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Warehouse Management Systems (WMS).The evolution of warehouse management systems (WMS) is very similar to that of many other software solutions. Initially a system to control movement and storage of materials within a warehouse, the role of WMS is expanding to including light manufacturing, transportation management, order management, and complete accounting systems. To 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 environment. Soon MRP evolved into 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 functionality. Now, whether WMS evolving into a warehouse-focused ERP system is a good thing or not is up to debate. What is clear is that the expansion of the overlap in functionality between Warehouse Management Systems, Enterprise Resource Planning, Distribution Requirements Planning, Transportation Management Systems, 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 WMS has not really changed. The primary purpose of a WMS is to control the movement and storage of materials within an operation and process the associated transactions. Directed picking, directed replenishment, and directed put away are the key to WMS. The detailed setup and processing within a WMS can vary 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 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 WMS. Certainly any warehouse could benefit from some of the functionality but is the benefit great enough to justify the initial and ongoing costs associated with WMS? Warehouse Management Systems are big, complex, data intensive, applications. They tend to require a lot of initial setup, a lot of system resources to run, and a lot of ongoing data management to continue to run. Thats right, you need to manage your warehouse management system. Often times, large operations will end up creating a new IS department with the sole responsibility of managing the WMS. The Claims: WMS will reduce inventory! WMS will reduce labor costs! WMS will increase storage capacity! WMS will increase customer service! WMS will increase inventory accuracy! The Reality: The implementation of a WMS along with automated data collection will likely 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 times. Expectations of inventory reduction and increased storage capacity are less likely. While 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 times, and demand variability. It 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 processes 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, automated 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 similar items and locations into categories. An 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 location, whether it is rack able, max stack height, max quantity per location, hazard classifications, finished goods or raw material, fast versus slow mover, etc. Although some operations will need to set up each item this way, most operations will benefit by creating groups of similar products. For example, if 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 item. You would likely need to maintain detailed information on special items such as boxed sets or CDs in special packaging. You 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 picking. You then set up the quantity 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 etc. You 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 sounds simple, it iswell sort of. In reality most operations have a much more diverse product mix and will require much more system setup. And setting up the physical characteristics of the product and locations is only part of the picture. You have set up enough so that the system knows where a product can fit and how many will fit in that location. You 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” movement). You do this by assigning 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 Sequence. This is the simplest logic; you simply define a flow through your warehouse and assign a sequence number to each location. In 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 Logic. By breaking down your storage locations into zones you can direct picking, put away, or replenishment to or from specific areas of your warehouse. Since 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 Location. Logic uses predetermined fixed locations per item in picking, put away, and replenishment. Fixed 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 Location. Since computers cannot be truly random (nor would you want them to be) the term random location is a little misleading. Random locations generally refer to areas where