRIX

Option1 Option2 Option3 Option4 Option5

Recycled/GreenMaterial RecycledTPE RecycledPC RecycledAluminum Wood Recycled

Plastics

WeightReduction Lighter RibCutouts Thinner TabRemoval

13DesignDecisionsOtter Products ‘Green’ and Gold Case

Material

Aesthetics RemoveBackHole ColorVariety 2PieceFitting

PlacementStamp/Groove Texture

BetterProtection FoamInserts VariousShellTypes MaterialAdditives Fillet

Additions

ConceptSelectionToolingwasamajorpartofthisproject,andcouldbeawholeprojectallonitsown.Itwasthe

mostcostlyaspectaswellasthemostdifficult.Therewasalotthatgoesintothedesignoftooling,fromthegatingsystemtotherunnersandcavities.Onemajordecisionthathadtobemadeforthisprojectwastoeithermakeanewtoolortomodifyoldtooling.Producinganew,singlecavitytoolwouldbethemorecostlyoption,whereasmodifyinganoldtoolcouldsaveafewthousanddollars.Buildingarapidprototypetoolallowsforanynewdesigntobecreatedwithoutoverspending.Rapidprototypesareusedinindustrytotestnewproductsbeforecommittingtobuildingafourcavitytool.Asinglecavitytoolwasnotidealforproduction,howeversincethisprojectwassmallscaleitwasbeagoodoption.Therewasachoicetouseeitheranaluminumtoolorasteeltool,butthedecisionwasquicklymadetousesteel,duetopoorabilitytomanipulatealuminum.

Anotherdecisionthathadtobemadefortoolingwaslocation.Wasthetoolgoingtobemade

intheUnitedStates,orAsia?BuildingatoolintheUnitedStateswouldcutbackonshippingcostsaswellastimetoship.However,manufacturingcostsaremuchlowerinAsia.AfacilitythatOtterProductsuses,Broadway,locatedinChinawasthebestoptionfortheneedsofthisproject.Broadwaycanmakethetool,aswellasmoldtheparts.Theywereoneofthecheaperoptionsavailableforus.Timewasahugefactor,sothecasedesignCADwasgiventoBroadwayinJanuaryinordertogivetheteamenoughtimetogetthetoolbuiltbeforeMarch.ThetoolingdecisionmatrixisillustratedinTable6.

TABLE6:TOOLINGDECISIONMATRIX

Option1 Option2 Option3 Option4 Option5

Manufacturing CreatingNewTool

ModifyingOldTool

RapidPrototype

CreatingNewTool

RapidPrototype

Location Broadway Unique Sanmina Technimark CSU

ShippingCost China Singapore UnitedStates UnitedStates UnitedStates

ToolMaterial Steel Steel Steel Steel Aluminum

FinalConcept

Ourcasewasdesignedtoprotectfromtheeverydaywearandtear.Thephonewillbeabletowithstandimpact,chemical,environmentalandabrasiontesting.ThestrictdesignstandardsofprotectinganAppleiPhone6sdevicewerepreciselyfollowedtoensurethephoneproperlyfunctions.

14DesignDecisionsOtter Products ‘Green’ and Gold Case

OtterProductsCommuterdesignstandardswerealsomonitoredtomakesurethecasemeetsthesameprotectioncomparedtostandardCommuter.ThenewlyredesignedCommutermadefromrecycledOtterBoxcasessuccessfullymeetsOtterProductsstandardsforprotection.Thisnewphonecase,builtprimarilyformaterialsresearchpurposes,wasdesignedforpotentialcustomersinneedofasociallyresponsible,visuallyappealingandprotectiveproductthanmaintainsasleekprofilewhilebeingabletowithstandrigoroustesting.Intoday’ssociety,reduce,reuse,andrecyclehavebecomeapartofeverydaylife.

GeometricModeling

ThemaindesignforthephonecasewasgeometricallymodeledinSolidworks.Thisprogramallowsfortheflexibilitytoadaptthedesignandmakesmallmodifications.Inaddition,themodelcanbeadaptedto3DprintbycreatinganSTLfile.Thedesignwascomposedoftwodifferentmaterialsthatfittogetheraroundthephone.Thetotalthicknessofthedeviceis0.120inches.Thereisastandard0.05inchgapbetweenthetwomaterialstoallowforaproperfit.

ThedesignfeaturesstrictlyfollowthecasedesignguidelinesproposedbyApplefortheiPhone6s[5].Theguidelinesaresettoinsurethefunctionalityofthephone.Appleprovideskeepoutconestomakesurenopartofthecaseoverlapstheseareas.Thedesignalsoaccountsfordraftanglesforinjectionmoldingonallmajorcutouts.Inorderforaparttobeproperlyreleasedfromamold,angleshavetobeinfavorofeasilypullingapartfromthemoldthecasefromthetooling.

