仓库管理系统 毕业论文外文翻译.doc

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1、仓库管理系统 毕业论文外文翻译 Warehouse Management Systems WMS. The evolution of warehouse management systems WMS is very similar to that of many other software solutionsInitially a system to control movement and storage of materials within a warehouse, the role of WMS is expanding to including light manufacturin

2、g, transportation management, order management, and complete accounting systemsTo use the grandfather of operations-related software, MRP, as a comparison, material requirements planning MRP started as a system for planning raw material requirements in a manufacturing environmentSoon MRP evolved int

3、o manufacturing resource planning MRPII, which took the basic MRP system and added scheduling and capacity planning logic. Eventually MRPII evolved into enterprise resource planning ERP, incorporating all the MRPII functionality with full financials and customer and vendor management functionalityNo

4、w, whether WMS evolving into a warehouse-focused ERP system is a good thing or not is up to debateWhat is clear is that the expansion of the overlap in functionality between Warehouse Management Systems, Enterprise Resource Planning, Distribution Requirements Planning, Transportation Management Syst

5、ems, Supply Chain Planning, Advanced Planning and Scheduling, and Manufacturing Execution Systems will only increase the level of confusion among companies looking for software solutions for their operations Even though WMS continues to gain added functionality, the initial core functionality of a W

6、MS has not really changedThe primary purpose of a WMS is to control the movement and storage of materials within an operation and process the associated transactionsDirected picking, directed replenishment, and directed put away are the key to WMSThe detailed setup and processing within a WMS can va

7、ry significantly from one software vendor to another, however the basic logic will use a combination of item, location, quantity, unit of measure, and order information to determine where to stock, where to pick, and in what sequence to perform these operations At a bare minimum, a WMS should: Have

8、a flexible location system. Utilize user-defined parameters to direct warehouse tasks and use live documents to execute these tasks. Have some built-in level of integration with data collection devices. Do You Really Need WMS? Not every warehouse needs a WMSCertainly any warehouse could benefit from

9、 some of the functionality but is the benefit great enough to justify the initial and ongoing costs associated with WMSWarehouse Management Systems are big, complex, data intensive, applicationsThey tend to require a lot of initial setup, a lot of system resources to run, and a lot of ongoing data m

10、anagement to continue to runThats right, you need to manage your warehouse management systemOften times, large operations will end up creating a new IS department with the sole responsibility of managing the WMSThe Reality: The implementation of a WMS along with automated data collection will likely

11、 give you increases in accuracy, reduction in labor costs provided the labor required to maintain the system is less than the labor saved on the warehouse floor, and a greater ability to service the customer by reducing cycle timesExpectations of inventory reduction and increased storage capacity ar

12、e less likelyWhile increased accuracy and efficiencies in the receiving process may reduce the level of safety stock required, the impact of this reduction will likely be negligible in comparison to overall inventory levels. The predominant factors that control inventory levels are lot sizing, lead

13、times, and demand variabilityIt is unlikely that a WMS will have a significant impact on any of these factors. And while a WMS certainly provides the tools for more organized storage which may result in increased storage capacity, this improvement will be relative to just how sloppy your pre-WMS pro

14、cesses were Beyond labor efficiencies, the determining factors in deciding to implement a WMS tend to be more often associated with the need to do something to service your customers that your current system does not support or does not support well such as first-in-first-out, cross-docking, automat

15、ed pick replenishment, wave picking, lot tracking, yard management, automated data collection, automated material handling equipment, etc.Setup The setup requirements of WMS can be extensive. The characteristics of each item and location must be maintained either at the detail level or by grouping s

16、imilar items and locations into categoriesAn example of item characteristics at the detail level would include exact dimensions and weight of each item in each unit of measure the item is stocked each, cases, pallets, etc as well as information such as whether it can be mixed with other items in a l

17、ocation, whether it is rack able, stack height, quantity per location, hazard classifications, finished goods or raw material, fast versus slow mover, etcAlthough some operations will need to set up each item this way, most operations will benefit by creating groups of similar productsFor example, i

18、f you are a distributor of music CDs you would create groups for single CDs, and double CDs, maintaining the detailed dimension and weight information at the group level and only needing to attach the group code to each itemYou would likely need to maintain detailed information on special items such

19、 as boxed sets or CDs in special packagingYou would also create groups for the different types of locations within your warehouse. An example would be to create three different groups P1, P2, P3 for the three different sized forward picking locations you use for your CD pickingYou then set up the qu

20、antity of single CDs that will fit in a P1, P2, and P3 location, quantity of double CDs that fit in a P1, P2, P3 location etcYou would likely also be setting up case quantities, and pallet quantities of each CD group and quantities of cases and pallets per each reserve storage location group If this

21、 sounds simple, it iswell sort of. In reality most operations have a much more diverse product mix and will require much more system setupAnd setting up the physical characteristics of the product and locations is only part of the pictureYou have set up enough so that the system knows where a produc

22、t can fit and how many will fit in that locationYou now need to set up the information needed to let the system decide exactly which location to pick from, replenish from/to, and put away to, and in what sequence these events should occur remember WMS is all about “directed” movementYou do this by a

23、ssigning specific logic to the various combinations of item/order/quantity/location information that will occur Below I have listed some of the logic used in determining actual locations and sequences Location SequenceThis is the simplest logic; you simply define a flow through your warehouse and as

24、sign a sequence number to each locationIn order picking this is used to sequence your picks to flow through the warehouse, in put away the logic would look for the first location in the sequence in which the product would fit Zone LogicBy breaking down your storage locations into zones you can direc

