Thepowerofdesignforassembly

ByStephenKnowles,ManagingDirector,IDC

AtIDC,we’vehadafewprojectsrecentlywheredesignforassemblyhasbeenthecritical

factorindevelopingthenextgenerationofproductsforclients.Withthisinmind,weasked

IDC’sMD,StephenKnowles,toadviseabouthowtoachievethebestsolutionsandgivesome

toptips.

Q:Whyisdesignforassemblysoimportant?

A:“Designforassemblyisimportantbecausealargeproportionoftheproduct’scostisin

manufacturing.Productionandassemblycanbetimeconsuming,andequally,itcanleadto

qualityproblemsiftheassemblyprocessiscomplicatedwithtoomanysteps.Inshort-ithas

potentialtogowrongifnotproperlyplannedandtested!

Partoftheproductdesignprocessistodefinetherequirementsoftheproduct-it’snotjust

visual,it’smanufacturingmethods,volumes,costs,qualityandreliability.Byplanning

manufacturingrightatbeginning,alongsidefunctionalengineering,youcanensurethatyour

designisgoingtofulfilthecriteria.Assemblyrequirementsshouldbeintheproduct

requirementspecificationandyoushouldaimtomakeassemblyprocessesassimpleand

foolproofaspossible.”

Q:Sowhatarethebenefits?

A:“Reducedproductcostsandimprovedreliabilityarethetwobiggains.Therecanalsobe

benefitsofsustainabilitytooasyou'renotnecessarilyjustdesigningforassembly,butoften

you'redesigningfordisassembly,serviceandforreuse-whichmustbeconsideredatthesame

time.Sustainabilitycanbearealadvantagetoaproductinbeingabletokeepitgoingfor

longerandmakingitsuitableforrepairandmaintenance.”

Thepowerofdesignforassembly

Q:Wheredoyoustartasaproductdesignerwhenyouarelookingatsimplifyingaprocess

forassembly?

A:“Wellyoustartbyworkingoutwhattherequirementsfortheproductare.Forexample,ifit

isalowcosthighvolumemassmarketdeviceyou’dbelookingforreliable,lowcostassembly.In

thiscaseit’ssometimesaboutdesigningforautomatedassembly,notjustthinkingaboutthe

assemblyprocess,butdesigningsothattheseprocessescanactuallybeautomated.Thenit’s

integratingfeaturesintopartsthatcanbealignedbymachine.Designersneedtodesign

features(suchassnaporribfeaturesforcorrectpositioning)tosimplifyassemblyandmake

partsasself-aligningaspossible.Thisisthelevelofdetailthatneedstobeappliedtoensurethe

bestsolutions-anditbecomessotechnicalthatit’saspecialistdisciplineinitself!

Attheotherendofthescaleyou’vegotthehighvalueequipmentsuchaslaboratory

instruments,thataremadeinrelativelylownumbers,butoftenincludeelectricalandprecision

componentsthatneedtobeputtogetherbyhand.Theseareoftenpackedintoarelatively

smallspace,soit’simportanttounderstandtheorderinwhichthingsfittogether,andhow

easilytheyfitintothehousing.Thefixingsarealsoimportant-ifyou’vegottogetthescrews

intothebottomofthehole,canyougetaccesstoitormighttherebeabettersolution?

It'softengoodtotryandmaketheassemblyasmodularaspossiblesothatmuchofthe

assemblyhappensawayfromthemainbodyoftheproduct.Thismeansyoucouldassemble

oneparticularmodulewithlotsofspacearounditandthenassembleanothermodulewiththe

firstmodulesothatthesetwomodulessimplygetslottedintothemainproduct.Thiscanhelp

greatlywiththeassemblyprocessandcanalsobenefitservicingandmaintenance,becauseif

youhaveaproblemwiththemachine,theserviceengineercanquicklyswitchmodulesfor

repairandthenrepairthefaultymodulebackattheirworkshop.Sometimestheendusercan

takethemoduleoutsothatmanufacturerscanjustshipanewparttothecustomer,saving

moretimeandexpense.Modularproductscanbereallyusefulforkeepingmaintenancecosts

lowandsustainable.”

Q:Isresearchimportantwhendesigningforassembly?

A:“Yes,whenestablishingtheproductrequirementspecificationatthebeginningweneeda

thoroughunderstandingofmanufacturingvolumerequirements,assemblylocation,theskillsof

thepeoplemakingitandtheassemblyprocessitself.Obviouslythetargetcostisabigfactor

anywaysothattellsyouhowmuchtimecanbeallowedforthesekindofassemblyprocesses.

Weworkcloselywithclientstounderstandtheprocessinside-out-wewillgoonsite,speakto

staffontheproductionlineandthoroughlyunderstandhowwecanrefineandimprovethe

designtosimplifyassembly,improvequality,savetimeandcutcosts.”

Q:Howdoesqualitycomeintotheprocess?

A:"Qualitycomesintothisprocessthroughout.Whenwedevelopaproductwewouldtypically

doadesignFMEA(FailureModesandEffectsAnalysis).Thenwecanalso,withthe

manufacturer,doaprocessFMEAwhichislookingattheprocessesandwhatcouldgowrong.If

youwerejustlookingatthedesign,you’dlookatallthecomponentsandyou’dlookatallthe

waysinwhichtheycouldfailandobviouslyhowtheycouldpotentiallybemisassembledtoo.