Thepolycarbonateoutershellallowsforasleekdesigntoprotecttheoutsideofthedevice.Draftanglesareappliedtoallopenings.Thelargestchallengewiththedesignwastomakesurenoneofthecutoutsatthebottomweretoothinwheretheywouldeasilycrackonimpact.ThethicknessofthePCis0.06inches.Figure2illustratesthepolycarbonateinpinkandthethermoplasticelastomeringrey.

TheTPEistheinnermostlayertoprotectthephone.Thismaterialisflexibletoeasilyfitaroundthephoneandprotectfromanyscratchesthatmayimpactthedevice.ThelargestdesignadvantageistohavetheTPEsurroundthephonescreentominimizedamagesforimpacttesting.HeretheindentionforthePCtobesnugwiththeTPEisshown.TheareathatisraisedisflushwiththethicknessofthePC.AdditionalfeaturesofthedeviceareshownascomparedtothePC.Thereisaholeforthemuterockerandaraisedareaforthevolumebuttoncontrolontheleftsideofphone.ThethinnestpartoftheTPEis0.055inchesforthethickestareasand0.120inchesforthethickestpart.

15DesignDecisionsOtter Products ‘Green’ and Gold Case

FIGURE2:INITIALGEOMETRICMODEL

TheangleofcontactforthephonetouchscreenandtheTPEsurroundingthedevicehastobelargerthan120deg.TheangleisshowninFigure3.Thisallowsfortheoptimumcontacttotouchedgesandcornersofthedevice.Whendesigningfortooling,thereisnoadditionaldraftanglesforthescreen.

FIGURE3:SCREENCONTACTANGLECADMODEL

Thehomebuttonisanotherareatostayclearof.Thebuttoncannotbecoveredupbyanymaterialandhastobeaccessiblefromanangle.Thehomebuttononthedeviceisvitalforusersandchallengedthecasetomakethelargestscreencutpossible.Thefrontfacingcameraandproximitysensorsatthetopofthedevicealsohadkeepoutareasbuttomakethecasecutoutsymmetricalfromthescreen,thebottomhomebuttonwasthecriticalarea.Thecutoutangleforthehomebuttonwasmade100degreesandwasincorporatedintothescreen.TheserequirementsareillustratedinFigure4[5].

FIGURE4:HOMEBUTTONKEEPOUTCONE[5]

16DesignDecisionsOtter Products ‘Green’ and Gold Case

Thecameraandflashcutouthasbelargeenoughforthecameraqualitynottobeaffected.Cameratestingisoneofthemostimportanttestofthecase.ApplerecommendsacamerainsertbesurroundedbyblackPCmaterialandavoidthekeepoutareas[5].Figure5displaysApplesguidelinesforthecamerahousing,flash,andcamerakeepoutareas.Thedesignforthecameraisacontinuationofthesidemeshinganglestocreateanedgyparallelogram.ThesmalledgeatthebottomofthePCis0.02inchestall.Thisisformoldingpurposes,materialcannotflowintotheseareasistheycometoapoint.

FIGURE5:CAMERACUTOUT

Lookingatthesideprofileofthephonecase,uniquemeshingangleswerecreatedtointerlockthePCwithTPE.Theanglesallowforahandtogriparoundthephoneandproduceastrongmeshingofthematerials.

PreliminaryTestingAnalysis

Inordertounderstandtherecycledmaterials,materialsquaresweremoldedandtestedpriortothefinaldesignwork.Thematerialsquaresweremoldedfrom100%recycledOtterBoxcases.ThepolycarbonateandthermoplasticelastomermaterialsquareswentthroughaseriesofOtterProductsstandardtrialsincludingenvironmental,abrasion,andchemicaldurabilitytests.Thesetestsweredoneforpreliminarymeasure.Ifthematerialsquaresseverelyfailed,itwouldbeobvioustonotcontinuewith100%recycledOtterBoxcasesforthematerial.

Figure6illustratesthePCmaterialstripsaftertesting.Thetestsamplesreactedverywelltotesting.Theabrasionaffectsarebarelyvisible.

17DesignDecisionsOtter Products ‘Green’ and Gold Case

FIGURE6:PCPOSTTESTING,(FROMTHELEFT)THERMAL,ABRASION,&CHEMICALTEST

TheTPEmaterialsamplesaftertestingareillustratedinFigure7.Therewereminorfailuresseenafterthesunscreenandabrasiontests.

