1、GroupTechnologyGrouptechnology(GT)isaveryimportantmethodologyintodaysmanufacturingsignificant/Thereasonforthisisthatgrouptechnology/whenutilizedtoitsfullestextent/canaffectmostareasofmanufacturing/includingdesign/processplanning/scheduling/routing/factorylayout/procurement/qualityassurance/machineto
2、olutilization/tooldesign/producibilityengineering/andassembly/1IntroductionGrouptechnologyisasimpleconceptthatisusedwidelyinvariousforms/Foravarietyofreasons/itislogicaltocollectandassociatethingsbasedonfeaturesthattheyhaveincommon/Thisapproachisfamiliartoeveryoneforplants/animals/andchemicals/Sucho
3、rganizationalstructureshavealsobeenusedforhardwareandotherobviouslysimilarproductswithinthemanufacturingworld/Grouptechnologyrepresentsstructuredcategorizationofparticularvaluetothemanufacturingcommunity/Itisalreadywidelyused；perhaps50%ofmanufacturingcompaniesusesomeformofGT/Bathorlotproductionsuffe
4、rsfrommanyinefficienciesduetopartvarietyandthegeneral-purposenature(flexibilityrequirements)ofmachinetoolsinuseontheshopfloor/Infact/aCincinnatiMilacronstudyshowedthat95%ofthetimeapartspendsontheshopfloorisidletime/theother5%isdividedbetweensetupandteardownofthemachinetool/Thefuturebreakdownofthe5%o
5、fon-machinetimewasdevelopedbyDunlap/Basedonthisestimate/only24%ofthe5%istimewhichactuallyinvolvescutting；i/e//partsarebeingmachinedduringonly1/2%ofthetotaltimespentinmanufacturing/Grouptechnologymakespossibletheapplicationofseveralmethodsofanalysiswhichassistinmakingbatchproductionmoreefficientbyred
6、ucingpartvarietyviapartfamiliesandimprovingthroughoutandwork-in-processinventory/Itisforthisreasonthatgrouptechnologyisbecomingakeyconceptinmanufacturing/2DefinitionManufacturingphilosophytosome/fundamentalbuildingblockformoreefficientproductiontomost/grouptechnologyisasimpleconceptwhichutilizes/exp
7、loitssimilaritiesformoreefficientproductioninbathmanufacturing/Grouptechnologyusuallyclassifiespartsintheformofacodewhichisassignedtoeachpartbasedonitsshapeorproductionprocessingcharacteristics/Inuse/codingpartsassistsinthecontrolofplanningandprocessing/Thisaddedcontrol/whichexploitssimilarities/lea
8、dstoeconomiesintheoverallmanufacturingprocess/Theactualoperatorontheshopfloormayneverknowthiscode/butdesigners/engineers/andplannersfinditaninvaluabletool/allowingthemtodomoreproductiveandusefulanalysis/3GeneralBenefitsInpractice/grouptechnologyisreallynothingmorethananinformation/indexingsystem/How
9、ever/becauseofitsfocusonpartdesignandprocessingsimilarities/analysisispossiblewhichcreatesmanufacturingeconomiesofscale/encouragesstandardization/andeliminatesduplicationindesignandprocessplanning/Massproductionenjoysthebenefitsofwhatarecalledeconomiesofscale/Economiesofscaleachievedbyprocessingalar
10、genumberofpartsoverthesameworkstationsorequipment/Thisresultinlesslaborperpart/moreefficientmachineutilization/andafasterturnoverofinventory/Batchproductioninthepasthasnotenjoyedeconomiesofscalebecauseoftheneedtoremainflexibleforchangingparttypesandproducts/However/bygroupingpartsintofamiliesbasedon
