Warehouse Management Systems Effectively Applying Technology to Processes Thomas K. Cassidy Abstract As organizations become more customer-oriented and interested in protecting the bottom line, the order to cash, or customer fulfillment cycle becomes a natural focus of attention. The application of technology is often a key strategy in this battle and a Warehouse Management System (WMS) can play an integral role in controlling operations, automating manual processes and putting the pressure on processes and functions further upstream in the Supply Chain. A successful WMS implementation focused on process improvement and inventory control can transform the warehouse from a black hole of information and inventory into a controlled profit builder and service provider. Armed with the ability to improve and streamline operations from reorder points to bills of materials and manifests, efficient warehouses improve space utilization, increase inventory turns and cut order lead-times. Combining this with process improvements enhances overall operations and reduces the cost to run the warehouse. The end result can take the pressure off the warehouse operation and redirect attention toward improving marketing forecasts, purchasing and manufacturing schedules and logistics services. This paper will discuss how several of the key processes of operating a warehouse are integrated in the functionality of a WMS. Applications and references are based on the WMS*Yantra package. It is intended to point out the impact of WMS implementation on warehouse processes from the physical movement of inventory to the planning functions that support the flow of goods, services and information through the Supply Chain. Please note that it is not possible to detail all of the functional process applications of a complex WMS or Supply Chain Execution System (ex. Task management, resource management and reverse logistics) within these proceeding guidelines Keywords Warehouse Management System (WMS), Supply Chain Execution, Inventory Management, Storage, Value Added Services (VAS), Inbound, Outbound, Pick & Pack, Postponement, Compliance. Strategy The Enterprise Resource Planning (ERP) boom of the nineties has not only led to a tightening of the belt in many organizations, it has also followed a course through the functional silos and departments within companies. Traditionally, the supply chain and the warehouse in particular have been an afterthought in this process. Warehouse
Management Systems have not typically been considered an integral part of ERP implementations. This standard is changing. As systems integration provides detailed and historical cost controls, the areas outside of, or disconnected from this realm are falling under the microscope. A good example of the need for integration is the introduction of a new product to the market. If the product is a hit and the consumers can't purchase it due to lack of availability in retail outlets, the introduction is a failure. At this point we are naturally inclined to place blame. The marketing and purchasing group will be pointing the finger at the distribution channels for failing to have the product to market, while the distribution team will be returning fire claiming the manufacturing or purchasing schedule failed to meet demand and lead times. Multitudes of factors drive the need for change. The two most common are no stranger to most companies "cost" and "speed", or the need to get it there faster and cheaper. Complementing this strategy is the advent of new technology. The warehouse operation can take advantage of advances in the transfer, management and control of information from both internal and external sources. Internal operations are taking advantage of advances in Radio Frequency (RF) technology to speed the flow of information and materials. Value Added Services The effective use of value added services (VAS) is recognized as a potential means to improved transit time and reduced inventory. The planning and execution of VAS can mean success or failure to the supply chain. Essentially value-added services are used to differentiate a unit of product from the standard stock keeping unit (SKU) stored in a warehouse or distribution center.
Specific retailers or customers of the distribution network may require unique features of the product. This could range from affixing barcodes, price tags or promotions stickers to product packaging, inserts, kitting or light assembly. Once complete, these changes to the unit limit the customer orders for which individual product can be allocated. Successfully managing the point of VAS can have dramatic impact on product handling, storage and carrying levels. Compliance Hand in hand with VAS are compliance issues. In an effort to simplify and standardize the receipt of product, many customers are demanding that their vendors meet specific compliance standards. This can pose significant hurdles for the distribution team and can often make the difference in gaining and retaining important customers. Compliance issues can range from providing EDI transactions to the format of the label on each carton or pallet. Inbound In its simplest form the inbound process has two key processes, planning and execution. Each possesses critical components that set the stage for the flow processing of material and goods through the warehouse. Inbound Planning Ideally, the warehouse will be receiving via Advanced Shipment Notifications (ASN) or Purchase Orders (PO) electronically from manufacturing sites, freight forwarder, suppliers, etc. The ASN permits the inbound planner to schedule deliveries, dock doors and receipt operations. If these are not being generated from outside sources, it will be to the operator's advantage to create them manually prior to arrival. Manually receiving
