1、Warehouse ScienceE-mail:1第一章 Warehouse rationale倉庫是什么？Warehouses are the points in the supply chain where product pauses, however briefly, and is touched.為什么需要倉庫？To better match supply with customer demand:demand can change quickly, but supply takes longer to change.Warehouses can also buffer agains

2、t sudden changes in supply. To consolidate productTo provide value-added processing2倉庫分類While there are many types of warehouses in the supply chain, there is a systematic way to think about a warehouse system regardless of the industry in which it operates.第一章 Warehouse rationale3第二章 Material flow什

3、么是供應(yīng)鏈？The “supply chain” is the sequence of processes through which product moves from its origin toward the customer. Pipeline 與incompressible fluid model流體模型4流體模型對我們的啟發(fā):Keep the product moving; avoid starts and stops, which mean extra handling and additional space requirements.Avoid layouts that i

4、mpede smooth flow.Identify and resolve bottlenecks to flow.流體模型與JIT的關(guān)系該模型是對現(xiàn)實的一種近似第二章 Material flow56庫位固定庫位： The simplest is dedicated storage, in which each location is reserved for an assigned product and only that product may be stored there.固定庫位的好處（Pros）Because the locations of products do not c

5、hange, more popular items can be stored in more convenient locations and workers can learn the layout, all of which makes order-picking more efficient.第二章 Material flow 庫位：固定庫位與共享庫位Storage: “Dedicated” versus “Shared”7固定庫位的缺點（Cons)：The problem with dedicated storage is that it does not use space eff

6、iciently.共享庫位第二章 Material flow 庫位：固定庫位與共享庫位Storage: “Dedicated” versus “Shared”8共享庫位的缺點：需要倉庫管理信息系統(tǒng)的支持工人操作時間成本及復(fù)雜性增加怎么辦？第二章 Material flow 庫位：固定庫位與共享庫位Storage: “Dedicated” versus “Shared”9共享庫位對提高倉庫存儲空間利用率的測算How much improvement in space utilization is possible with shared storage?考慮一種產(chǎn)品，兩周的需求量，存儲在兩個相等

7、大小的庫位上且需求速率恒定的情形空間利用率=平均庫存/平均所需存儲空間第二章 Material flow 庫位：固定庫位與共享庫位Storage: “Dedicated” versus “Shared”10第三章：倉庫作業(yè) Warehouse operations倉庫作業(yè)的總體特點：A warehouse reorganizes and repackages product. Product typically arrives packaged on a larger scale and leaves packaged on a smaller scale. In other words, a

8、n important function of this warehouse is to break down large chunks of product and redistribute it in smaller quantities.In general, the smaller the handling unit, the greater the handling cost. 11倉庫作業(yè)具體而言，包括以下兩大部分：Inbound processesReceiving 收貨Put-away 放置Outbound processesOrder-picking 分揀Checking,

9、packing, shipping 第三章：倉庫作業(yè) Warehouse operations12倉庫作業(yè)的原則盡可能減少停頓保持可視化第三章：倉庫作業(yè) Warehouse operations13Receiving（收貨）作業(yè)的特點Receiving may begin with advance notification of the arrival of goods. This allows the warehouse to schedule receipt and unloading to coordinate efficiently with other activities with

10、in the warehouse.伴隨接收的可能有檢驗,掃描輸入數(shù)據(jù)庫等.人力需求不高對配送中心而言，大約僅占其運(yùn)作成本的10%左右第三章：倉庫作業(yè) Warehouse operations14Put-away（放置）作業(yè)在物品擺放到貨架之前，必須決定好其合適的存儲地點并將該信息輸入系統(tǒng)需要較多的人力成本對配送中心而言，大約僅占其運(yùn)作成本的15%左右第三章：倉庫作業(yè) Warehouse operations15Order-picking分揀與其它作業(yè)相比，與信息系統(tǒng)的結(jié)合更緊密Order-picking 與收貨不同,前者是被動的少量的.而后者是可能事先知道故做了相關(guān)準(zhǔn)備且是大批的.故前者更費時