11、theirsimilarities/muchofthemanufacturingprocessingofthesepartscanbedoneonentirefamilies/Thisincreasesthenumberofpartsprocessedwiththesameequipmentconditions/therebypermittingsomeoftheeconomiesofscaleofmassproduction/Standardizationisachievedinbothdesignandpartprocessplanning/Essentially/grouptechnol
12、ogycreatesanefficientdesignretrievalsystemsincepartshavebeencodebasedonshape/Similardesignarelocatedquicklyandaspectssuchasparttolerancesandproducibilitycanbebetterunderstood/moreeasilyapplied/andkeptmoreconsistentfromdesigntodesign/Whenstandardizedprocessplanesaredevelopedandincludeinthegrouptechno
13、logycode/newpartsandrepeatorderscanfollowsimilarprocessingroutesthroughtheshopfloor/simplifyingschedulingandflowthroughtheshop/Grouptechnologyeliminatesduplication/Inbothdesignandprocessplanning/thereismuchles“reinventingofthewheel”sincethereissufficientretrievalofstandarddesignsandprocessplans/4App
14、licationofGTinProcessPlanningAlthoughmanyareasofbusinessoperationcanbenefitfromGT/manufacturing/theoriginalapplicationarea/continuestobetheplacewhereGTismostwidelypracticed/Twoimportanttasksinmanufacturingplanningandmanufacturingengineeringareschedulingandprocessplanning/Jobschedulingsetstheorderinw
15、hichpartsshouldbeprocessedandcandetermineexpectedcompletiontimesforoperationandorders/Processplanning/ontheotherhand/decidesthesequenceofmachinestowhichapartshouldberoutedwhenitismanufacturedandtheoperationsthatshouldbeperformedateachmachine/Processplanningalsoencompassestool/jig/andfixtureselection
16、aswellasdocumentationofthetimestandards(runandsetuptime)associatedwitheachoperation/Processplanningcandirectlyaffectschedulingefficiencyand/thus/manyoftheperformancemeasuresnormallyassociatedwithmanufacturingplanningandcontrol/Someofthelargestproductivitygainshavebeenreportedinthecreationofprocesspl
17、ansthatdeterminehowapartshouldbeproduced/Withcomputer-aidedprocessplanning(CAPP)andGTitispossibletostandardizesuchplans/reducethenumberofnewones/andstore/retrieve/edit/andprintthemoutveryefficiently/Processplanningnormallyisnotaformalprocedure/Eachtimeanewpartisdesigned/aprocessplannerwilllookatthed
18、rawinganddecidewhichmachinetoolsshouldprocesstheparts/whichoperationsshouldbeperformed/andinwhatsequenceTherearetworeasonswhycompaniesoftengenerateexcessprocessplans/First/mostcompanieshaveseveralplanners/andeachmaycomeupwithadifferentprocessplanfortheverysamepart/Second/process；planningisdevelopedw
19、iththeexistingconfigurationofmachinetoolsinmind/Overtime/theadditionofnewequipmentwillchangethesuitabilityofexistingplans/Rarelyarealterationstooldprocessplansmade/Onecompanyreportedlyhad477processplansdevelopedfor523differentgears/Acloselookrevealedthatmorethan400oftheplanscouldbeeliminated/Process
20、planningusingCAPPcanavoidtheseproblems/ProcessplanningwithCAPPtakestwodifferentforms；Withvariant-basedplanning/onestandardizedplan(andpossiblyoneormorealternateplans)iscreatedandstoredforeachpartfamily/WhentheplannerenterstheGTcodeforapart/thecomputerwillretrievethebestprocessplan/Ifnoneexists/theco