25、t picking, put away, or replenishment to or from specific areas of your warehouseSince zone logic only designates an area, you will need to combine this with some other type of logic to determine exact location within the zone Fixed LocationLogic uses predetermined fixed locations per item in pickin

26、g, put away, and replenishmentFixed locations are most often used as the primary picking location in piece pick and case-pick operations, however, they can also be used for secondary storage Random LocationSince computers cannot be truly random nor would you want them to be the term random location

27、is a little misleadingRandom locations generally refer to areas where products are not stored in designated fixed locationsLike zone logic, you will need some additional logic to determine exact locations First-in-first-out FIFODirects picking from the oldest inventory first Last-in-first-out LIFOOp

28、posite of FIFO. I didnt think there were any real applications for this logic until a visitor to my site sent an email describing their operation that distributes perishable goods domestically and overseas. They use LIFO for their overseas customers because of longer in-transit times and FIFO for th

29、eir domestic customers Pick-to-clearLogic directs picking to the locations with the smallest quantities on handThis logic is great for space utilization Reserved LocationsThis is used when you want to predetermine specific locations to put away to or pick fromAn application for reserved locations wo

30、uld be cross-docking, where you may specify certain quantities of an inbound shipment be moved to specific outbound staging locations or directly to an awaiting outbound trailer imize CubeCube logic is found in most WMS systems however it is seldom usedCube logic basically uses unit dimensions to ca

31、lculate cube cubic inches per unit and then compares this to the cube capacity of the location to determine how much will fitNow if the units are capable of being stacked into the location in a manner that fills every cubic inch of space in the location, cube logic will workSince this rarely happens

32、 in the real world, cube logic tends to be impractical ConsolidateLooks to see if there is already a location with the same product stored in it with available capacityMay also create additional moves to consolidate like product stored in multiple locations Lot SequenceUsed for picking or replenishm

33、ent, this will use the lot number or lot date to determine locations to pick from or replenish from Its very common to combine multiple logic methods to determine the best locationFor example you may chose to use pick-to-clear logic within first-in-first-out logic when there are multiple locations w

34、ith the same receipt dateYou also may change the logic based upon current workloadDuring busy periods you may chose logic that optimizes productivity while during slower periods you switch to logic that optimizes space utilizationOther Functionality/Considerations Wave Picking/Batch Picking/Zone Pic

35、kingSupport for various picking methods varies from one system to anotherIn high-volume fulfillment operations, picking logic can be a critical factor in WMS selection. See my article on Order Picking for more info on these methods Task InterleavingTask interleaving describes functionality that mixe

36、s dissimilar tasks such as picking and put away to obtain imum productivityUsed primarily in full-pallet-load operations, task interleaving will direct a lift truck operator to put away a pallet on his/her way to the next pickIn large warehouses this can greatly reduce travel time, not only increasi

37、ng productivity, but also reducing wear on the lift trucks and saving on energy costs by reducing lift truck fuel consumption. Task interleaving is also used with cycle counting programs to coordinate a cycle count with a picking or put away task Integration with Automated Material Handling Equipmen

38、t If you are planning on using automated material handling equipment such as carousels, ASRS units, AGNS, pick-to-light systems, or separation systems, youll want to consider this during the software selection processSince these types of automation are very expensive and are usually a core component

39、 of your warehouse, you may find that the equipment will drive the selection of the WMSAs with automated data collection, you should be working closely with the equipment manufacturers during the software selection process Advanced Shipment Notifications ASNIf your vendors are capable of sending adv

40、anced shipment notifications preferably electronically and attaching compliance labels to the shipments you will want to make sure that the WMS can use this to automate your receiving process. In addition, if you have requirements to provide ASNs for customers, you will also want to verify this func

41、tionality Yard ManagementYard management describes the function of managing the contents inventory of trailers parked outside the warehouse, or the empty trailers themselvesYard management is generally associated with cross docking operations and may include the management of both inbound and outbou

42、nd trailers Labor Tracking/Capacity PlanningSome WMS systems provide functionality related to labor reporting and capacity planningAnyone that has worked in manufacturing should be familiar with this type of logicBasically, you set up standard labor hours and machine usually lift trucks hours per ta

43、sk and set the available labor and machine hours per shift. The WMS system will use this info to determine capacity and loadManufacturing has been using capacity planning for decades with mixed resultsThe need to factor in efficiency and utilization to determine rated capacity is an example of the s

44、hortcomings of this processNot that Im necessarily against capacity planning in warehousing, I just think most operations dont really need it and can avoid the disappointment of trying to make it workI am, however, a big advocate of labor tracking for individual productivity measurementMost WMS main

45、tain enough data to create productivity reportingSince productivity is measured differently from one operation to another you can assume you will have to do some minor modifications here usually in the form of custom reporting Integration with existing accounting/ERP systemsUnless the WMS vendor has

46、 already created a specific interface with your accounting/ERP system such as those provided by an approved business partner you can expect to spend some significant programming dollars hereWhile we are all hoping that integration issues will be magically resolved someday by a standardized interface

47、, we isnt there yetIdeally youll want an integrator that has already integrated the WMS you chose with the business software you are usingSince this is not always possible you at least want an integrator that is very familiar with one of the systems WMS + everything else As I mentioned at the beginn

48、ing of this article, a lot of other modules are being added to WMS packages. These would include full financials, light manufacturing, transportation management, purchasing, and sales order managementI dont see this as a unilateral move of WMS from an add-on module to a core system, but rather an op

49、tional approach that has applications in specific industries such as 3PLsUsing ERP systems as a point of reference, it is unlikely that this add-on functionality will match the functionality of best-of-breed applications available separatelyIf warehousing/distribution is your core business function and you dont want to have to deal with the integration issues of incorporating separate financials, order processing, etc. you may find