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‘Green’&GoldCase
OtterProducts
ColoradoStateUniversity
MechanicalEngineeringSeniorDesign
2015-2016
FinalReport
April28,2016
Team:
JulieCox:[email protected] ______________________________
AlexHeape:[email protected] _____________________________
KristenOssolinski:[email protected] ______________________________
CorinnePellish:[email protected] ______________________________
AmandaWilson:[email protected] ______________________________
OtterProductsAdvisor:
JeremyPutka:[email protected] ______________________________
CSUAdvisor:
Dr.MitchellStansloski:[email protected] ______________________________
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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
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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
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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
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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.
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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
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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
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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
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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%
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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
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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
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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.
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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
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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.
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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.
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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]
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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.
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17DesignDecisionsOtter Products ‘Green’ and Gold Case
FIGURE6:PCPOSTTESTING,(FROMTHELEFT)THERMAL,ABRASION,&CHEMICALTEST
TheTPEmaterialsamplesaftertestingareillustratedinFigure7.Therewereminorfailuresseenafterthesunscreenandabrasiontests.
FIGURE7:TPEPOSTTESTING,(FROMTHELEFT)THERMAL,ABRASION,&CHEMICALTEST
Thethermoplasticelastomerwentthroughamechanicaltestthatthepolycarbonatedidnotendureatthisstageintesting.AccordingtoASTMstandards,anelongationtestwasmeasuredtofindtheElasticModulusoftherecycledmaterial.ThisdataisillustratedinTable7.
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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
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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
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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.
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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.
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22DetailedDesign&
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FIGURE10:TPEWALLTHICKNESSCORRECTIONS
AmoldflowanalysisinAutodeskwasperformedontheTPE.Theoutcomeshelpeddesigniterationinsuringpartqualityandtoolingmanufacturingcapabilities.Theanalysisshowedairtrapsandweldlinesinthematerial,whicharearoundtheportsandcamerabecausethesearethelastplacestheplasticfills.Aweldlineiscreatedwheretheplasticislasttofill.Ifthecaseisdropped,thisisthemostfragileregionbecauseoftheairtrapsandweldlinesintheseareas.
FIGURE11:AIRTRAPS(LEFT)SINKMARKS(RIGHT)
Theorientationattheskinprovidesagoodindicationofhowmoleculeswillbealignedwhenmolded.Thefibersisusefulforestimatingimpactstrength.Theimpactstrengthishigherinthedirection
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23DetailedDesign&
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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.
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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
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25DetailedDesign&
SupportingAnalysisOtter Products ‘Green’ and Gold Case
modifiedtoatrapezoidtoavoidundercuttingthepart.ThemodifiedcameracutoutwiththelifterisillustratedinFigure15.
FIGURE15:MODIFIEDCAMERACUTOUTWITHLIFTER
Aminimumdraftangleof3to5degreeswasimposedonallsurfacesincontactwithslidersonthetoolInordertoensurethepartscouldbeejectedsmoothly.Inordertoproperlydrafttheseangles,theteamhadtounderstandwhichdirectionthesliderwouldbepullingawayfromthepart.ThedirectionofthesliderisillustratedinFigure16.Areasthatcameintocontactwiththisincludethemeshingzonesbetweenparts,cameracutouts,andthecutoutsforthespeaker,charger,andheadphonejack.
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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
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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.
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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
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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
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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.
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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.
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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].
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33AppendixOtter Products ‘Green’ and Gold Case
Appendix
FIGURE18:TPEDATASHEET[6]
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34AppendixOtter Products ‘Green’ and Gold Case
FIGURE19:PCDATASHEET[7]
TABLE13:IMPACTTESTINGDATA-ENERGYABSORPTION
SimulatedHeight(ft) TPE EnergyAbsorbed[%] Difference[%]
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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
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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
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37AppendixOtter Products ‘Green’ and Gold Case
FIGURE20:OVERLAYOFCOEFFICIENTOFRESTITUTIONFORVIRGINANDRECYCLEDTPE