FIGURE7:TPEPOSTTESTING,(FROMTHELEFT)THERMAL,ABRASION,&CHEMICALTEST

Thethermoplasticelastomerwentthroughamechanicaltestthatthepolycarbonatedidnotendureatthisstageintesting.AccordingtoASTMstandards,anelongationtestwasmeasuredtofindtheElasticModulusoftherecycledmaterial.ThisdataisillustratedinTable7.

18DesignDecisionsOtter Products ‘Green’ and Gold Case

TABLE7:TPEMECHANICALTESTINGDATA

Test Category SubcategoryAverageTensileYieldStress(psi)

AverageTensileYieldStrain(in)

AverageModulusofElasticity(psi)

ASTMD412Elongation Durability Mechanical 175.4 5.99 29.29

*Thesetestsweredonewithamaterialtemperatureof80°F.

TensamplesweretestedfortheASTMstandardtest,thesetrialsarepicturedinFigure8posttest.Theirtensileyieldstressandtensileyieldstrainwererecorded.Fromthisdata,eachsamplesmodulusofelasticitywascalculatedandaveraged.Therewaslittlevarianceinthisdata.Thestandarddeviationis0.33.

FIGURE8:TPEPOSTMECHANICALTESTING

Thefailuresthatwereseenwereminor.Duetothefeasibilityanalysis,thematerialsmovedontothedesignstage.

FailureModesandEffectsAnalysis

Ahighlevelanalysiswasdonefortheresultsoftheproject.ThefailuremodesandeffectsanalysisisshowninTable8.

TABLE8:FMEAANALYSIS

19DesignDecisionsOtter Products ‘Green’ and Gold Case

Function PerformanceStandards

FunctionalFailures

FailureModes FailureEffects Consequence

Category Rank

Providepropercameracutout

Noobstruction Obstruction Designerror

CustomerangrywithOtterProducts-

demandsnewphonecase/refund

OtterProductslosescustomer

trust4

Nostrayreflections

Strayreflections

Designerror

CustomerangrywithApple(believeitis

theirfault)-demandsnewphone

OtterProductsangersApple 3

SpecificShapeNotthespecificshape

Designerror

Protection

DropprotectionCasebreaks Material

properties

CustomerangrywithOtterProducts–demandsnewcase/refund

OtterProductslosescustomer

trust3

Phonebreaks Baddesign

ImpactresistantCasebreaks Material

Properties

Phonebreaks Baddesign

Environmentprotection

Button

Pushbutton

Obstruction Designerror

CustomerangrywithOtterProducts–

demandsnewphonecase/refund

OtterProductslosescustomer

trust4

Materialproperties

MaterialIssue

Easy

>4lbfactivationforce

Designerror OtterProducts

customertrus 2

<0.05detent

TABLE9:MITIGATIONPLANFORFMEA(OTTERPRODUCTSSTANDARDS)

Level Definition Action

4 CriticalFailure

Failureofakeymarketingclaimorcustomerrequirement.ORwilllikelydrivewarrantyreturns

Itwillberareforthistoproceed.Butifallowed,itwillrequire

20DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

abovethetargetmaximum.ORcausesdamagetotheconsumer’sdeviceorpreventsdevicefunctionality.

DirectorofGlobalProductQualityapprovalandcustomerwaivertomoveforward.

3 MajorFailure

Failureofacustomerrequirement.ORFailureisnoticeabletoconsumer.ORFailuremaydrivesignificantlyhigherthannormalwarrantyreturns.ORFailureimpedesbutdoesnotpreventfunctionality.ORFailureoccursfrequently.

RequiresDirectorofGlobalProductQualityapprovalorcustomerwaivertomoveforward.

2 ModerateFailure

Failuremightbenoticeabletoconsumers.ORFailuremightleadtoslightlyhigherthannormalreturnrate,butthatisunlikely.ORFailureoccursinfrequently.

Requiresdiscussionamongtechlead,designengineers,andqualityteamrepresentativestomoveforwardwithoutfixingtheissue.

1 MinorFailure

Failurefallsjustoutsideofpasscriteria.ORFailurewouldnotbenoticedbycustomer/consumer.ORFailuredoesnotaffectfunction.

Proceedwithdesign,butmonitoronfuturesamples.Makeimprovementsduringfutureprograms.

DetailedDesign&SupportingAnalysis

ThisnewcommuterphonecasehasamultilayerprotectiondesigntofitanAppleiPhone6/6s.Thisinnovativedesignincludeduniquecameracutout,meshinganglesbetweenthetwomaterials,uniquetexturesandpadprintingforittostandoutamongothercases.