11、間.另外,隨著生命周期越來越短,對揀貨的時間要求越來越快.第三章：倉庫作業(yè) Warehouse operations16分揀大約僅占倉庫運(yùn)作成本的55%左右，分揀成本進(jìn)一步可分解為以下各部分第三章：倉庫作業(yè) Warehouse operations17Order-picking對不同物品的分揀成本是不同的。提高分揀效率的方法storing the most popular skus togetherbatch orders 合并訂單進(jìn)行分揀第三章：倉庫作業(yè) Warehouse operations18是否應(yīng)合并訂單進(jìn)行分揀取決于訂單結(jié)構(gòu)single-line ordersVery large

12、orders Intermediate-size orders 注意,Batching Picking可能會減少Responsiveness, 因為還需再次分揀第三章：倉庫作業(yè) Warehouse operations19分揀的其它問題分揀工人的合作分揀問題可分為product-to-picker 與Picker-to-product第三章：倉庫作業(yè) Warehouse operations20Checking and packing對人力需求大Little Walking保證訂單準(zhǔn)確性，避免錯發(fā)貨對客戶的訂單盡可能提高包裝的容積率第三章：倉庫作業(yè) Warehouse operations21

13、總結(jié)Most of the expense in a typical warehouse is in labor; most of that is in order-picking; and most of that is in travel.倉庫的其它作業(yè)handle returnslabelingPostponement of final assemblyInvoicing第三章：倉庫作業(yè) Warehouse operations22確定倉庫需要的月臺（DOCK） 的數(shù)量nD=dt/qT倉庫容量的決定 (以托盤的數(shù)量為計算單位)1:Dedicated storage policy2:Ran

14、dom storage policy3:Class-based storage policy計算實例計算儲存區(qū)的長寬高高是由儲存的技術(shù)來決定的(如叉車最高能多高,如是人力的話最高能多高)長與寬的決定 Lx Ly Nx Ny 計算實例第六章 倉儲規(guī)劃23確定倉庫需要的月臺（泊位）數(shù)量24確定倉庫需要的月臺（泊位）數(shù)量25倉庫容量的決定The area of the storage zone must be large enough to accommodate goods in peak periods. On the other hand, if the storage zone exceed

15、s the real needs of the firm, storage and retrieval times become uselessly high. This could reduce the throughput or increase material handling cost.26272829計算儲存區(qū)的長寬高30計算儲存區(qū)的長寬高31計算儲存區(qū)的長寬高32計算儲存區(qū)的長寬高3334計算儲存區(qū)的長寬高35計算儲存區(qū)的長寬高36第六章 倉庫內(nèi)部規(guī)劃37因而，為了最小化行走成本（Travel cost) :將所有的庫位按照di 從小到大進(jìn)行排序?qū)⑺械奈锲钒粗苻D(zhuǎn)速度從大到小進(jìn)行

16、排序Move down the list, assigning the pallets of the next fastest-turning skus to the next best locations available.第六章 倉庫內(nèi)部規(guī)劃38第六章 倉庫內(nèi)部規(guī)劃-確定收貨與發(fā)貨區(qū)的位置39第六章 倉庫內(nèi)部規(guī)劃-確定收貨與發(fā)貨區(qū)的位置40哪種更好?取決于流入流出倉庫物品的總體結(jié)構(gòu)If there will be a small amount of very fast-moving skus, it may be more efficient to put receiving and s

17、hipping on the same side of the facility, because the savings from the few very convenient locations may offset any loss due to the greater number of less convenient locations.第六章 倉庫內(nèi)部規(guī)劃41第一種：貫通式Flow-through configuration這兩種規(guī)劃各自的特點characteristics of each type of layout:42第一種：貫通式收發(fā)貨區(qū)位于倉庫的兩側(cè)使得很多存儲庫位處于

