仓库作业与仓储规划.ppt

WarehouseScience,颜涛,浙江财经学院工商管理学院物流教研室E-mail:yytt195113656633908,第一章Warehouserationale,仓库是什么？Warehousesarethepointsinthesupplychainwhereproductpauses,howeverbriefly,andistouched.为什么需要仓库？Tobettermatchsupplywithcustomerdemand:demandcanchangequickly,butsupplytakeslongertochange.Warehousescanalsobufferagainstsuddenchangesinsupply.ToconsolidateproductToprovidevalue-addedprocessing,仓库分类Whiletherearemanytypesofwarehousesinthesupplychain,thereisasystematicwaytothinkaboutawarehousesystemregardlessoftheindustryinwhichitoperates.,第一章Warehouserationale,第二章Materialflow,什么是供应链？The“supplychain”isthesequenceofprocessesthroughwhichproductmovesfromitsorigintowardthecustomer.Pipeline与incompressiblefluidmodel流体模型,流体模型对我们的启发:Keeptheproductmoving;avoidstartsandstops,whichmeanextrahandlingandadditionalspacerequirements.Avoidlayoutsthatimpedesmoothflow.Identifyandresolvebottleneckstoflow.流体模型与JIT的关系该模型是对现实的一种近似,第二章Materialflow,库位固定库位：Thesimplestisdedicatedstorage,inwhicheachlocationisreservedforanassignedproductandonlythatproductmaybestoredthere.固定库位的好处（Pros）Becausethelocationsofproductsdonotchange,morepopularitemscanbestoredinmoreconvenientlocationsandworkerscanlearnthelayout,allofwhichmakesorder-pickingmoreefficient.,第二章Materialflow库位：固定库位与共享库位Storage:“Dedicated”versus“Shared”,固定库位的缺点（Cons)：Theproblemwithdedicatedstorageisthatitdoesnotusespaceefficiently.共享库位,第二章Materialflow库位：固定库位与共享库位Storage:“Dedicated”versus“Shared”,共享库位的缺点：需要仓库管理信息系统的支持工人操作时间成本及复杂性增加怎么办？,第二章Materialflow库位：固定库位与共享库位Storage:“Dedicated”versus“Shared”,共享库位对提高仓库存储空间利用率的测算Howmuchimprovementinspaceutilizationispossiblewithsharedstorage?考虑一种产品，两周的需求量，存储在两个相等大小的库位上且需求速率恒定的情形空间利用率=平均库存/平均所需存储空间,第二章Materialflow库位：固定库位与共享库位Storage:“Dedicated”versus“Shared”,第三章：仓库作业Warehouseoperations,仓库作业的总体特点：Awarehousereorganizesandrepackagesproduct.Producttypicallyarrivespackagedonalargerscaleandleavespackagedonasmallerscale.Inotherwords,animportantfunctionofthiswarehouseistobreakdownlargechunksofproductandredistributeitinsmallerquantities.Ingeneral,thesmallerthehandlingunit,thegreaterthehandlingcost.,仓库作业具体而言，包括以下两大部分：InboundprocessesReceiving收货Put-away放置OutboundprocessesOrder-picking分拣Checking,packing,shipping,第三章：仓库作业Warehouseoperations,仓库作业的原则尽可能减少停顿保持可视化,第三章：仓库作业Warehouseoperations,Receiving（收货）作业的特点Receivingmaybeginwithadvancenotificationofthearrivalofgoods.Thisallowsthewarehousetoschedulereceiptandunloadingtocoordinateefficientlywithotheractivitieswithinthewarehouse.伴随接收的可能有检验,扫描输入数据库等.人力需求不高对配送中心而言，大约仅占其运作成本的10%左右,第三章：仓库作业Warehouseoperations,Put-away（放置）作业在物品摆放到货架之前，必须决定好其合适的存储地点并将该信息输入系统需要较多的人力成本对配送中心而言，大约仅占其运作成本的15%左右,第三章：仓库作业Warehouseoperations,Order-picking分拣与其它作业相比，与信息系统的结合更紧密Order-picking与收货不同,前者是被动的少量的.而后者是可能事先知道故做了相关准备且是大批的.故前者更费时间.另外,随着生命周期越来越短,对拣货的时间要求越来越快.,第三章：仓库作业Warehouseoperations,分拣大约仅占仓库运作成本的55%左右，分拣成本进一步可分解为以下各部分,第三章：仓库作业Warehouseoperations,Order-picking对不同物品的分拣成本是不同的。