Forthisdesigntobepossible,thephonecasewasmodeledusingadvancedsurfacinginSolidworkswithacentralizedsurfacemodelwhichallowedtheassemblytoeasilybemodified.ThedesignalsofollowedAppleandOtterProducts’designstandardstoensurethecasecouldeasilybemanufacturedandforthephoneusenottobecompromised.

Manydesignfeatureswereimplementedinordertoallowefficientmanufacturingprocess.Coringwasintroducedinordertopreventsinkinthethermoplasticmaterial,draftangleswerecreatedtoprovidesmoothreleasefromthesliders,andundercutissueswereaddressedtoallowproperfunctionofthetool.

Modeling&Analysis

OtterProductsdesignsmobilecasesusingveryadvancedsurfacingmodeling.Creatingamid-surfacebetweenthepolycarbonate(PC)andthermoplasticelastomer(TPE)allowsforchangestobemadeeffectivelyandefficientlyespeciallyifthereisachangetothemobiledeviceitself.Additionally,thecaseopenings,likefortheplugsandcamera,canbecreatedinthismid-surfaceforaccuratemeshingbetweenthetwomaterialsandforanypossiblechanges.Theseadjustmentshappeninthemid-surfaceandautomaticallypopulateinboththePCandTPEparts.

21DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

Whendesigningthecase,thereweresomerulesthatneededtobefollowedbothfromAppleandOtterProducts.Applehaskeep-outconeswherethecasecannotintrudeinthecone.Therearekeepoutconesforthecamera/flash,homebuttonandscreen.TherearedesignstandardsthatOtterProductsfollowsinordertoproduceasuccessfulcase.Forexample,whenitcomestodesigningthebuttonsOtterProductsoffersdistancesandthicknessesthataresuggestedformanufacturingasuccessfulbutton.

Afterthecasedesignwascompleted,theCADfilesaresubmittedforaCADreview.ThisCADreviewentailsamold-flow,draftangle,directionofpullandthicknessanalysis.OncetheCADwasapproved,itwassubmittedtothetoolingmanufacturer(Broadway)throughaDesignforManufacture(DFM).

FIGURE9:FINALDESIGNCHANGES

Manufacturability&AssemblyConsiderations

Forthecasetoproperlybemanufactured,therearemultipledesignconsiderationstoensureaflawlessmold.Casesaredesignedtobeinjectionmoldedwithplastic.AkeyfeaturewastomaintainnominalwallthicknessesthroughouttheTPE,whichpreventssinkinthematerial.Thisoccurswhentheouterlayerofplasticcoolsbeforeinside.Whenthematerialistoothick,thepartwillhavedifferentcoolingrates.Topreventthis,coringcutoutswereaddedaroundtheinsideedgeswheretheouterplasticdoesnotcovertheTPE.Detailedbelowisananalysisthatdiscussesareasthatneededimprovementsbecausethewallthicknesseswerelarge.TheTPEwallthicknesscorrectionsareillustratedinFigure10.

22DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

FIGURE10:TPEWALLTHICKNESSCORRECTIONS

AmoldflowanalysisinAutodeskwasperformedontheTPE.Theoutcomeshelpeddesigniterationinsuringpartqualityandtoolingmanufacturingcapabilities.Theanalysisshowedairtrapsandweldlinesinthematerial,whicharearoundtheportsandcamerabecausethesearethelastplacestheplasticfills.Aweldlineiscreatedwheretheplasticislasttofill.Ifthecaseisdropped,thisisthemostfragileregionbecauseoftheairtrapsandweldlinesintheseareas.

FIGURE11:AIRTRAPS(LEFT)SINKMARKS(RIGHT)

Theorientationattheskinprovidesagoodindicationofhowmoleculeswillbealignedwhenmolded.Thefibersisusefulforestimatingimpactstrength.Theimpactstrengthishigherinthedirection

23DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

ofthefibers.Thishelpedplacethegateofthepart.Havingthegateatthecenterhelpedorientatethefibersinthedirectionofimpactwhenacaseisdropped.Alsoshrinkageishigherinthedirectionoftheskin.Whenthemolecularorientationisconsistentwithnoturbulentflows,itleadstoahigherpartquality.

Figure12showsthatthegatelocationisinthemiddleofthecase.Thepurposeofthisisforplastictouniformlyflowatthesameratewiththesameviscosity.Weconsideredhavingthegateatthecamerahole,butthiswasdeclinedbecausebythetimetheplasticwouldhavereachedallthewaytotheplugopeningstheplasticwouldbemuchcoolercausingahighviscosity.Asaresult,thepartwouldrequiremorepressuretopushthishighviscosityplasticwhichinturncouldcausebiggerairpocketsandweldlinewhichasaresultputsthecaseatahigherfactureriskinthoseareas.ThereforetheteamchoosetoplacethegatefortheTPEinthemiddleofthepartforuniformplasticflow.Thepartstheoreticaltimetofillthecavityis0.602sandthecycletimeofthemachineforTPEis65sandforthePCis45s.ThetheoreticalpressuretofilltheTPEis2170psiattheinjectionsiteasseeninFigure12.