products are not stored in designated fixed locations. Like zone logic, you will need some additional logic to determine exact locations. First-in-first-out (FIFO). Directs picking from the oldest inventory first. Last-in-first-out (LIFO). Opposite 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 their domestic customers. Pick-to-clear. Logic directs picking to the locations with the smallest quantities on hand. This logic is great for space utilization. Reserved Locations. This is used when you want to predetermine specific locations to put away to or pick from. An application for reserved locations would 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. Maximize Cube. Cube logic is found in most WMS systems however it is seldom used. Cube logic basically uses unit dimensions to calculate cube (cubic inches per unit) and then compares this to the cube capacity of the location to determine how much will fit. Now 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 work. Since this rarely happens in the real world, cube logic tends to be impractical. Consolidate. Looks to see if there is already a location with the same product stored in it with available capacity. May also create additional moves to consolidate like product stored in multiple locations. Lot Sequence. Used for picking or replenishment, 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 location. For example you may chose to use pick-to-clear logic within first-in-first-out logic when there are multiple locations with the same receipt date. You also may change the logic based upon current workload. During busy periods you may chose logic that optimizes productivity while during slower periods you switch to logic that optimizes space utilization. Other Functionality/ConsiderationsWave Picking/Batch Picking/Zone Picking. Support for various picking methods varies from one system to another. In 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 Interleaving. Task interleaving describes functionality that mixes dissimilar tasks such as picking and put away to obtain maximum productivity. Used 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 pick. In large warehouses this can greatly reduce travel time, not only increasing 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 Equipment. 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 process. Since these types of automation are very expensive and are usually a core component of your warehouse, you may find that the equipment will drive the selection of the WMS. As with automated data collection, you should be working closely with the equipment manufacturers during the software selection process. Advanced Shipment Notifications (ASN). If your vendors are capable of sending advanced 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 functionality. Yard Management. Yard management describes the function of managing the contents (inventory) of trailers parked outside the warehouse, or the empty trailers themselves. Yard management is generally associated with cross docking operations and may include the management of both inbound and outbound trailers. Labor Tracking/Capacity Planning. Some WMS systems provide functionality related to labor reporting and capacity planning. Anyone that has worked in manufacturing should be familiar with this type of logic. Basically, you set up standard labor hours and machine (usually lift trucks) hours per task and set the available labor and machine hours per shift. The WMS system will use this info to determine capacity and load. Manufacturing has been using capacity planning for decades with mixed results. The need to factor in efficiency and utilization to determine rated capacity is an example of the shortcomings of this process. Not 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 work. I am, however, a big advocate of labor tracking for individual productivity measurement. Most WMS maintain enough data to create productivity reporting. Since 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 systems. Unless the WMS vendor has 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 here. While we are all hoping that integration issues will be magically resolved someday by a standardized interface, we isnt there yet. Ideally youll want an integrator that has already integrated the WMS you chose with the business software you are using. Since 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 beginning 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 management. I dont see this as a unilateral move of WMS from an add-on module to a core system, but rather an optional approach that has applications in specific