提高分拣效率的方法storingthemostpopularskustogetherbatchorders合并订单进行分拣,第三章：仓库作业Warehouseoperations,是否应合并订单进行分拣取决于订单结构single-lineordersVerylargeordersIntermediate-sizeorders注意,BatchingPicking可能会减少Responsiveness,因为还需再次分拣,第三章：仓库作业Warehouseoperations,分拣的其它问题分拣工人的合作分拣问题可分为product-to-picker与Picker-to-product,第三章：仓库作业Warehouseoperations,Checkingandpacking对人力需求大LittleWalking保证订单准确性，避免错发货对客户的订单尽可能提高包装的容积率,第三章：仓库作业Warehouseoperations,总结Mostoftheexpenseinatypicalwarehouseisinlabor;mostofthatisinorder-picking;andmostofthatisintravel.仓库的其它作业handlereturnslabelingPostponementoffinalassemblyInvoicing,第三章：仓库作业Warehouseoperations,确定仓库需要的月台（DOCK）的数量nD=dt/qT仓库容量的决定(以托盘的数量为计算单位)1:Dedicatedstoragepolicy2:Randomstoragepolicy3:Class-basedstoragepolicy计算实例计算储存区的长宽高高是由储存的技术来决定的(如叉车最高能多高,如是人力的话最高能多高)长与宽的决定LxLyNxNy计算实例,第六章仓储规划,确定仓库需要的月台（泊位）数量,确定仓库需要的月台（泊位）数量,仓库容量的决定,Theareaofthestoragezonemustbelargeenoughtoaccommodategoodsinpeakperiods.Ontheotherhand,ifthestoragezoneexceedstherealneedsofthefirm,storageandretrievaltimesbecomeuselesslyhigh.Thiscouldreducethethroughputorincreasematerialhandlingcost.,计算储存区的长宽高,计算储存区的长宽高,计算储存区的长宽高,计算储存区的长宽高,计算储存区的长宽高,计算储存区的长宽高,第六章仓库内部规划,因而，为了最小化行走成本（Travelcost):将所有的库位按照di从小到大进行排序将所有的物品按周转速度从大到小进行排序Movedownthelist,assigningthepalletsofthenextfastest-turningskustothenextbestlocationsavailable.,第六章仓库内部规划,第六章仓库内部规划-确定收货与发货区的位置,第六章仓库内部规划-确定收货与发货区的位置,哪种更好?取决于流入流出仓库物品的总体结构Iftherewillbeasmallamountofveryfast-movingskus,itmaybemoreefficienttoputreceivingandshippingonthesamesideofthefacility,becausethesavingsfromthefewveryconvenientlocationsmayoffsetanylossduetothegreaternumberoflessconvenientlocations.,第六章仓库内部规划,第一种：贯通式Flow-throughconfiguration,这两种规划各自的特点characteristicsofeachtypeoflayout:,第一种：贯通式收发货区位于仓库的两侧使得很多存储库位处于同等便利的位置保守设计:Morereasonablyconvenientstoragelocations但很少的库位处于非常便利的位置更适合于流量非常大的仓库适合于仓库长而狭窄时的情形Limitsopportunityforefficienciesbydualtransactions,两种规划各自的特点,第二种：U-形设计,这两种规划各自的特点characteristicsofeachtypeoflayout:,第二种：U-形设计收发货区位于库房的同侧Makesthemostconvenientlocationsstillmoreconvenient,lessconvenientlocationsevenworse.适合于当物品的周转速度呈现较强的ABC特点时的情形提高了收发货区使用的效率及柔性提高了叉车的使用效率节省了库房前道路的投资费用Allowsexpansionalongotherthreesidesofwarehouse.,这两种规划各自的特点characteristicsofeachtypeoflayout:,仓库货区的其它的规划方式,提高仓库容积利用率的两种方法:利用托盘货架增加堆垛的高度Palletsthatcanbestackedhighallowmanypalletpositionspersquarefootoffloorspace.Conversely,palletsthatareunusuallyheavyorfragileorthathaveuneventopsurfacescannotbestackedveryhighandsorenderunusableallthespaceabove.Thiswastemaybeavoidedbyinstallingpalletrack（货架）,sothatpalletsmaybestoredindependentlyofeachother.,第六章仓库内部规划,它能使存放的物品更易存取，因而能够减少人力。如下图：,第六章仓库内部规划,储存货架的深度Lanedepth,储存货架的深度Lanedepth,这里存在着背反:Thesingle-deeplayouthaseightaislesandprovides196palletstoragelocations,allofwhicharedirectlyaccessible,whichmeansthattheyareavailableforreassignmentassoonasthecurrentpalletisshippedout.Incontrast,thedouble-deeplayouthasonlysixaislesandprovides280palletstoragelocationsbutonly140ofthemaredirectlyaccessible.因而：更深的货架能够产生更多的库位但其价值是递减的。,储存货架的深度Lanedepth,对单个物品的分拣是库房操作中最费人力的作业，因为其操作对象为最小的单位。Warehousesthat,20yearsago,mighthaveshippedcartonstocustomersnowshippiecesandmuchmorefrequently.Theimportanceofpiece-pickinghasgreatlyincreasedbecauseofpressurestoreduceinventorywhileexpandingproductlines.