merchandise without ASN's or PO's is a cumbersome task that will delay the flow of goods. Inbound Execution Inbound Execution is comprised of three main areas; start receipt, receipt and putaway. The start receipt function will verify and ASN exists and open the ASN. If it does not exist, the ability to manually create an ASN will be activated, or if there is insufficient information to create an ASN, a 'dummy' ASN can be created. Each of these options will pose and ascending layer of interaction and delay. At this point as well, any items or quantities required for special handling (ex. Quality Control checks, notification of rework required, etc.) will be flagged in the system for diversion or hold. Once receipt has been started License Plate Numbers (LPN's) can be created and placed on each unit. The LPN will then become the primary data point to follow the unit through the warehouse. Many company's compliance manuals will require LPN information be affixed to each package prior to receipt. This significantly increases receipt throughput. In a warehouse receiving via Radio Frequency (RF), cases or SKU's can be automatically received with a simple scan. In non-rf scenarios receipt can be done unit by unit or worksheets can be printed for manual receipt on the CRT. Once all discrepancies are resolved, receipt can be closed, the host computer updated with new inventory and putaway moves will be generated. Putaway/Product Diversion The first step in the putaway process will be to check pending orders and look for opportunities to bypass putaway completely, moving inventory directly to shipping. If this is not feasible the putaway sequence will begin. If the system is designed to
automatically generate putaway movements it will query the extensive table of putaway rules to respond determine the putaway location and create putaway tasks for the user. In a RF warehouse, users will merely scan the unit, case or pallet LPN (depending on setup) and will be directed to the putaway location. Putaway rules can be based on a number of criteria supporting dedicated to random location selection. Changes or discrepancies in putaway can be made on the spot, updating the database immediately, eliminating manual processes and maintaining inventory accuracy. Non-RF putaway is done manually from pre-printed sheets. Once complete, moves are verified in the system and discrepancies rectified manually. When inventory locations are not generated by the system, RF capabilities are set to scan the unit LPN and respective putaway location determined by the user. Manual scenarios are similar to above with the exception of the pre-printed task sheets. Actual moves are recorded manually then updated in the system Storage & Inventory Management The counting of inventory and maintaining inventory accuracy are key focuses of storage and inventory management. The two types of counts are physical and cycle counts. The physical count process involves a complete count of the entire inventory in the warehouse. This is typically done once or twice a year and must be performed during non-operating hours or a shutdown period while inventory is static.
Physical Counts Although a physical inventory will provide the most accurate and current inventory information, the labor involved and the need to be performed during non-operational hours is often limiting. For the WMS this is generally an offline procedure which involves the manual updating of databases after inventory count completion and prior to operations startup. Cycle Counts The cycle count process takes an incremental approach to counting and inventory maintenance. Individual SKU's or storage locations will be scheduled for count verification on a predetermined basis. In the RF warehouse inventory cycle counts can be verified on-line and discrepancies adjusted immediately. Available inventory levels will be maintained accurately while inventory discrepancies can be isolated in an accounting bin for rectification. A common advantage of cycle counts is that physical inventory levels can be maintained accurately with little to no impact on the operation (i.e. no shutdowns). Counting can often be completed more frequently than physical counts, as often as quarterly versus annually. As well, a flexible WMS will allow the ability to customize counting frequency by SKU, product type, location, etc., and schedule counting to occur during other work activity. Inventory Management The inventory management function serves several process management purposes; inventory adjustments, tracking and inquiries, DC to DC inventory transfer, space utilization and inventory movement control.
Inventory Audit Logs allow the look up and auditing of inventory changes. Users can select specific audit details for inquiry by specifying criteria. Each audit record can be exploded to view the sales order, purchase order, or container relative to the audit on a separate screen. The information is sorted in descending order of time. A work-back from the last record can be adopted to match stock pictures. The Inventory Adjustment process allows for the stock adjustments for an SKU. Controls for stock adjustments can be user or location specific for security purposes. This provides a controlled process for inventory adjustments within the warehouse. The Inventory Inquiry process allows users to view SKU's or LPN's at the warehouse level and location level. As well, users can drill down if further information is required. For example, inventory inquiries can be based on SKU, model, product type, individual cases or pallets, product class, quality status, lot number, FIFO, country of origin, allocatable/non-allocatable and pending pick/ship status. The ability to control movements can be critical for a number of key processes. User may wish to inquire the details of movements, modify any movements not yet completed (or modify and complete at once), cancel incomplete movements, complete a movement, group a series of movement in a batch or release a batch of movements into individual moves. The DC to DC Transfer process allows users to create a transfer order to move inventory to another warehouse or distribution center (DC). The system will manage the transfer using typical rules for order processing it will however bypass customer specific processes such as wave planning and generate shipment information automatically. The Perform Movements process provides a variety of options for performing move tasks based on work type. Work types can be flagged to signal product movements into "locations". Generally, the following operations will occur; Create Move Task, Perform Move Task, Report Complete Move Tasks and Manual Move.
