一、Diehistoryanddietrend1、DiepositioninindustrialproductionWithmoldcomponents,withhighefficiency,goodquality,lowcost,savingenergyandrawmaterialsandaseriesofadvantages,withthemoldworkpiecespossesshighaccuracy,highcomplexity,highconsistency,highproductivityandlowconsumption,othermanufacturingmethodscannotmatch.Havealreadybecomeanimportantmeansofindustrialproductionandtechnologicaldevelopment.Thebasisofthemodernindustrialeconomy.Moldisahigh-volumeproductswiththeshapetool,isthemainprocessofindustrialproductionequipment.Thedevelopmentofmodernindustrialandtechnologicalleveldependslargelyonthelevelofindustrialdevelopmentdie,sodieindustrytonationaleconomicandsocialdevelopmentwillplayanincreasingrole.March1989theStateCouncilpromulgated"onthecurrentindustrialpolicydecisionpoints"inthemoldasthemachineryindustrytransformationsequenceofthefirst,productionandcapitalconstructionofthesecondsequence(afterthelarge-scalepowergenerationequipmentandthecorrespondingpowertransmissionequipment),establishtoolingindustryinanimportantpositioninthenationaleconomy.Since1997,theyhavetomoldanditsprocessingtechnologyandequipmentincludedinthe"currentnationalfocusonencouragingthedevelopmentofindustries,productsandtechnologiescatalog"and"toencourageforeigninvestmentindustrydirectory."ApprovedbytheStateCouncil,from1997to2000,morethan80professionalmoldfactoryowned70%VATrefundofpreferentialpoliciestosupportmoldindustry.AllthesehavefullydemonstratedthedevelopmentoftheStateCouncilandstatedepartmentstoolingindustryattentionandsupport.Moldaroundtheworldaboutthecurrentannualoutputof60billionU.S.dollars,Japan,theUnitedStatesandotherindustrializedcountriesdieofindustrialoutputvalueofmorethanmachinetoolindustry,beginningin1997,China'sindustrialoutputvaluehasexceededthemoldmachinetoolindustryoutput.Accordingtostatistics,homeappliances,toysandotherlightindustries,nearly90%ofthepartsareintegratedwithproductionofchopsticks;inaircraft,automobiles,agriculturalmachineryandradioindustries,theproportionexceeded60%.Suchasaircraftmanufacturing,theuseofacertaintypeoffighterdiesmorethan30,000units,ofwhichthehost8000sets,2000setsofengines,auxiliary20000sets.Fromtheoutputofview,sincethe80's,theUnitedStates,Japanandotherindustrializedcountriesdieindustryoutputvaluehasexceededthemachinetoolindustry,andtherearestillrising.Productiontechnology,accordingtotheInternationalAssociationpredictsthatin2000,theproductbestpiecesofrough75%,50%willbefinishedmoldcompleted;metals,plastics,ceramics,rubber,buildingmaterialsandotherindustrialproducts,mostofthemoldwillbecompletedinmorethan50%metalplates,morethan80%ofallplasticproducts,especiallythroughthemoldinto.2、ThehistoricaldevelopmentofmoldTheemergenceofmoldcanbetracedbackthousandsofyearsago,potteryandbronzefoundry,butthelarge-scaleuseiswiththeriseofmodernindustryanddeveloped.The19thcentury,withthearmsindustry(gun'sshell),watchindustry,radioindustry,diesarewidelyused.AfterWorldWarII,withtherapiddevelopmentofworldeconomy,itbecameamassproductionofhouseholdappliances,automobiles,electronicequipment,cameras,watchesandotherpartsthebestway.Fromaglobalperspective,whentheUnitedStatesintheforefrontofstampingtechnology-manydieofadvancedtechnologies,suchassimplemold,highefficiency,mold,dieandstampingthehighlifeautomation,mostlyoriginatedintheUnitedStates;andSwitzerland,fineblanking,coldinGermanyextrusiontechnology,plasticprocessingoftheSovietUnionareattheworldadvanced.50's,moldindustryfocusisbasedonsubscriberdemand,productioncanmeettheproductrequirementsofthemold.Multi-diedesignruleofthumb,referencehasbeendrawingandperceptualknowledge,onthedesignofmoldpartsofalackofrealunderstandingoffunction.From1955to1965,isthepressureprocessingofexplorationanddevelopmentofthetimes-themaincomponentsofthemoldandthestressstateofthefunctionofamathematicalsub-bridge,andtocontinuetoapplytoon-sitepracticalknowledgetomakestampingtechnologyinallaspectsofaleapindevelopment.Theresultissummarizedmolddesignprinciples,andmakesthepressuremachine,stampingmaterials,processingmethods,plumwithastructure,moldmaterials,moldmanufacturingmethod,thefieldofautomationdevices,anewlooktothepracticaldirectionofadvance,sothatpressingprocessingapparatuscapableofproducingqualityproductsfromthefirststage.Intothe70'stohighspeed,launchtechnology,precision,security,developmentofthesecondstage.Continuetoemergeinthisprocessavarietyofhighefficiency,businesslife,high-precisionmulti-functionalautomaticschooltohelpwith.Representedbythenumberofworkingplacesasmuchasotherprogressivedieanddozensofmulti-stationtransferstationmodule.Onthisbasis,hasdevelopedbothacontinuouspressingstationtherearemoreslideformingstationofthepress-bendingmachine.Inthemeantime,theJapanesestandtotheworld'slargest-themoldintothemicron-levelprecision,dielife,alloytoolsteelmoldhasreachedtensofmillionsoftimes,carbidesteelmoldtoeachofhundredsofmillionsoftimespminutesforstampingthenumberofsmallpressesusually200to300,upto1200timesto1500times.Inthemeantime,inordertomeetproductupdatesquickly,withtheshortduration(suchascarsmodified,refurbishedtoys,etc.)needavarietyofeconomic-typemold,suchaszincalloydiedown,polyurethanerubbermold,diesteelskin,alsohasbeenverygreatdevelopment.Fromthemid-70ssofarcanbesaidthatcomputer-aideddesign,supportingthecontinuousdevelopmentofmanufacturingtechnologyofthetimes.Withtheprecisionandcomplexityofmoldrising,acceleratingtheproductioncycle,themoldindustry,thequalityofequipmentandpersonnelarerequiredtoimprove.Relyoncommonprocessingequipment,theirexperienceandskillscannotmeettheneedsofmold.Sincethe90's,mechanicalandelectronictechnologiesincloseconnectionwiththedevelopmentofNCmachinetools,suchasCNCwirecuttingmachine,CNCEDM,CNCmilling,CNCcoordinategrindingmachineandsoon.Theuseofcomputerautomaticprogramming,controlCNCmachinetoolstoimprovetheefficiencyintheuseandscope.Inrecentyears,hasdevelopedacomputertotime-sharingbythewayagroupofdirectmanagementandcontrolofCNCmachinetoolsNNCsystem.Withthedevelopmentofcomputertechnology,computershavegraduallyintothemoldinallareas,includingdesign,manufacturingandmanagement.InternationalAssociationfortheStudyofproductionforecaststo2000,asameansoflinksbetweendesignandmanufacturingdrawingswillloseitsprimaryrole.AutomaticDesignofdiemostfundamentalpointistoestablishthemoldstandardanddesignstandards.Togetridofthepeopleofthepast,andpracticalexperiencetojudgethecompositionofthedesigncenter,wemusttakepastexperiencesandwaysofthinking,forseries,numericalvalue,thenumberoftype-based,asthedesigncriteriatothecomputerstore.Componentsaredrybecauseofmoldconstitutesamillionotherdifferences,tocomeupwithacanadapttovariouspartsofthedesignsoftwarealmostimpossible.Butsomeproductsdonotchangetheshapeofparts,moldstructurehascertainrules,canbesummedupfortheautomaticdesignofsoftware.IfaJapanesecompany'sCDMsystemforprogressivediedesignandmanufacturing,includingtheimportationofpartsofthefigure,roughstart,striplayout,determinethesizeandstandardtemplates,assemblydrawingandparts,theoutputNCprogram(forCNCmachiningCenterandlinecuttingprogram),etc.,usedin20%ofthetimebyhand,reducetheirworkinghoursto35hours;fromJapanintheearly80swillbethree-dimensionalcad/camsystemforautomotivepaneldie.Currently,thephysicalpartsscanninginput,maplinesanddatainput,geometricform,display,graphics,annotationsandthedataisautomaticallyprogrammed,resultingineffectivecontrolmachinetoolcontrolsystemofpost-processingdocumentshavereachedahighlevel;computerSimulation(CAE)technologyhasmadesomeachievements.Athighlevels,CAD/CAM/CAEintegration,thatdataisintegrated,cantransmitinformationdirectlywitheachother.Achievenetwork.Present.Onlyafewforeignmanufacturerscandoit.3、Thetrendofthedie(1)moldsoftwarefeaturesintegratedDiesoftwarefeaturesofintegratedsoftwaremodulesrequiredrelativelycomplete,whilethefunctionmoduleusingthesamedatamodel,inordertoachieveSyndicatednewsmanagementandsharingofinformationtosupportthemolddesign,manufacture,assembly,inspection,testingandproductionmanagementoftheentireprocesstoachieveoptimalbenefits.SeriessuchastheUKDelcam'ssoftwarewillincludeasurface/solidgeometricmodeling,engineeringdrawingcomplexgeometry,advancedrenderingindustrialdesign,plasticmolddesignexpertsystem,complexphysicalCAM,artisticdesignandsculptureautomaticprogrammingsystem,reverseengineeringandcomplexsystemsphysicallinemeasurementsystems.Ahigherdegreeofintegrationofthesoftwareincludes:Pro/ENGINEER,UGandCATIA,etc..ShanghaiJiaotongUniversity,ChinawithfiniteelementanalysisofmetalplasticformingsystemsandDieCAD/CAMsystems;BeijingBeihangHaierSoftwareLtd.CAXASeriessoftware;JilinGoldGridEngineeringResearchCenterofthestampingdiemoldCAD/CAE/CAMsystems.(2)molddesign,analysisandmanufactureofthree-dimensionalTwo-dimensionalmoldoftraditionalstructuraldesigncannolongermeetmoderntechnicalrequirementsofproductionandintegration.Molddesign,analysis,manufacturingthree-dimensionaltechnology,paperlesssoftwarerequiredtomoldanewgenerationofthree-dimensional,intuitivesensetodesignthemold,usingthree-dimensionaldigitalmodelcanbeeasilyusedintheproductstructureofCAEanalysis,toolingmanufacturabilityevaluationandCNCmachining,formingprocesssimulationandinformationmanagementandsharing.SuchasPro/ENGINEER,UGandCATIAsoftwaresuchaswithparametric,feature-based,allrelevantcharacteristics,sothatmoldconcurrentengineeringpossible.Inaddition,CimatrancompanyMoldexpert,Delcam'sPs-moldandHitachiShipbuildingofSpace-E/moldareprofessionalinjectionmold3Ddesignsoftware,interactive3Dcavity,coredesign,moldbasedesignconfigurationandtypicalstructure.AustraliancompanyMoldflowrealisticthree-dimensionalflowsimulationsoftwareMoldflowAdvisersbeenwidelypraisedbyusersandapplications.ChinaHuazhongUniversityofSciencehavedevelopedsimilarsoftwareHSC3D4.5FandZhengzhouUniversity,Z-moldsoftware.Formanufacturing,knowledge-basedintelligentsoftwarefunctionisameasureofdieimportantsignofadvancedandpracticalone.