FIGURE12:TURBULENT/LAMINARFLOW(LEFT)PRESSURETOFILL(RIGHT)

Fortheouterplasticpart,thegateislocatedontheinsideacrossfromthestyleline.Iftherewereanyimperfectionsinmoldingthattransferredtotheotherside,thestylelinewouldhide.ItisnotanissuetogateoffcenterforthePCbecausePCisnaturallylessviscousthanTPEandeasiertomold.

TheTPEinjectionsiteislocatedatthecenterfortheTPE.Figure13(right)demonstrateswhatplasticleftoverinpink,aftermolding.Toremovethiscleanly,adiecutcirclepunchiscreated.Themoldflowanalysisdepictsitsanalysisbasedofftheinjectionsite.TheinjectionsiteandorientationisshowninFigure13.Figure13(left)showsthePCgatewhichiscalledacashewgate.Thistypeofgateisusedbecausethecaseeasilybreaksfreewhentheliftersandejectorpinsreleasethecaseoutofthetool.ThisisacleanbreakbecausePCisaharderplasticcomparedtotheTPE.

24DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

FIGURE13:INJECTIONORIENTATIONONPC(LEFT)INJECTIONSITEFORTPE(RIGHT)

Thepartinglineonapartisthecenterallthewayaroundthephone.ThishelpsdeterminewhichwaydraftanglesareimplementedbecausethisiswheretheAandBsideofthetoolmeettomakethemold.Anotherkeyconceptishowthepartwillberemovedfromthetool.Forthistohappen,draftanglesinthedirectionofthetoolhavetobeaccountedforofaminimalangleof3deg.Thisincludesalledges,coringandcutouts.Oncethepartiscooled,themovingsideretractsoutleavingtheparttoeasilyberemoved.ThePCpartinglineisshowninFigure14.

FIGURE14:PARTINGLINEOFTHEPC

Althoughthereweremanyaestheticdesignfeaturestheteamwouldhavelikedtomoveforwardwithinourpreliminarydesign,realworldapplicationrestrictedsomeoftheideas.ThefinaldesignmeshinganglesbetweenthePCandTPEwerechangedfroma65degreeacuteangletoa105degreeobtuseangleinordertopreventundercutinthetooling.Thiswastoensurethatthelifterandslidersdidnotcatchthepartandcauseittobreak.Additionallyavoidingundercutsensuresthattheliftersandslidersmovedoutofthewaybeforethetoolshutsinordertomakeanotherpart.Thesamechangeneededtobemadeinthecameracutout.Ourpreliminarydesignwasaparallelogrambutwas

25DetailedDesign&

SupportingAnalysisOtter Products ‘Green’ and Gold Case

modifiedtoatrapezoidtoavoidundercuttingthepart.ThemodifiedcameracutoutwiththelifterisillustratedinFigure15.

FIGURE15:MODIFIEDCAMERACUTOUTWITHLIFTER

Aminimumdraftangleof3to5degreeswasimposedonallsurfacesincontactwithslidersonthetoolInordertoensurethepartscouldbeejectedsmoothly.Inordertoproperlydrafttheseangles,theteamhadtounderstandwhichdirectionthesliderwouldbepullingawayfromthepart.ThedirectionofthesliderisillustratedinFigure16.Areasthatcameintocontactwiththisincludethemeshingzonesbetweenparts,cameracutouts,andthecutoutsforthespeaker,charger,andheadphonejack.

26FinalEvaluationOtter Products ‘Green’ and Gold Case

FIGURE16:TPEPARTSHOWINGDIRECTIONOFSLIDER

ProductionUnit-CostAnalysis

Currently,theprocessofobtainingandextrudingmaterialintopelletsisexpensive.However,ifthisprocesscouldbecompletedinhouse,thecostofmaterialwouldreduce.Therearealotofexcesscasesatmanufacturingfacilitiesanddistributioncentersonhand.Iftherewereawaytofacilitatethecollectionandproductionoftheseextracases,theproductionunit-costcouldbereduced.Realistically,OtterProductsmaynotbeabletohave100%recycledOtterBoxcasesineachoftheirproductionlinesduetomaterialonhand.However,withthedatacollected,OtterProductsunderstandstheyhavethecapabilitiestoincreasetheamountsofrecycledcasesintheirproduction.

