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willreducethecostandtimeofthedesign,manufacturingand
assemblyofmechanicalconveyorsystemsusedinthefoodand
beverageindustry.Theimprovedmethodologyfordesignand
productionofconveyorcomponentsisbasedontheminimisa-
tionofmaterials,partsandcosts,usingtherulesofdesignfor
manufactureanddesignforassembly.Resultsobtainedonatest
conveyorsystemverifythebenefitsofusingtheimprovedtech-
niques.Theoverallmaterialcostwasreducedby19%andthe
overallassemblycostwasreducedby20%comparedtoconven-
tionalmethods.
KeywordsAssembly·
Costreduction·
Design·
DFA·
DFM·
Mechanicalconveyor
1Introduction
Conveyorsystemsusedinthefoodandbeverageindustryare
highlyautomatedcustommadestructuresconsistingofalarge
numberofpartsanddesignedtocarryproductssuchasfood
cartons,drinkbottlesandcansinfastproductionandassembly
lines.Mostoftheprocessingandpackagingoffoodanddrinkin-
volvecontinuousoperationswherecartons,bottlesorcansarere-
quiredtomoveatacontrolledspeedforfillingorassemblyoper-
ations.Theiroperationsrequirehighlyefficientandreliableme-
chanicalconveyors,whichrangefromoverheadtypestofloor-
mountedtypesofchain,rollerorbeltdrivenconveyorsystems.
Inrecentyears,immensepressurefromclientsforlowcost
butefficientmechanicalconveyorsystemshaspushedcon-
veyormanufacturerstoreviewtheircurrentdesignandassembly
methodsandlookatanalternativemeanstomanufacturemore
economicalandreliableconveyorsfortheirclients.Atpresent,
S.H.Masood(u)·
IndustrialResearchInstituteSwinburne,
SwinburneUniversityofTechnology,
Hawthorn,Melbourne3122,Australia
E-mail:
****************.au
mostmaterialhandlingdevices,bothhardwareandsoftware,are
highlyspecialised,inflexibleandcostlytoconfigure,installand
maintain[1].Conveyorsarefixedintermsoftheirlocationsand
theconveyorbeltsaccordingtotheirsynchronisedspeeds,mak-
inganychangeoveroftheconveyorsystemverydifficultandex-
pensive.Intoday’sradicallychangingindustrialmarkets,thereis
aneedtoimplementanewmanufacturingstrategy,anewsystem
operationalconceptandanewsystemcontrolsoftwareandhard-
waredevelopmentconcept,thatcanbeappliedtothedesignof
anewgenerationofopen,flexiblematerialhandlingsystems[2].
HoandRanky[3]proposedanewmodularandreconfigurable
2Dand3Dconveyorsystem,whichencompassesanopenre-
configurablesoftwarearchitecturebasedontheCIM-OSA(open
systemarchitecture)model.Itisnotedthattheresearchinthe
areaofimprovementofconveyorsystemsusedinbeveragein-
dustryisverylimited.Mostofthepublishedresearchisdirected
towardsimprovingtheoperationsofconveyorsystemsandinte-
grationofsystemtohighlysophisticatedsoftwareandhardware.
Thispaperpresentsaresearchinvestigationaimedatim-
provingthecurrenttechniquesandpracticesusedinthede-
sign,manufacturingandassemblyoffloormountedtypechain
drivenmechanicalconveyorsinordertoreducethemanufactur-
ingleadtimeandcostforsuchconveyors.Applyingthecon-
ceptofconcurrentengineeringandtheprinciplesofdesignfor
manufacturinganddesignforassembly[4,5],severalcritical
conveyorpartswereinvestigatedfortheirfunctionality,material
suitability,strengthcriterion,costandeaseofassemblyinthe
overallconveyorsystem.Thecriticalpartsweremodifiedand
redesignedwithnewshapeandgeometry,andsomewithnew
materials.Theimproveddesignmethodsandthefunctionalityof
newconveyorpartswereverifiedandtestedonanewtestcon-
veyorsystemdesigned,manufacturedandassembledusingthe
newimprovedparts.
2Designformanufacturingandassembly(DFMA)
Inrecentyears,researchintheareaofdesignformanufacturing
andassemblyhasbecomeveryusefulforindustriesthatarecon-
552
sideringimprovingtheirfacilitiesandmanufacturingmethodol-
ogy.However,therehasnotbeenenoughworkdoneinthearea
ofdesignforconveyorcomponents,especiallyrelatedtotheis-
sueofincreasingnumbersofdrawingdataandre-engineering
oftheprocessofconveyordesignbasedontraditionalmethods.
·
Emphasisestandardisation
Usethesimplestpossibleoperations
Useoperationsofknowncapability
Minimisesetupsandinterventions
Undertakeengineeringchangesinbatches
Avastamountofpapershavebeenpublishedthathaveinvesti-
gatedissuesrelatedtoDFMAandappliedtovariousmethodolo-
giestoachieveresultsthatprovedeconomical,efficientandcost
effectiveforthecompaniesunderinvestigation.