(3)moldsoftwareapplications,networkingtrendWiththemoldintheenterprisecompetition,cooperation,productionandmanagement,globalization,internationalization,andtherapiddevelopmentofcomputerhardwareandsoftwaretechnology,theInternethasmadeinthemoldindustry,virtualdesign,agilemanufacturingtechnologybothnecessaryandpossible.TheUnitedStatesinits"21stCenturyManufacturingEnterpriseStrategy"thattheautoindustryby2006toachieveagilemanufacturing/virtualengineeringsolutionstoautomotivedevelopmentcycleshortenedfrom40monthsto4months.二、TheinjectionandCompressionMoldingInjectionmoldingsiprincipallyusedfortheproductionofthethermoplasticparts,althoughsomeprogresshasbeenmadeindevelopingamethodforinjectionmoldingsomethermosettingmaterials.Theproblemofinjectingameltedplasticintoamoldcavityformareservoirofmeltedmaterialhasbeenextremelydifficulttosolveforthermosettingplasticswhichcureandhardenundersuchconditionswithinafewminutes.Theprincipleofinjectionmoldingisquitesimilartothatofdie-casting.Theprocessconsistsoffeedingaplasticcompoundinpowderedorgranularformfromahopperthroughmeteringandmeltingstagesandtheninjectingitintoamold.Afterabriefcoollingperiod,themoldisopenedandthesolidifiedpartejected.Injection-moldingmachinescanbearrangedformanualoperation,automaticsingle-cucleoperation,andfullautomaticoperation.Theadvantageofinjectionmoldingare:ahighmoldingspeedadaptedformassproductionispossible;thereisawidechoiceofthermoplasticmaterialsprovidingavarietyofusefullproperties;itispossibletomoldthreads,undercuts,sideholes,andlargethinsections.Severalmethodsareusedtoforceorinjectthemeltedplasticintothemold.Themostcommonlyusedsysteminthelargermachinesisthein-linereciprocatingscrew.Thescrewactsasacombinationandplasticizingunit.Astheplasticisfedtotherotatingscrew,itpassesthroughthreezonesasshown:feed,compression,andmetering.Afterthefeedzone,thescrew-flightdepthisgraduallyreduced,forcingtheplastictocompress.Theworkisconvertedtoheatbyshearingtheplastic,makingitasemifluidmass.Inthemeteringzone,additionalheatisappliedbyconductionfromthebarrelsurface.Asthechamberinfrontofthescrewbecomesfilled,itforcesthescrewback,trippingalimitswitchthatactivatesahydrauliccylinderthatforcesthescrewforwardandinjectsthefluidplasticintotheclosedmold.Anantiflowbackvalvepreventsplasticunderpressurefromescapingbackintothescrewflights.Theclampingforcethatamachineiscapableofexertingispartofthesizedesignationandismeasuredintons.Arule-of-thumbcanbeusedtodeterminethetonnagerequiredforaparticularjob.Itisbasedontwotonsofclampforcepersquareinchofprojectedarea.Iftheflowpatternisdifficultandthepartsarethin,thismayhavetogotothreeorfourtons.Manyreciprocating-screwmachinesarecapableofhandingthermosettingplasticmaterials.Previouslythesematerialswerehandledbycompressionortransfermolding.Thermosettingmaterialscureorpolymerizeinthemoldandareejectedhotintherangeof375℃～410TheimportanceofInjectingthemoldare:⑴、Plasticshavethedensitysmall,thequalitylight,thespecifictenacitybig,theinsulatingpropertygood,thedielectriclosslow,thechemicalstabilitystrong,theformationproductivityhighandthepriceinexpensiveandsoonthemerits,obtaineddaybydaythewidespreadapplicationinthenationaleconomyandpeople'sdailylifeeachdomain,asearlyasinthebeginningof1990s,theplasticannualoutputalreadysurpassedthesteelandironandthenon-ferrousmetalannualoutputsumtotalaccordingtothevolumecomputation.Inmechanicalandelectrical(forexampleso-calledblackelectricalappliances),domainsandsoonmeasuringappliance,chemical,theautomobileandastronauticsaviation,theplastichasbecomethemetalthegoodsubstitutionmaterial,hadthemetalmaterialplastictendency.