FinalEvaluation

ManufacturingandAssembly

ThePCtoolsideB,showninFigure17,indicatesthelocationsofseveralkeycomponentsofthetool.SideBofthetoolisthemovingside.Thelifters,slider,andejectorpinsareshownbelow.Withthedesignconsiderationstakenintoaccountformanufacturing,thePCtoolwassuccessfulintheprototype

27FinalEvaluationOtter Products ‘Green’ and Gold Case

production.Thetoolwasmountedtoadollytable.ItwillbeusedforlearningpurposesatOtterProducts.

FIGURE17:RENDEREDCADOFPCTOOLSIDEB

Therewasoneproblemseenduringthemoldingprocess.TherecycledTPEwascausingthepresstosticktogether,whichwouldcreatealoudpoppingnoisewhenthemoldopened.Thisissuewasnotseenwiththevirginmaterialandmighthavebeencausedbytherecycledmaterialhavingaslightlyhighermelttemperature.Duringtherecyclingprocess,thepolymerchainsintheplasticbecomeshorter.Thentomeltthematerialdownafterwards,moreenergyisneedduetotheshorterpolymerchains.Thecasewasalsocreatingasuctionagainstthetoolduetothelighttexturethatwasusedinthedesign.ThisissuehasbeenencounteredbeforeatOtterProducts.Inordertofixthisissueinthefuture,aheaviertextureshouldbeappliedtothecaseinordertofixthe“sticking”problem.Forthisproject,aprototypetoolwasusedtomoldthecases,soitwasnotinthescopeoftheprojectorbudgettochangethetexture.Lessthan100casesweremade,sothestickingissuewasmanageablebyusingmoldreleaseandzincstearate.Zincstearate(soap)isanorganicmetalsalt-fattyacidthatisusedforreleasingplasticfromametalsurface.Itiscommonlyusedinamorphous,crystallineandsemicrystallineresins.Itcanalsobeusedasaresin“flowenhancer”atdifferentratiosbecauseitreducesfrictionallowingresinstheabilitytofloweasier.ThisisanidealsolutionbecauseitisalsoFDAapproved.Ifmassproductionwaspursuedwith100%recycledOtterBoxcases,itwouldbeimportanttoimprovethetexture.

28FinalEvaluationOtter Products ‘Green’ and Gold Case

TestingandRefinement

Therecycledcasewasputthroughthesame24+teststhatOtterProductsputsalltheirproductsthrough.Thebroadcategoriesincludeaseriesofdurability,compatibility,andenvironmentaltests.Intotal,theseteststakeover238hourstocomplete.

Therecycledmaterialshowedminorvisualfailureswhentestedforabrasionandchemical.Theinitialplanofactionwastolookintoincorporatinganadditivetohelpwiththesedurabilityissues.However,aftertestingthevirginmaterial,thesamefailureswereobserved.SinceOtterProductsmovesforwardwiththesefailures,theteamheldourcasetothesamestandards.

TABLE10:DURABILITYTESTINGDATA

Test Category Visual Δε ΔW(g) Result

UV-B Durability Pass 0.5 N/A Pass

UV-A Durability Pass 0.4 N/A Pass

HighTemperature&HighHumidity Durability Pass 0.2 N/A Pass

ColdStorage Durability Pass 0.4 N/A Pass

ThermalShock Durability Pass 0.3 N/A Pass

Cross-CutAdhesion Durability Pass N/A N/A Pass

CanvasAbrasion Durability Fail N/A 0.0 NoChange

BlueJeanAbrasion Durability Fail 2.0 0.02 NoChange

Chemical Durability Pass N/A N/A Pass

Drop Durability 4ftMILSTD Pass

PurseDrop Durability 100dropsat1m Pass

TABLE11:COMPATIBILITYTESTINGDATA

29FinalEvaluationOtter Products ‘Green’ and Gold Case

Test Category Criteria Result

Button Compatibility <4lbfactivation

>0.3detent Pass

Call Compatibility NoChange Pass

Camera Compatibility NoChange Pass

Sensors Compatibility Respond Pass

Thevariancesbetweenthevirginandrecycledplasticswereweighed.SignificantchangeswerenotedintheTPE.Tounderstandthesedifferences,theteamexaminedhowitreactedtoimpacttesting.ThedataacquiredfromthePendulumImpactTesterincludeenergyabsorbed,maximumforce,andbouncebackangle.ThesethreesetsofdatagohandinhandwiththeelasticityoftheTPE.Theenergyabsorbedandmaximumforceisacquiredthroughtheforcesensor,placedbehindthematerialsample.ThedataistransferredthroughtheLabVIEWapplicationandsettorecordvalues.Theenergyabsorbedismeasuredinpercentage.Themaximumforceismeasuredinpoundforce.Thebouncebackangle,however,inordertounderstandwillneedtobeevaluateddifferently.Thebouncebackangleismeasuredthrougharotaryencoderattachedtothestationarypartofthependulum.Theangleisthen

pluggedinto𝑒 = 1 − cos [(𝜋 ∗ 𝜃) 180]Equation1inordertocalculatetheCoefficientofRestitution.