industries such as 3PLs. Using 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 separately. If 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 these WMS based business systems are a good fit. Implementation TipsOutside of the standard “dont underestimate”, “thoroughly test”, “train, train, train” implementation tips that apply to any business software installation ,its important to emphasize that WMS are very data dependent and restrictive by design. That is, you need to have all of the various data elements in place for the system to function properly. And, when they are in place, you must operate within the set parameters.When implementing a WMS, you are adding an additional layer of technology onto your system. And with each layer of technology there is additional overhead and additional sources of potential problems. Now dont take this as a condemnation of Warehouse Management Systems. Coming from a warehousing background I definitely appreciate the functionality WMS have to offer, and, in many warehouses, this functionality is essential to their ability to serve their customers and remain competitive. Its just important to note that every solution has its downsides and having a good understanding of the potential implications will allow managers to make better decisions related to the levels of technology that best suits their unique environment. 仓库管理系统（ WMS ）仓库管理系统（ WMS ）的演变与许多其他软件解决方案是非常相似的。最初的系统用来控制物料在仓库内的流动和贮存，仓库的作用正在延伸到包括轻型制造业，交通运输管理，订单管理，和完整的会计制度中。利用与先前的业务有关的软件，制造资源计划，作为一个比较，材料需求计划（ MRP ）开始作为一个规划要求，原材料的生产环境的系统。 物料需求计划很快演变成以MRP系统，补充调度和容量规划为基础的逻辑制造资源计划（ MRPII系统）。最终MRPII系统演变成企业资源规划（ ERP ），吸收所有的MRPII系统的功能包括充分的财务与客户和供应商管理功能。现在，无论仓库管理系统演变成一个以仓库为中心的ERP系统是一件好事或不可达的辩论。清楚的是，在仓库管理系统，企业资源规划，布局规划要求，交通运输管理系统，供应链计划，高级计划与排程，以及制造执行系统之间扩大重叠功能性只会增加那些寻找软件解决方案业务的公司混乱水平。 尽管仓库继续获得额外的功能，最初的仓库管理系统的核心功能还没有真正改变。其主要目的是控制管理系统在工艺操作相关联的交易中的流动和材料储存。定向采摘，定向补充，定向收集是仓库的关键。从一个软件供应商到另一个在一个管理系统中详细的安装和处理可以有一个很大的差别，但是其基本逻辑将使用相结合的项目，地点，数量，度量单位，并以收集信息以确定在哪里储存，在哪里挑选，以及以何种顺序执行这些操作。 一 最低限度，一个仓库管理系统应采取下列措施 有一个灵活的定位系统。 利用用户定义的参数，指导仓库任务和使用Live文件来执行这些任务。 有一些内置的一体化和数据收集设备结合体。 您是否真的需要仓库管理系统？ 并非每一个仓库需要一个仓库管理系统。当然，任何仓库可受益于其中一些功能，但这些受益是否足以证明管理系统最初的和正在进行的相关费用是正确的？仓库管理系统是大的，复杂的，数据密集型的应用。他们往往需要大量的初始安装，很多系统资源的运行，很多正在进行的数据管理为继续运行。没错，你需要“管理”你的仓库“管理”制度。一般情况下，大规模的行动最终将建立一个新的IS部门用来唯一负责管理仓库管理系统。 二 声明1) 仓库管理系统将减少库存！2) 仓库管理系统将减少劳动力成本!3) 仓库管理系统将增加存储容量！ 4) 仓库管理系统将提高客户服务！5) 仓库管理系统将增加库存的准确性 ！ 三 现实 实施一个仓库管理系统用来自动的数据收集将可能使你的准确性增加，减少劳动力成本（提供需要维持系统的劳动力少于物品保存在仓库楼需要的劳动力）和更好地来服务客户以降低周期。预期库存减少和增加存储容量的可能性较小。虽然在接收过程中增加了准确性和效率可能降低库存安全水平，但这种降低产生的影响与整体库存水平相比可以忽略不计。控制库存水平批量最主要的因素是多种尺寸，交货时间和需求的变化，仓库管理系统将对任何因素有重大影响是不可能。而且同时仓库管理系统确实的为更多的有组织的存储提供工具，因为这种存储可能会导致更多的存储容量，相对于这种改善您之前的仓库管理系统是多么草率啊。除了劳动效率，决定实施仓库管理系统的决定因素，往往与一些能满足您的客户的需求有更多关联，比如您目前的系统不支持（或不太支持）像先进先出，交叉对接，自动挑选补充，波采摘，多种跟踪，停车场管理，自动数据采集，自动材料处理设备等 。四 设置 仓库管理系统的设置需求是广泛的，每个项目和地点都必须保持在详细或分组类似项目和地点分类。一个例子，项目详细程度的特点将包括确切尺寸和重量，每个项目在每个单位的项目储备（项目，案件，托盘等），以及信息，如是否可以与其他物品混在一个位置，无论是的最高层次，最大堆叠高度，最高量的位置，危险性分类，半成品或原材料，快与慢动，等。尽管一些行动将需要用这种方式设立每个项目，但大多数业务将有利于创造群体的类似产品。例如，如果你是一个音乐CD分销商，您将创建集团单一CD和双张CD ，保持详细的尺寸和重量的资料在组一级，只需要对每个项目附上组代码。您可能会需要对特殊物品保持详细的资料，如盒装套或CD的特别包装。您也可以为地域的不同类型在您的仓库里创造群组。一个例子是，为您用于CD采摘的三种不同大小前瞻性采摘地点建立3个不同群体（小一，二，三）。然后，您可以建立单一的光盘数量，将适合P1，P2和P3的位置，多种双张CD适合在小一，二，小三的位置等。您可能还设立案件的数量，每个CD组光盘数量,货箱的数量和光盘的每个后备存储位置组。如果这听起来很简单，但在现实中很多业务有更多元化的产品组合，将需要更多的系统设置。而且建立产品的物理特性和产品的位置只是蓝图的部分。你设定的使系统知道产品可以适合哪里并且多少产品将满足这个地方已经足够了。您现在需要建立必要的信息，以让系统决定从哪些位置选择，补充，并采集，并在这些事件应该出现这些序列中（记得仓库管理就是“指示”流动）。你分配具体逻辑的的做法使各种组合项目/订单/数量/位置信息将出现。 下面我列出一些用于确定实际位置和序列的逻辑1) 位置顺序。这是最简单的逻辑;您只需确定流经你的仓库和为每一个地点分配序列编号。 为了挑选这是把您选择的在流经的仓库排序，在采集逻辑将寻求在第一位置的顺序适合的产品。 2) 区逻辑 。由于把你的储存地点分到区，您可以直接采摘，收集，或补充或特定地区的仓库。自区逻辑唯一指定的一个地区，则需要再加上一些其他类型的逻辑，以确定确切位置在禁区内。 3) 固定的位置。 逻辑使用预先确定的固定地点，每一项目中分拣，采集 ，和补充。固定地点是一块采摘挑选和个案选择的行动最常用的首要位置，但是，它们也可用于二级存储。4) 随机地点。由于电脑不能真正随机（也不想要他们）的任期随机位置有点误导。 随机地点一般指的是产品不会储存在指定的固定地点的地方。如Zone逻辑，您将需要一些额外的逻辑，以确定确切位置。5) 先入先出（ FIFO的）。首先指示挑选最古老的库存。6) 最后，先出（ LIFO ）。我不认为这种逻辑有任何实际应用，直到我的网站访问者发送一封电子邮件，说明自己在国内和海外销售易腐货物的行动。他们为海外客户使用LIFO（因为长期在途中）和为国内客户使用FIFO。7) 挑选到清楚。用最少的人手挑选逻辑指示的地点。这种逻辑是巨大的空间利用率。8) 预留位置。这个是在预约具体地点采集时使用。从申请预留位置将交叉对接，在那里你可以指定一定数量的入境货物转移到具体的举办地点外，或直接到等待出境拖车。9) 最大限度地立方。立方体逻辑中是在WMS系统发现最多的，尽管它很少使用。立方体逻辑基本上使用单位面积计算立方体（立方英寸每单位）。然后比较这个位置的立方体能力，以确定有多少适合。现在，如果这些单位能堆叠成的位置，以填补每立方英寸的空间中的位置，立方体逻辑将工作。由于这很少发生在现实世界，立方体的逻辑往往是不切实际的。10) 巩固。查询看是否有一个以现有性质存放相同产品的位置。还可以创造更多的行动，以巩固同类产品存放在多个位置。11) 很多序列。用于采摘或补充，这将使用大量批号或日期，以确定位置，以选择或补充。这是非常常见的逻辑结合多种方法，以确定最佳的位置。例如您可以选择使用挑选到清晰的逻辑内先入先出逻辑当有多个地点以同样的收据的日期。您也可能会根据目前的工作量改变的逻辑。在繁忙时段内您可以选择的逻辑，优化生产力，同时在速度较慢时期您切换到逻辑，优化空间利用率。 五 其他功能/思考 1) 波拾取/批次拣货/区拣货。支持各种不同选择方法从一个系统到另一个。 在高销量的完成作业，可采摘逻辑中的一个关键因素韦氏选择。见我的文章的订单欲知有关这些方法。 2) 任务交织 。工作交织介绍混合不同的功能，任务，如挑选和采集获得最大的生产力。主要用于全货负荷运作，任务交织将指示叉车经营者
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