18、同等便利的位置保守設(shè)計: More reasonably convenient storage locations但很少的庫位處于非常便利的位置更適合于流量非常大的倉庫適合于倉庫長而狹窄時的情形Limits opportunity for efficiencies by dual transactions兩種規(guī)劃各自的特點43第二種： U-形設(shè)計這兩種規(guī)劃各自的特點characteristics of each type of layout:44第二種：U-形設(shè)計收發(fā)貨區(qū)位于庫房的同側(cè)Makes the most convenient locations still more convenie

19、nt, less convenient locations even worse.適合于當(dāng)物品的周轉(zhuǎn)速度呈現(xiàn)較強(qiáng)的ABC特點時的情形提高了收發(fā)貨區(qū)使用的效率及柔性提高了叉車的使用效率節(jié)省了庫房前道路的投資費用Allows expansion along other three sides of warehouse.這兩種規(guī)劃各自的特點characteristics of each type of layout:45倉庫貨區(qū)的其它的規(guī)劃方式46提高倉庫容積利用率的兩種方法 : 利用托盤貨架增加堆垛的高度Pallets that can be stacked high allow many pal

20、let positions per square foot of floor space. Conversely, pallets that are unusually heavy or fragile or that have uneven top surfaces cannot be stacked very high and so render unusable all the space above. This waste may be avoided by installing pallet rack（貨架）, so that pallets may be stored indepe

21、ndently of each other.第六章 倉庫內(nèi)部規(guī)劃47它能使存放的物品更易存取，因而能夠減少人力。如下圖：第六章 倉庫內(nèi)部規(guī)劃48儲存貨架的深度Lane depth49儲存貨架的深度Lane depth50這里存在著背反: The single-deep layout has eight aisles and provides 196 pallet storage locations, all of which are directly accessible, which means that they are available for reassignment as soon

22、 as the current pallet is shipped out. In contrast, the double-deep layout has only six aisles and provides 280 pallet storage locationsbut only 140 of them are directly accessible.因而：更深的貨架能夠產(chǎn)生更多的庫位但其價值是遞減的。儲存貨架的深度Lane depth51對單個物品的分揀是庫房操作中最費人力的作業(yè)，因為其操作對象為最小的單位。Warehouses that, 20 years ago, might h

23、ave shipped cartons to customers now ship pieces and much more frequently.The importance of piece-picking has greatly increased because of pressures to reduce inventory while expanding product lines.為了提高分揀效率，庫房應(yīng)該考慮的是將儲存作業(yè)（區(qū)域）與分揀作業(yè)（區(qū)域）分開。快速分揀區(qū)的設(shè)計Design of a fast pick area5253什么是快速分揀區(qū)A separate pickin

24、g area, sometimes called a fast-pick or forward pick or primary pick area, is a sub-region of the warehouse in which one concentrates picks and orders within a small physical space.快速分揀區(qū)一般采用固定庫位的方式快速分揀區(qū)的設(shè)計Design of a fast pick area54設(shè)置快速分揀區(qū)的好處:Many of the most popular stock keeping units (skus) are

25、stored there in relatively small amounts, so that most picking can be accomplished within a relatively small area.This means that pickers do less unproductive travel and may be more easily supervised.Reduced pick costs and increased responsiveness to customer demand.弊端：需要不斷從存儲區(qū)域補(bǔ)貨快速分揀區(qū)的設(shè)計55設(shè)計快速分揀區(qū)要考

26、慮的基本問題:哪些SKUs應(yīng)放在快速分揀區(qū)？以及每一種sku 放多少，空間多大估算補(bǔ)貨成本補(bǔ)貨的成本取決于以下因素The number of times the sku requires replenishment.The number of storage units to be replenished.快速分揀區(qū)的設(shè)計Design of a fast pick area56為簡單起見，我們假設(shè)補(bǔ)貨的成本僅與補(bǔ)貨的次數(shù)有關(guān)，這與現(xiàn)實是近似的。補(bǔ)貨次數(shù)的估計If sku i flows through the warehouse at rate fi cubic feet per year t