⑵、Taketheautomobileindustryastheexample,asaresultoftheautomobilelightweight,thelowenergyconsumptiondevelopmentrequest,theautomobilesparepartmaterialconstitutionoccurredobviouslyhasmodelledthebandsteelthechange,atpresentourcountryautomobileplasticaccountsfor5%whichtheautomobilewasself-possessedto6%,butoverseashasreached13%,forecastaccordingtotheexpert,theautomobileplasticbicycleamountusedwillalsobeablefurthertoincrease.Onmodernvehicles,regardlessofisoutsideinstallstheassorteditems,theinternalinstallationassorteditems,thefunctionandthestructuralelement,allmayusetheplasticmaterial,outsideinstallstheassorteditemstohavethebumper,thefender,thewheelhubcap,theairdeflectorandsoon;Aftertheinternalinstallationassorteditemshaveinthedisplayboard,thevehicledoortheboard,thevice-displayboard,thesundrygoodsboxlid,thechair,theguardshieldandsoon;Thefunctionandthestructuralelementhavethefueltank,theradiatorheader,thespatialfilterhood,thefanbladeandsoon.Statisticshaveindicated,ourcountryin2000automobileoutputmorethan200tenthousand,thevehicleamountedto1,380,000tonswiththeplastic.Lookedfromthedomesticandforeignautomobileplasticapplicationsituationthat,theautomobileplasticamountusedalreadybecameoneofweightautomobileproductiontechnicallevelsymbols.⑶、Injectionofamoldingformationasplasticworkpiecemosteffectiveformationmethodsbecausemaybyonetimetakeshapeeachkindofstructurecomplex,thesizepreciseandhasthemetaltoinlayaproduct,andtheformationcycleisshort,maybymoldmulti-cavities,theproductivitybehigh,whenmassproductionsthecostisveryinexpensive,easytorealizetheautomatedproduction,thereforeholdstheextremelyimportantstatusintheplasticprocessingprofession.Statisticshaveindicated,plasticmoldcompositionallmolds(includingmetalpattern)38.2%,theplasticproductgrossweightabout32%isusesininjectingtheformation,80%aboveengineeringplasticsproductallmustusetheinjectionformationwayproduction.4.countsaccordingtothecustoms,ourcountryin2000altogetherimportedmold977,000,000USdollars,inwhichplasticmoldingformsaltogether550,000,000USdollars,occupiedfor56.3%,2001yearsaltogethertoimportmold1,112,000,000USdollars,inwhichplasticmoldingformsaltogether616,000,000USdollars,accountedfor55.4%.Fromthevariety,theimportvolumebiggestistheplasticmoldingforms.⑷、Countsaccordingtothecustoms,ourcountryin2000altogetherimportedmold977,000,000USdollars,inwhichplasticmoldingformsaltogether550,000,000USdollars,occupiedfor56.3%,2001yearsaltogethertoimportmold1,112,000,000USdollars,inwhichplasticmoldingformsaltogether616,000,000USdollars,accountedfor55.4%.Fromthevariety,theimportvolumebiggestistheplasticmoldingforms.Incompressionmoldingthepalsticmaterialaspowderorpreformsisplacedintoaheatedsteelmoldcavity,Sincethepartingsurfaceisinahorizontalplane,theupperhalfofthemolddescendsvertically.Itclosesthemoldcavityandpressuresforapredeterminedperiod.Apressureoffrom2to3tonssquareinchandatemperaureatapproximately350Fconvertstheplastictoasemiliquidwhichflowstoallpartsofthemoldcavity.Usuallyfrom1to15minutesisrequiredforcuring,altougharecentlydevelopedalkydplasticwillcureinlessthan25secends.Themoldisthenopendedandthemoldedpartremoved.Ifmetalinsersaredesiredintheparts,theyshouldbeplacedinthemoldcavityonpinsorintheholesbeforetheplasticisloaded.Also,thepreformsshouldbepreheatedbeforeloadingintothemoldcavitytoeliminategases,inproveflow,anddecreasecuringtime.Dieletricheatingisaconvenientmethodofheatingthepreforms.Sincetheplasticmaterialisplaceddirectlyintothemoldcavity,themolditselfcanbesimplerthanthoseusedforothermoldingprecesses.Gatesandspruesareunnecessary.Thisalsoresultsinasavinginmaterial,becausetrimmed-offgatesandsprueswouldbeacompletelossofthethermosettingplastic.Thepressrequirethefullattentionofoneoperator.However,severalsmallerpressescanbeoperatedbyoneoperator.Thepressesareconvenientlylocatedsotheoperatorcaneasilymovefromonetothenext.Bythetimehegetsaroundtoaparticularpressagain,thatmoldwillbereadytoopen.thethermosettingplasticswhichhardenunderheatandpressurearesuitableforcompressionmoldingandtransfermolding.Itisnotpracticaltomoidshermoplasticmaterialsbythesemethods,sincethemoldswouldhavetobealternatelyheatedandcooled.Inordertohardenandejectthermoplasticpartsformthemold,coolingwouldbenecessary.Typesofmoldsforcompressionmolding.Themoldsusedforcompressionmoldingareclassifiedintofourbasictypes,namely,positivemolds,landedpositivemold,flash-typemolds,andsemipositivemolds.Inapositivemoldtheplungerontheuppermoldentersthelowermoldcavity.sincetherearenolandsorstopsonthelowerdie,theplungercompletelytraptheplasticmaterialanddescendswithfullpressureonthecharge.Adensepartwithgoodelectricalandphysicalpropertiesisproduced.Theamountofplasticplacedinthediecavitymustbeaccuratelymeasured,sinceitdeterminesthethicknessofthepart.Alandedpositivemoldissimilartoapositivemoldexceptthatlandsareaddedtostopthetraveloftheplungeratpredeterminedpoint.Inthiscase,thelandsabsorbsomeofthepressurethatshouldbeexertedontheparts.Thethicknessofthepartswillbeaccuratelycontrolled,butthedensitymayvarycansideraby.Inaflash-typemold,flashredgesareaddedtithetopandbottommolds.Astheuppermoldexertspressureontheplastic,excessmaterialisforcedoutbetweentheflashridgeswhereitformsflash.Thisflashisfurthercompressed.becomeshardened,andfinallystopsthedownardthaveloftheuppermold.Aslightexcessoftheplasticmaterialisalwayscharedtoensuresufficientpressurstoproduceadensemoldedpart.Thistypeofmoldiswidelyusedbecauseitiscomparativelyeasytoconstructanditcontrolsthicknessanddensitywithincolselimits.Thesemipositivemoldisacombinationodtheflashtypeandlandedposivemolds.Inadditiontotheflashridges,alandisemployedtorestrictthetraveloftheuppermold.三、ThelatheThelatheisoneofthemostusefulandversatilemachinesintheworkshop,andcapableofcarryingoutawidevarietyofmachiningoperations.Themaincomponentsofthelathearetheheadstockandtailstockatoppositeendsofabed,andatool-postbetweenthemwhichholdsthecuttingtool.Thetool-poststandsonacross-slidewhichenablesittomovesidewardsacrossthesaddleorcarriageaswellasalongit,dependingonthekindofjobitisdoing.Theordinarycentrelathecanaccommendateonlyonetoolatatimeonthetool-post,butaburretlatheiscapableofholdingfiveormoretoolsontherevolvingturret.Thelathebedmustbeverysolidtopreventthemachinefrombendingortwistingunderstress.Theheadstockincorporatesthedrivingandgearmechanism,andaspindlewhichholdstheworkpieceandcausesittorotateataspeedwhichdependslargelyonthediameteroftheworkpiece.Abaroflargediametershouldnaturallyrotatemoreslowlythanaverythinbar,thecuttingfeed-shaftfromtheheadstockdrivesthetool-postalongthesaddle,eitherforwardsorbackwards,atafixedanduniformspeed.Thisenablesrotationoftheshaft,andthereforetheforwardorbackwardmovementofthetool-post.Thegearwhichtheoperatorwillselectdependsonthetypeofmetalwhichheiscuttingandtheamountofmetalhehastocutoff.Foradeeporroughingcuttheforwardmovementofthetoolshouldbelessthanforafinishingcut.Centresarenotsuitableforeveryjobonthelathe.Theoperatorcanreplacethembyvarioustypesofchucks,whichholdtheworkbetweenjaws,orbyafront-plate,dependingontheshapeofworkandtheparticularcuttingoperation.Hewilluseachuck,forexample,toholdashortpieceofwork,orworkfordrilling,boringorscrew-cutting.Atransversemovementofthetool-postacrossthesaddleenablesthetooltocutacrossthefaceoftheworkpieceandgiveitaflatsurface.Forscrew-cutting,theoperatorengagestheleadscrew,alongscrewedshaftwhichrunsalonginfrontofthebedandwhichrotateswiththespindle.Thelead-screwdrivesthetool-postforwardalongthecarriageatthecorrectspeed,andthisensuresthatthethreadsonthescrewareofexactlytherightpitch.Theoperatorcanselectdifferentgearspeeds,andthiswillaltertheratioofspindleandlaedscrewspeedsandthereforealterthepitchofthethreads.Areversingleverontheheadstockenableshimtoreversethemovementofthecarriageandsobringthetoolbacktoitsoriginalposition.Thepurposeofanymachinetoolistoremovemetal.Eachmachinetoolremovesmetalinadifferentway.Forexample,inonetype(thelathe)metalisremovedbyasinglepointtoolastheworkisrotated,whereasinanothertype(themillingmachine)acutterisrotatedandmetalisremovedastheworkisprogressedbeneathit.Whichmachinetoolistobeusedforaparticularjobdependstoalargeextentuponthetypeofmachiningrequired.Thereis,however,acertainamountofoverlappingandsomemachinetoolscanbeutilizedforseveraldifferentoperationsbutitmustnotbeassumedthattheparticularmachinetoolisrestrictedtotheoperationshown.Themachinetoolswhichwillbefoundinthemoderntoolroomareasfollow：Lathesforturning,boringandscrewcutting,ect.Theprimarypurposeofthelatheistomachinecylindricalforms.Thecontourisgeneratedbyrotatingtheworkwithrespecttoasingle-pointcuttingtool.Cylindricalgrindingmachinesfortheproductionofprecisioncylindricalsurfaces.Thecylindricalgrindingmachineisusedforprecisiongrindingcylindricalmouldparts.Metalisremovedbytheactionofabrasivegrindingwheelwhichisbroughtintocontactwithacontra-rotatingworkpiece.Shapingandplanningmachinesforthereductionofsteelblocksandplatestotherequiredthicknessandfor‘squaringup’theseplates.Astheprimarypurposeofashapingmachineistoproduceflatblocks.Theworkpieceismountedonatableandareciprocatingsingle-pointtoolremovesmetalinaseriesofstraightcuts.Surfacegrindingmachinesfortheproductionofprecisionflatsurfaces.Anexcellentsurfacefinishcombinedwithaccuracycanbeachievedonhardorsoftsteelwiththesurfacegrindingmachine.Theworkpieceismountedonatablewhichisreciprocatedbeneatharotatingabrasivegrindingwheelandmetalisremovedinaseriesofstraightcuts.Millingmachinesfortherapidremovalofmetal,formachiningslots,recesses,boringholes,