ThemainclassificationsofDFMAknowledgecanbeiden-
tifiedas
(1)Generalguidelines,
(2)Company-specificbestprac-
ticeor(3)Processandorresource-specificconstraints.General
guidelinesrefertogenerallyapplicablerules-of-thumb,relat-
ingtoamanufacturingdomainofwhichthedesignershould
beaware.ThefollowinglisthasbeencompiledforDFM
guidelines[6].
Thesedesignguidelinesshouldbethoughtofas“optimal
suggestions”.Theytypicallywillresultinahigh-quality,low-
cost,andmanufacturabledesign.Occasionallycompromises
mustbemade,ofcourse.Inthesecases,ifaguidelinegoes
againstamarketingorperformancerequirement,thenextbest
alternativeshouldbeselected[7].
Company-specificbestpracticereferstothein-housedesign
rulesacompanydevelops,usuallyoveralongperiodoftime,and
whichthedesignerisexpectedtoadhereto.Thesedesignrules
areidentifiedbythecompanyascontributingtoimprovedquality
andefficiencybyrecognisingtheoverallrelationshipsbetween
Designforaminimumnumberofparts
Developamodulardesign
Minimisepartvariations
Designpartstobemultifunctional
Designpartsformultiuse
Designpartsforeaseoffabrication
Avoidseparatefasteners
Maximisecompliance:
designforeaseofassembly
Minimisehandling:
designforhandlingpresentation
Evaluateassemblymethods
Eliminateadjustments
Avoidflexiblecomponents:
theyaredifficulttohandle
Usepartsofknowncapability
Allowformaximumintoleranceofparts
Useknownandprovenvendorsandsuppliers
Usepartsatderatedvalueswithnomarginaloverstress
Minimisesubassemblies
particularprocessesanddesigndecisions.Companiesusesuch
guidelinesaspartofthetraininggiventodesignersofproducts
requiringsignificantamountsofmanualassemblyormainte-
nance.Notethatmostofthemethodologiesaregoodateither
beingquickandeasytostartorbeingmoreformalandquanti-
tative.Forexample,guidelinesbyBoothroydandDewhurst[8]
onDFAareconsideredasbeingquantitativeandsystematic.
WhereastheDFMguidelines,whicharemerelyrulesofthumb
derivedfromexperiencedprofessionals,aremorequalitativeand
lessformal[9].
3Conventionalconveyorsystemdesign
Designandmanufacturingofconveyorsystemsisaverycom-
plexandtime-consumingprocess.Aseveryconveyorsystemis
acustom-madeproduct,eachprojectvariesfromeveryother
projectintermsofsize,productandlayout.Thesystemdesign
Fig.1.Layoutofconveyorsys-
temforlabellingplasicbottles
553
isbasedonclientrequirementsandproductspecifications.More-
over,thesystemlayouthastofitinthespaceprovidedbythe
company.Theprocessofdesigningalayoutforaconveyorsys-
teminvolverevisionsandcouldtakefromdaystomonthsorin
someinstancesyears.Onewiththeminimumcostandmaximum
clientsuitabilityismostlikelytogetapproval.
Figure1showsaschematiclayoutofatypicalconveyor
systeminstalledinaproductionlineusedforlabellingof
plasticbottles.Differentsectionsoftheconveyorsystemare
identifiedbyspecifictechnicalnames,whicharecommonly
usedinsimilarindustrialapplication.The“singlizer”sec-
tionenablestheproducttoformintoonelanefrommultiple
lanes.The“slowdowntable”reducesthespeedofproduct
onceitexitsfromfiller,labeller,etc.The“massflow”sec-
tionisusedtokeepupwithhigh-speedprocess,e.g.,filler,
labeller,etc.The“transfertable”transfersthedirectionofprod-
uctflow.Thepurposeofthesedifferentconveyorsectionsis
thustocontroltheproductflowthroughdifferentprocessing
machines.
Atypicalmechanicalconveyorsystemusedinfoodandbev-
erageapplicationsconsistsofovertwohundredmechanicaland
electricalpartsdependingonthesizeofthesystem.Someof
thecommonbutessentialcomponentsthatcouldbestandard-
isedandaccumulatedintofamiliesoftheconveyorsystemare
sideframes,spacerbars,endplates,coverplates,insidebend
plates,outsidebendplates,bendtracksandshafts(drive,tailand
slave).Thesizeandquantityofthesepartsvaryaccordingtothe
lengthofconveyorsectionsandnumberoftrackscorrespond-
ingtothewidthandtypesofchainsrequired.Theproblemsand
shortcomingsinthecurrentdesign,manufacturingandassembly
ofmechanicalconveyorsarevaried,butinclude:
4Areasofimpr