27、hen we can estimate that sku i will require about 其中:fi=vi is the volume cubic-feet of sku i stored in the fast-pick area.快速分揀區(qū)的設(shè)計Design of a fast pick area57快速分揀區(qū)的設(shè)計Design of a fast pick area58令 V 為快速分揀區(qū)的總?cè)萘浚覀兊膯栴}為：不失一般性，我們僅考慮兩種A and B. 則問題為將第一個約束條件用等式vA+vB = V代替并代入到目標(biāo)函數(shù)。快速分揀區(qū)的設(shè)計Allocating space in

28、 the fast-pick area59目標(biāo)函數(shù)變?yōu)閷B微分求一階條件，我們得到:更一般化,我們有以下結(jié)論：快速分揀區(qū)的設(shè)計Design of a fast pick area60該結(jié)論顯示：分配給某SKU的最優(yōu)存儲空間不僅取決于自己的流動速度 fi ，而且還取決于所有其它SKU的流動速度進(jìn)一步，我們有以下推論：快速分揀區(qū)的設(shè)計61現(xiàn)實中兩種通常使用的快速分揀區(qū)存儲空間的分配方法等空間分配（Equal Space Allocation）: Allocates the same amount of space to each sku, so that, if V cubic feet are

29、 available, vi = V/n and sku i is restocked nfi/V times a year.等時間分配（Equal Time Allocation）: stores an equal time supply of each sku, so that vi/fi = vj/fj .快速分揀區(qū)的設(shè)計62定理:無論為等空間分配還是等時間分配，所需要的補(bǔ)貨次數(shù)是一樣的，相應(yīng)地，兩種方式所產(chǎn)生的總補(bǔ)貨成本也相同。快速分揀區(qū)的設(shè)計63例：考慮分揀區(qū)總空間為1，兩個SKU A 與 B 其fi 分別為16與1，則兩種不同的空間分配方式的結(jié)果如下： 快速分揀區(qū)的設(shè)計64結(jié)論:

30、各SKU流速f的差異越大，則使用最優(yōu)的空間分配方法所減少的補(bǔ)貨次數(shù)越多，進(jìn)而對減少總補(bǔ)貨成本的效果越明顯。比如: 6,000 fast-moving skus of a major drug store chain; Equal Time Allocations require almost 50% more restocks than optimum. With over 100 order-pickers and 20 re-stockers, this suggests that only about 70 order-pickers and 14 re-stockers were ne

31、cessary, which means a significant direct savings in labor.快速分揀區(qū)的設(shè)計65進(jìn)一步，有如下定理：Theorem (“Law of Uniform Restocking”) Under Optimal Allocations each unit of storage space will be restocked at the same frequency.快速分揀區(qū)的設(shè)計66按組存儲（Storage by family）將相關(guān)物品存放在一起的原因：To get good space utilization, product of s

32、imilar sizes or shapes might be stored together.To simplify put-away, product might be stored by vendor so that all product arriving on a truck goes to the same region of the warehouse.Product may be grouped by security requirements.快速分揀區(qū)的設(shè)計的其它問題67Slotting refers to the careful placement of individu

33、al cases/ pieces within the warehouse/cases. It may be thought of as layout in the small.Slotting 的目標(biāo)包括：在給定的空間裝入更多的物品通過將周轉(zhuǎn)速度快或較重的物品放在合適的位置比如waist level來提高人體工程學(xué)的效率。倉庫規(guī)劃-微觀Pieces: Geometry of slotting裝箱68裝箱(Packing)問題:有三類One-dimension 僅考慮重量, 對那些密度很高的物品如鋼材Two-dimensionThree-dimensionNP-hard 故一般用算法.倉庫規(guī)劃