为了提高分拣效率，库房应该考虑的是将储存作业（区域）与分拣作业（区域）分开。,快速分拣区的设计Designofafastpickarea,什么是快速分拣区Aseparatepickingarea,sometimescalledafast-pickorforwardpickorprimarypickarea,isasub-regionofthewarehouseinwhichoneconcentratespicksandorderswithinasmallphysicalspace.快速分拣区一般采用固定库位的方式,快速分拣区的设计Designofafastpickarea,设置快速分拣区的好处:Manyofthemostpopularstockkeepingunits(skus)arestoredthereinrelativelysmallamounts,sothatmostpickingcanbeaccomplishedwithinarelativelysmallarea.Thismeansthatpickersdolessunproductivetravelandmaybemoreeasilysupervised.Reducedpickcostsandincreasedresponsivenesstocustomerdemand.弊端：需要不断从存储区域补货,快速分拣区的设计,设计快速分拣区要考虑的基本问题:哪些SKUs应放在快速分拣区？以及每一种sku放多少，空间多大估算补货成本补货的成本取决于以下因素Thenumberoftimestheskurequiresreplenishment.Thenumberofstorageunitstobereplenished.,快速分拣区的设计Designofafastpickarea,为简单起见，我们假设补货的成本仅与补货的次数有关，这与现实是近似的。补货次数的估计Ifskuiflowsthroughthewarehouseatrateficubicfeetperyearthenwecanestimatethatskuiwillrequireabout其中:fi=viisthevolumecubic-feetofskuistoredinthefast-pickarea.,快速分拣区的设计Designofafastpickarea,快速分拣区的设计Designofafastpickarea,令V为快速分拣区的总容量，我们的问题为：不失一般性，我们仅考虑两种AandB.则问题为将第一个约束条件用等式vA+vB=V代替并代入到目标函数。,快速分拣区的设计Allocatingspaceinthefast-pickarea,目标函数变为对VB微分求一阶条件，我们得到:更一般化,我们有以下结论：,快速分拣区的设计Designofafastpickarea,该结论显示：分配给某SKU的最优存储空间不仅取决于自己的流动速度fi，而且还取决于所有其它SKU的流动速度进一步，我们有以下推论：,快速分拣区的设计,现实中两种通常使用的快速分拣区存储空间的分配方法等空间分配（EqualSpaceAllocation）:Allocatesthesameamountofspacetoeachsku,sothat,ifVcubicfeetareavailable,vi=V/nandskuiisrestockednfi/Vtimesayear.等时间分配（EqualTimeAllocation）:storesanequaltimesupplyofeachsku,sothatvi/fi=vj/fj.,快速分拣区的设计,定理:无论为等空间分配还是等时间分配，所需要的补货次数是一样的，相应地，两种方式所产生的总补货成本也相同。,快速分拣区的设计,例：考虑分拣区总空间为1，两个SKUA与B其fi分别为16与1，则两种不同的空间分配方式的结果如下：,快速分拣区的设计,结论:各SKU流速f的差异越大，则使用最优的空间分配方法所减少的补货次数越多，进而对减少总补货成本的效果越明显。比如:6,000fast-movingskusofamajordrugstorechain;EqualTimeAllocationsrequirealmost50%morerestocksthanoptimum.Withover100order-pickersand20re-stockers,thissuggeststhatonlyabout70order-pickersand14re-stockerswerenecessary,whichmeansasignificantdirectsavingsinlabor.,快速分拣区的设计,进一步，有如下定理：Theorem(“LawofUniformRestocking”)UnderOptimalAllocationseachunitofstoragespacewillberestockedatthesamefrequency.,快速分拣区的设计,按组存储（Storagebyfamily）将相关物品存放在一起的原因：Togetgoodspaceutilization,productofsimilarsizesorshapesmightbestoredtogether.Tosimplifyput-away,productmightbestoredbyvendorsothatallproductarrivingonatruckgoestothesameregionofthewarehouse.Productmaybegroupedbysecurityrequirements.,快速分拣区的设计的其它问题,Slottingreferstothecarefulplacementofindividualcases/pieceswithinthewarehouse/cases.Itmaybethoughtofaslayoutinthesmall.Slotting的目标包括：在给定的空间装入更多的物品通过将周转速度快或较重的物品放在合适的位置比如waistlevel来提高人体工程学的效率。,仓库规划-微观Pieces:Geometryofslotting装箱,装箱(Packing)问题:有三类One-dimension仅考虑重量,对那些密度很高的物品如钢材Two-dimensionThree-dimensionNP-hard故一般用算法.,仓库规划-微观Pieces:Geometryofslotting装箱,直接转运站台是高速的仓库（Crossdocksarehighspeedwarehouses）.如果一个到达的物品已经有了最终的需求，那么就没有必要进行存储而应该直接从收货区运到发货区。这样该物品经过该仓库的速度就加快了，这样仓库操作的人力成本就大大减少了。