Whenproductsarehandassembled,weneedtoensurethattheyareassembledexactlythe

sameeverytimebecausethereliabilityandsafetyofadevicedependsuponitbeingrightand

thisisverymuchaqualityissue.Sothenwearethinkingaboutthatdesignfromamanualpoint

ofview.Wearethinkingaboutwhatjigsandfixtureswouldbenecessarytofacilitaterepeatable

andreliableassemblyprocesses.

WhenwedevelopedtheAPAdvanceVideoLaryngoscopeforVenner,weactually

manufacturedthefirstfiftyunitshereatIDC.Intheprocessofdoingthis,wemanufactureda

numberofjigsthatwouldhelpholdthePCBintherightpositionwhilecertainpartswerefitted.

Jigsandfixturescanbeagoodwayofmakingmanufacturingpreciseandefficient.Jigsarebits

ofspecialistequipment,designedspecificallytodoacertainjobthatwillhelptheassemblingof

theparts.

Toensurequalityandreliabilityduringtheactualassemblyprocess,therearecommondesign

tricksyoucanuse.Forexample,poka-yokescanbeused,whichareanytypeofmechanismto

helpanoperatoravoidmistakeswhenassemblingcomponents.Theyaredesignedtoeliminate

misassemblybypreventing,correctingordrawingattentiontoerrorsaspartsareassembled.

Apoka-yokecouldbeaddedtoacomponentwhichlookslikeitisbasicallysymmetricalor

round,butbyaddingafeature,theoperatorcanrecognisethecorrectpositionforittobefitted

anditcannotbefittedinanyotherorientation.

Alternativelyitmaybepossibletodeliberatelydesignpartstobesymmetrical,soalignment

doesn'tmatter.Thiscanbereallyusefulinspeedinguptheassemblyprocess.Allowinglead-ins

intoholesandshaftscanbehelpful,sothatifsomethingisaclosefitbeforeitgetstothetight

stagethere'sanopeningthatactuallychannelsandself-alignsthecomponentbeforeit'spushed

intight.

Sothinkingaboutthewaythatthingscangowrongandactuallyanticipatingtheseinthe

designisakeyprinciple.Prototypingisalsoanessentialstagewhendesigningforassembly.It

meansthatdesignersgettoassembletheproductsinthedesignstageandinbuildingthe

prototypeyouunderstandsomeofthedifficultiesthatarelikelytobeexperiencedbythe

peopleonthemanufacturingline.Prototypingmeansthatthedesignandassemblycanbe

refinedandtestedtofindtheoptimumsolution.Atthetransfertomanufacturingstage,we

oftenmakejigsfortrials,aswellasmodellingtheassemblyprocessforlateron.”

Q:What’stheimpactofreducingcomponentsandassemblysteps?

A:“Ifyoucangetoneparttoperformmultiplejobs,younotonlyreducethenumberofpartsbut

alsoreducetheamountofassemblyworkandreducethepossibilityofmisassemblytoo.

Sometimesyoucangetcomponentsreducedbycombiningstructuralpartsusinginjection

moulding.

WeworkedonaprojecttodevelopanewlightingproductforStrand–theoriginalproducthad

49components,whichincludedtimeconsumingpartsthathadtobefittedtogetherwith

numerousscrews.Apriorityoftheprojectwastoreducethenumberofcomponentstospeed

upmanufacture.Bylookingatwaysofintegratingpartsusinginjectionmoulding,theteamwas

abletoreducethecomponentcounttojust17pieces.Assemblytimewasdramaticallyreduced

andqualitydefectsdecreased.”

Q:Issimplicitybest?

A:“Forthemajorityofprojects,simplificationofcomponentsisthebestwayforwardwhen

designingformanufacture.Fewerpartsmeanslesstime,andlessopportunityforthingstogo

wrongduringassembly,butthisisnotalwayspossiblewithincrediblycomplexdeviceswhich

justcan'tbesimplified.It’stheidealprinciplethough.Inthesecases,assemblysolutionssuchas

jigsandfixturescanhelpspeeduptheassemblyprocessandensurequality.Prototypingand

testingtheproductionprocessisessentialtounderstandwhatimpactdifferentsolutionshave.”

TopFiveTipswhenDesigningforAssembly

1. Thinkaboutmanufacturingandassemblyrightatthestart.Itmustbepartofthedesign

process,alongsidevisualanduserneeds.

2. Understandthevolumesandnatureoftheproductandassemblyrequirements.Isit

highvolume,singleuseorwillmaintenanceandrepairbeneeded?

3. Thinkaboutwhatcouldgowronganddesigntoavoidit.Howcouldcarelessassembly

causeproblems?Byanticipatingproblems,it’spossibletodesignsolutionstoavoid

misassembly.

4. Prototype&testtheassemblyprocesstocheckandrefinetheassembly.

5. Liaisewithmanufacturersaseachonehasdifferentpreferencesandskillsetc.

www.idc.uk.com

www.idc.uk.comt:+44(0)1753547610e:contact@idc.uk.comIndustrialDesignConsultancy,ThePortlandBusinessCentre,ManorHouseLane,Datchet,Berkshire,SL39EG,UK.