34、-微觀Pieces: Geometry of slotting裝箱69直接轉(zhuǎn)運(yùn)站臺是高速的倉庫（Crossdocks are high speed warehouses）.如果一個到達(dá)的物品已經(jīng)有了最終的需求，那么就沒有必要進(jìn)行存儲而應(yīng)該直接從收貨區(qū)運(yùn)到發(fā)貨區(qū)。這樣該物品經(jīng)過該倉庫的速度就加快了，這樣倉庫操作的人力成本就大大減少了。In a high-volume crossdock the turnover times may be measured in hours. To support this velocity of movement, a crossdock may be noth

35、ing more than a slab of concrete with a roof and walls punctuated with doors for trailers. Freight is pulled off arriving trailers, sorted and loaded onto departing trailers without intermediate storage.直接轉(zhuǎn)運(yùn)（Cross-docking）70為什么直接轉(zhuǎn)運(yùn)?The biggest reason to have a crossdock is to reduce transportation c

36、osts. This can be achieved by consolidating multiple shipments so that full truck loads can be sent 。直接轉(zhuǎn)運(yùn)的原因71一般而言，卸貨比裝貨要容易，通常后者所花的時間是前者的兩倍。為了使物品流動的更通暢，流入流出直接轉(zhuǎn)運(yùn)站臺的容量應(yīng)該合理設(shè)計。比如, one should plan to have twice as many outgoing doors as incoming doors. Alternatively, one can balance the rates of flow by

37、assignment or workers.More doors not necessarily means efficiency, rather, the long distance may increase the travel time and the consequently the labor cost.直接轉(zhuǎn)運(yùn)中心的設(shè)計72北美m(xù)ass consumption. allows fewer, more centralized and therefore larger distribution centers. 世界各地的倉庫簡介（Warehousing around the worl

38、d）73東亞The most active economic areas are separated by lots of water, which means lots of product conveyed by air (for high-value or time-sensitive products) or ship (for bulky items or commodities). For both air and sea cargo, the large fixed costs increase incentives to consolidate freight Conseque

39、ntly, one expects to see the emergence of strong regional hubs, such as Singapore and Hong Kong, to support this consolidation.世界各地的倉庫簡介（Warehousing around the world）74印度IndiaCapital costs are relatively high in relation to the cost of labor and so there is less pressure to install specialized stora

40、ge, even pallet rack. And because labor costs are low there is less incentive to increase efficiency. For example, it is not an attractive proposition to reduce labor costs by picking from flow rack: The labor savings cannot justify the cost of the rack or the forklift trucks.世界各地的倉庫簡介（Warehousing a

41、round the world）75In addition, warehouses in India distribute mainly to the local economy and so supply a market that is not wealthy. Consequently, the skus are not likely to be high cost items and so there is not much savings available from reducing inventories by precise timing. Consequently infor

42、mation technologies cannot generate much savings.Finally, inefficiencies in transport make India in effect a collection of smaller markets. These inefficiencies include the physical, such as roads in less-than-ideal condition, as well as the administrative.世界各地的倉庫簡介（Warehousing around the world）76Fo

43、r example, each state within India levies customs duties on freight transported across the border (different from China). This slows interstate commerce and increases the expense. Such factors increase the costs of transportation and so favor a strategy of having more, smaller distribution centers r

44、ather than fewer, larger ones, where the volume of activity could better justify capital investment世界各地的倉庫簡介（Warehousing around the world）77ChinaA distinctive feature of the logistics scene in China is the seemingly boundless supply of very low cost of labor together with relatively inexpensive land

45、.Consequently warehouses tend to be large, low buildings as in North America; but with some striking differences.合適的就是最好的世界各地的倉庫簡介（Warehousing around the world）78Despite cheap labor, China does have some capital-intensive warehouses, with the latest information technology and storage equipment. Such warehouses are most likely devoted to the distribution of high-value goods for export. Because such goods, such as consumer electroni