𝑒 = 1 − cos [(𝜋 ∗ 𝜃) 180]Equation1

where𝜃=returnangleafterthefirstimpact,measuredindegrees.

TherecycledCoefficientofRestitutioncantheneasilybecomparedwiththevirginTPECoefficientofRestitution.

Throughthecalculation,itwasfoundthattherecycledTPEhadalowerCoefficientofRestitutionshowingthematerialismoreelastic.ThismeanstherecycledTPEabsorbsmoreenergythanitsvirgincounterpart.Essentially,lessforceistransferredthroughthephonecasetothephonethanthevirginTPE.Thisisanimprovement.

ProjectCostSummary

30FinalEvaluationOtter Products ‘Green’ and Gold Case

Overall,thisprojectincludedseveralelementsnotinitiallybudgetedfortheproject.ThelargestcostwenttoshippingthePCtoolfromChinatoColorado.Thiswasthebestlearningexperiencefortheteamtophysicallytellhowthepieceswereproduced.Alsoforthepiecestobemanufactured,therewasacostassociatedwiththetimeandmanhoursspentoperatingthemachineandproducingtheparts.ThefinalbudgetisallocatedinTable12:FinalBudget

TABLE12:FINALBUDGET

Description Cost

PrototypeMaterial $500.00

ShippingMaterial $556.75

Molding150PC&PadPrinting $960.00

Molding200TPE $810.00

BroadwayToolPreparation $1,300.00

ACE–ToolHardware $60.21

MetalDistributors $18.30

E-DaysSupplies(giveaways) $31.00

E-DayShirts $153.58

Total $4,389.84

Summary&ExplanationsforDeviationsfromOriginalPlan

Theoriginalplanwastodesign,fabricateandtestamobilephonecasemadeentirelyoutofunusedOtterBoxcases.Oneofourgoalsduringthedesignprocesswastopushthemanufacturinglimitssoourinitialdesignhadahugeundercut.However,afterthedecisionwasmadetoproduceanewsinglecavitytool,theteamwasadvisednottohavethisundercutinordertoavoidpotentialtooldamage.Thiswasofvitalfiscalconsiderationwiththehighcosttomakethesetools.Originally,OtterBoxsuggestedmaterialtestingonavarietyofdifferentratiosofvirginmaterialtorecycledmaterialcases.However,thisbroughtupmaterialandmanufacturingconcerns.Therefore,theteamdecidetoutilize100%recycledOtterBoxcasesforthematerial.AnewpartoftheprojectthatwasnotintheoriginalplanwasshippingtheouterplastictoolfromChinatoColoradoanddisassemblingthetool.Thisallowedustotrulyseeandunderstandingtheplasticinjectionmoldingprocess.

31Conclusions&

RecommendationsOtter Products ‘Green’ and Gold Case

Conclusions&Recommendations

Inthefuture,itwouldbeidealtoseethecasemakewithothercolorsofOtterBoxcases.ThiswouldbemoreofarealisticuseforOtterProducts,sinceobtainingonlyblackcasesaddstimeandcosttotheproject.Itwouldbeimportanttoseeinthecolorantinthecaseswouldcauseanddegradationinmaterialproperties,andifthemixingofcolorscouldbemadeintoamarketablecolor.

FutureRecommendations

Inconclusiontothe2015-2016seniordesignproject,manylessonsandskillsweredeveloped.ByE-Days,ourprojectwasasuccessandhadfunctionalphonecasestoproveit.Ourteamlearnedhowtotakeaconsumerproductfrominitialconcepttomassproduction.

Inaddition,theprojecthasmultipledesignconsiderationsforproperfitaroundtheiPhone6/6s.Althoughthesedevicesareagenerationapartthecasecanproperlyfitbothphones.Tomakesuretestingwentsmoothly,theteamallocatedtimetotestthematerialbeforeproducingitintocases.Oncematerialwasmadeintocases,therewereafewissueswhicharrivedpertainingtothemanufacturingoftheTPE.ThemajorcomplicationscausedtheTPEto“stick”thetool.Thiscanberesolvedbyapplyingmoldrelease,athickertextureonthesurfacetothetoolorbyusingzincstearate.