Inahigh-volumecrossdocktheturnovertimesmaybemeasuredinhours.Tosupportthisvelocityofmovement,acrossdockmaybenothingmorethanaslabofconcretewitharoofandwallspunctuatedwithdoorsfortrailers.Freightispulledoffarrivingtrailers,sortedandloadedontodepartingtrailerswithoutintermediatestorage.,直接转运（Cross-docking）,为什么直接转运?Thebiggestreasontohaveacrossdockistoreducetransportationcosts.Thiscanbeachievedbyconsolidatingmultipleshipmentssothatfulltruckloadscanbesent。,直接转运的原因,一般而言，卸货比装货要容易，通常后者所花的时间是前者的两倍。为了使物品流动的更通畅，流入流出直接转运站台的容量应该合理设计。比如,oneshouldplantohavetwiceasmanyoutgoingdoorsasincomingdoors.Alternatively,onecanbalancetheratesofflowbyassignmentorworkers.Moredoorsnotnecessarilymeansefficiency,rather,thelongdistancemayincreasethetraveltimeandtheconsequentlythelaborcost.,直接转运中心的设计,北美massconsumption.allowsfewer,morecentralizedandthereforelargerdistributioncenters.,世界各地的仓库简介（Warehousingaroundtheworld）,东亚Themostactiveeconomicareasareseparatedbylotsofwater,whichmeanslotsofproductconveyedbyair(forhigh-valueortime-sensitiveproducts)orship(forbulkyitemsorcommodities).Forbothairandseacargo,thelargefixedcostsincreaseincentivestoconsolidatefreightConsequently,oneexpectstoseetheemergenceofstrongregionalhubs,suchasSingaporeandHongKong,tosupportthisconsolidation.,世界各地的仓库简介（Warehousingaroundtheworld）,印度IndiaCapitalcostsarerelativelyhighinrelationtothecostoflaborandsothereislesspressuretoinstallspecializedstorage,evenpalletrack.Andbecauselaborcostsarelowthereislessincentivetoincreaseefficiency.Forexample,itisnotanattractivepropositiontoreducelaborcostsbypickingfromflowrack:Thelaborsavingscannotjustifythecostoftherackortheforklifttrucks.,世界各地的仓库简介（Warehousingaroundtheworld）,Inaddition,warehousesinIndiadistributemainlytothelocaleconomyandsosupplyamarketthatisnotwealthy.Consequently,theskusarenotlikelytobehighcostitemsandsothereisnotmuchsavingsavailablefromreducinginventoriesbyprecisetiming.Consequentlyinformationtechnologiescannotgeneratemuchsavings.Finally,inefficienciesintransportmakeIndiaineffectacollectionofsmallermarkets.Theseinefficienciesincludethephysical,suchasroadsinless-than-idealcondition,aswellastheadministrative.,世界各地的仓库简介（Warehousingaroundtheworld）,Forexample,eachstatewithinIndialeviescustomsdutiesonfreighttransportedacrosstheborder(differentfromChina).Thisslowsinterstatecommerceandincreasestheexpense.Suchfactorsincreasethecostsoftransportationandsofavorastrategyofhavingmore,smallerdistributioncentersratherthanfewer,largerones,wherethevolumeofactivitycouldbetterjustifycapitalinvestment,世界各地的仓库简介（Warehousingaroundtheworld）,ChinaAdistinctivefeatureofthelogisticssceneinChinaistheseeminglyboundlesssupplyofverylowcostoflabortogetherwithrelativelyinexpensiveland.Consequentlywarehousestendtobelarge,lowbuildingsasinNorthAmerica;butwithsomestrikingdifferences.,合适的就是最好的,世界各地的仓库简介（Warehousingaroundtheworld）,Despitecheaplabor,Chinadoeshavesomecapital-intensivewarehouses,withthelatestinformationtechnologyandstorageequipment.Suchwarehousesaremostlikelydevotedtothedistributionofhigh-valuegoodsforexport