21、mputerwillsearchforroutingsandoperationsforsimilarparts/TheplannercanedittheschemeontheCRTscreenbeforeprintout/Withgenerativeplanning/whichcanbutdoesnotnecessarilyrelyoncodedandclassifiedparts/thecomputerformstheprocessplanthroughaseriesofquestionsthecomputerposesonthescreen/Theendproductisalsoastan
22、dardizedprocessplan/whichisthebestplanforaparticularpart/Thevariant-basedapproachreliedonestablishedplansenteredintothecomputermemory/whilethegenerativetechniquecreatestheprocessplansinteractively/relyingonthesamelogicandknowledgethataplannerhas/Generativeprocessplanningismuchmorecomplexthanvariant-
23、basedplanning；infact/itapproachestheartofartificialintelligence/Itisalsomuchmoreflexible；bysimplychangingtheplanninglogic/forinstance/engineerscanconsidertheacquisitionofanewmachinetool/Withthevariant-basedmethod/theengineersmustlookoverandpossiblycorrectallplansthatthenewtoolmightaffect/CAPPpermits
24、creationanddocumentationofprocessplansinafractionofthetimeitwouldtakeaplannertodotheworkmanuallyandvastlyreducesthenumberoferrorsandthenumberofnewplansthatmustbestored/Whenyouconsiderthatplansnormallyarehandwrittenandthatprocessplannersspendasmuchas30%oftheirtimepreparingthem/CAPPScontributionofstan
25、dardizedformatsforplansandmorereadabledocumentsisimportant/CAPP/ineffect/functionsasadvancedtexteditor/Furthermore/itcanbelinkedwithanautomatedstandarddatasystemthatwillcalculateandrecordtheruntimesandthesetuptimesforeachoperation/CAPPcanleadtolowerunitcoststhroughproductionofpartsinanoptimalway/Tha
26、tis/costsavingscomenotonlyviamoreefficientprocessplanningbutalsothroughreducedlabor/material/tooling/andinventorycosts/GTcanhelpinthecreationofprogramsthatoperatenumerically(NC)machinery/narearelatedtoprocessplanning/Forexample/aftertheengineersatOtisEngineeringhadformedpartfamiliesandcells/thetimet
27、oproduceanewNCtapedroppedfrombetween4and8hoursto30minutes/ThecompanytherebyimprovedthepotentialforuseofNCequipmentonbatcheswithsmallmanufacturingquantities/编者：吴非晓等机械英语2外语教学与研究出版社2002/7成组技术在当今的制造环境下，尤其是对批量生产来说，成组技术（GT）是一个很重要的生产方式而且它正变得越来越重要。其原因在于，当成组技术发挥最大作用的时候，能够影响大多数的制造领域，其中包括设计、工艺规划、调度、路线、工厂布局、采购、
28、质量保证、车***应用、***设计、生产能力设计及组装。1简介成组技术是一个以各种形式广泛应用的简单概念。基于各种原因，我们有理由根据事物的共同特征把它们收集并联系在一起。对于植物、动物和化合物来说，每个人都很熟悉这种方法。在制造业内，这种***结构也被用于硬件和其它明显相似的产品中。成组技术对于生产团体来说，代表着具有具体价值的***分类。它早就被广泛应用，大约有50%的生产企业在使用某种形式的成组技术。由于零件多种多样以及生产车间使用的车***的通用特性（灵活性要求），造成了批量和规模生产效率差的情况很多。一份辛辛那提麦尔克伦的研究表明，实际上一个零件花费在生产车间的时间有95%是闲置的，另外5%的时间
29、在车***的装配和拆卸之间进行分配。Dunlap对这5%的机上时间进一步的分解进行了研究。据此估计，5%的机上时间中只有24%的时间用于切割。也就是说，只有1/2%的总时间用于零部件的加工。成组技术能够利用几中不同分析的方法，通过零件族来减少零件的种类，从而使批量生产更具有效率，提高生产能力并缓解加工过程的库存问题。正是由于这个原因，成组技术才在生产中成为一个至关重要的概念。2定义成组技术在某种程度上是一种生产观念，而在很大程度上是高效率生产的基本构件，它是一个简单的概念，它在批量生产过程中利用或使用相似性提高制造效率。成组技术通常利用代码将零件分类。代码是根据零件的形状或生产过程的特征分配给每个零件的。使用中，代码零件有助于对规划和加工的控制。这种利用相似性的附加控制能给整个生产过程带来许多经济效益。车间里的实际操作者可能永远也不知道这个代码，但是设计者、工程师和规划人员把它当成一种最宝贵的工具，能够使他们进行更加有用和富有成效的分析。3益处实际上，成组技术其实就是一个信息或索引系统。然而，由于它着眼于零件设计和加工的相似性就有可能进行分析，规模生产的经济效益，促进标准化并避免重复设计和工艺规划。批量生产有利于规模经济。规模经济效益通过用同一车间或设备加工大量零
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