Inaddition,awoodIMLwouldbeuniquetotherecycledcasesinceitismadefrom100%repurposedwood.Althoughtheteamonlyhadtwotrialcases,thereareafewwaystoimprovetheresults.Thebestwaytoimprovethisistohaveafangateinsteadofacashewgateinordertodistributetheheattoawiderarea.Thecashewgatemadetheheatveryconcentratedtoasmallareacausingburningandairpockets.Thiswasanadditionaldesignfeaturethatwasnotessentialtotheproject'ssuccess,butcouldenhancetheecofriendlinessoftheproject.

ThelargestrecommendationforfutureprojectswithinOtterProductsorwithanotherlargercompaniesistoprovidetheteamessentialssotheycanbeproductiveoutsideofbusinesshours.ThisprojectwouldnothavemadethehugeprogressitdidwithoutthetwointernsofOtterProductswhichwereapartoftheseniordesignteamandtheiraccesstocomputers.ThismadeitextremelydifficulttodelegatetaskstomembersnotemployedatOtterProducts.

32ReferencesOtter Products ‘Green’ and Gold Case

References

[1]'AboutOtterBox:OurStory//OtterBox.com',2015.[Online].Available:

http://www.otterbox.com/en-us/our-story.html.[Accessed:06-Sep-2015].

[2]“InjectionMolding:AnotherWaytoDealwithRegrind:PlasticsTechnology,”[Online]Available:

http://www.ptonline.com/columns/injection-molding-another-way-to-deal-with-regrind.

[3]T.Womer,'InjectionMoldingVirginvs.Regrind:PlasticsTechnology',Ptonline.com,2012.[Online].

Available:http://www.ptonline.com/tips/post/injection-molding-virgin-vs-regrind.

[4]J.PutkaandCSUOtterProductsTeam,“OtterProductsIntel,”Jan-2015.

[5]Appleinc,AppleDesignGuidelinesforAppleDevices,Vol.R10,pp.1-22,9-10-2015.

https://developer.apple.com/cases/Case-Design-Guidelines.pdf.[AccessedSeptember15,2015]

[6]Glstpes.com,'GLSThermoplasticElastomerDataSheet:DynaflexTMG2701-1000-02Thermoplastic

Elastomer',2015.[Online].Available:http://www.glstpes.com/product_search_datasheets.php.

[Accessed:26-Sep-2015].

[7]‘MAKROLONA®2405,2407and2456:PolycarbonateResins',2007.[Online].Available:

http://www.ledil.com/sites/default/files/Documents/Technical/Material/PC%20Makrol

on%202405_2407_2456-Datasheet.pdf.[Accessed:26-Sep-2015].

33AppendixOtter Products ‘Green’ and Gold Case

Appendix

FIGURE18:TPEDATASHEET[6]

34AppendixOtter Products ‘Green’ and Gold Case

FIGURE19:PCDATASHEET[7]

TABLE13:IMPACTTESTINGDATA-ENERGYABSORPTION

SimulatedHeight(ft) TPE EnergyAbsorbed[%] Difference[%]

35AppendixOtter Products ‘Green’ and Gold Case

3 Recycled 98.27

0.751 Virgin 97.51

4 Recycled 98.60

0.564 Virgin 98.04

5 Recycled 99.01

0.364 Virgin 98.65

6 Recycled 99.36

0.306 Virgin 99.05

TABLE14:IMPACTTESTINGDATA-MAXIMUMFORCE

SimulatedHeight(ft) TPE MaximumForce[lbf] Difference[lbf]

3 Recycled 1492.53

225.99 Virgin 1718.53

4 Recycled 1550.43

284.36 Virgin 1834.78

5 Recycled 1536.40

356.90 Virgin 1893.30

6 Recycled 1559.34

393.49 Virgin 1952.84

36AppendixOtter Products ‘Green’ and Gold Case

TABLE15:COEFFICIENTOFRESTITUTION,E,FORVIRGINTPE

SimulatedHeight[ft] Bounce-backθ[deg] CoefficientofRestitution

3 11.8 0.15

4 9.9 0.12

5 7.9 0.10

6 7.5 0.09

TABLE16:COEFFICIENTOFRESTITUTION,E,FORRECYCLEDTPE

SimulatedHeight[ft] Bounce-backθ[deg] CoefficientofRestitution

3 9.8 0.12

4 8.3 0.10

5 6.4 0.08

6 6.0 0.07

37AppendixOtter Products ‘Green’ and Gold Case

FIGURE20:OVERLAYOFCOEFFICIENTOFRESTITUTIONFORVIRGINANDRECYCLEDTPE