The process of consolidation or space utilization can help identify locations with the same SKU and create move tasks to combine and consolidate. This is often a background job that can be run automatically. The objective is to maximize the number of empty locations - not to minimize the number of locations used. Outbound Like the inbound function, outbound operations consist of planning and execution. Each possesses critical components that complete the inventory transactions, update systems and take the merchandise from the warehouse system to the transportation system. In its simplest form, the outbound modules process downloaded orders, create loads and shippers for orders, create and release optional pick waves, run pick, pack and ship activity and generate all necessary documentation and paperwork. The shipper will be the command file (RF warehouse) or printed file (manual warehouse) which will govern the picking, packing and shipping of an order or group of orders. Outbound Planning The planning of the outbound cycle is more complicated than the actual execution phase. The initial process of creating loads and shippers starts with the consolidation of orders downloaded from the host. As mentioned before, shippers are automatically created and inventory allocated for transfer orders. All other orders will run through a consolidation process. By matching orders to consolidation rules, the system can look for opportunities to consolidate orders and improve pick, pack and ship efficiency. As well, inventory checks can be run to ensure orders dropped will be meet fill rate standards. Once order consolidation is complete, shipment mode selection occurs. In the case of Truckload (TL) movements, a load planning module can be incorporated for trailer utilization. Otherwise orders will run through a carrier selection module. Here a rules-based
selection of carriers is made based on order/shipment characteristics, customer preference, etc. Once the carrier is selected, a decision point determines if the order is ready to task and generate a shipper. If not, the shipper is rerouted through the load planning module for refinement. Otherwise, shippers are compared versus the inventory and units are allocated against the shipper and routed for wave creation. Wave creation will logically group shippers for release to picking and can be automatic or manual. Automatic waves can be created at preset times. They are rules-based waves that may not be released for picking after creation. In the manual wave creation scenario, a rules-based option is available. Here users release shippers for wave consideration on a WMS terminal. The same rules will apply as in previous situations. This is generally the case with exception shippers such as emergency or special orders. In a case where the rules-based option does not meet the specific needs of a special order(s), manual wave creation can occur. In this situation, shippers are manually assigned to a wave based on user preference. Once all necessary shippers are assigned to waves, the wave is released. Wave release can be a complicated process. Once released the wave must first be tasked. This means that each of the unique specifications or operations of the wave are identified. Product collation is identified, pick locations are determined, and special cartonization requirements (box, number of units, orientation, etc.) are noted. >From this information a pick strategy is generated and physical tasks assigned. At this point work tasks, pick strategies and print jobs are batched for efficiency and routed to the respective locations pending picking.
Outbound Execution Once released, waves pass through a series decision points. First, if the operation involves pick-to-light or an automated sortation. Information is automatically downloaded to the respective systems. In some cases, these systems will control the physical pick task activity as well as the movement of cartons to shipping. Pick & Pack In the case of RF Pick, if the system is not configured to direct the start pick location, the user will do so. This will be a user-initiated pick and sort operation. If the system is configured to indicate the start location, users can choose to pick multiple orders and sort while pick or pick individual orders, pick and sort. The packing area setup can also play a role in this decision based on the ability to consolidate order picking and sort at pack. After waves are picked, they are confirmed. This occurs automatically in a RF-Pick operation since units are confirmed as they are picked. Printed pick sheets can also be scanned by RF (along with units for accuracy if desired) or keyed after picking to verify picking and completion. At this point waves are verified versus orders to ensure fill completion. If shortages are found, wave/shipper information is run through a shortage process to verify if it can be completed or should be held. Once inventory can be allocated to the order it is reprocessed and moved to shipping. If inventory is not available to complete the shipper, the decisions is made whether to unpick the shipper and make the inventory available for pending orders or to hold the order for inventory arrival.
Shipping Once completed shippers have been verified, carton-by-carton against inventory and orders, they can be forwarded to shipping. In an automated conveyor diverter system, they will proceed directly to the shipping lane. Otherwise, they will be manually moved to the shipping area. Once in the shipping area, system generated RF commands or printed reports can detail the ship mode and instructions required. Pallets can be built with specific cartons. Palletization functionality can be critical in international shipping modes based on customs declaration requirements. Upon carrier pickup for truckload (TL) and less than truckload (LTL) movements, a Bill of Lading (BOL) or Master Bill of Lading (MBOL) can be easily generated. Report format can be customized to meet carrier and/or government requirements. Parcel shipments can often move directly to the outbound door(s). Carrier specific labels are part of the WMS functionality and can be incorporated into pick sheets generated at packing and affixed to the carton. Once weighed (in many cases the system can generate carton weight accurately) the carton can be scanned at the shipping dock to confirm shipment. Carrier rate charts can also be built into the system. At pick up time a parcel manifest will be generated automatically. As with all of the other modules of the WMS, once orders are complete and shipped all databases are updated on the host system. This will include (but is not limited to) removal of all shipped inventory form the system and generation of Advanced Shipment Notifications ASN's (if required) to customers. Postponement Strategy There is a one step in the shipping process that is getting a lot of attention. Prior to shipping the ship date must be verified. A pack and hold order/shipper will be processed
up to the actual ship point and then held until ship date. This can be a critical piece of a successful postponement strategy. Warehouses operations interested in shortening the customer fulfillment cycle may incorporate a postponement strategy to expedite shipping and delivery for specific items or to specific customers. This strategy takes careful planning and execution. Postponement involves the advanced generation of shipments. This can be initiated by a customer that places advanced orders with future ship dates or by a provider that projects orders and fulfills in advance against the projection. The warehouse can see added benefits in productivity by filling future orders in low production periods. If future orders involve customer specific compliance requirements postponement can be viewed as a value added service (to be discussed). Although postponement can speed the fulfillment process form order to delivery, if not managed well, it can negatively impact the inventory goals of the warehouse. Careful planning ensures that inventory levels are being kept at optimal levels and future orders are not robbing the warehouse of valuable space. Value Added Services Value Added Services (VAS) are often key decision criteria in WMS selection. The ability to meet specific customer needs is ever increasing as a need in a flexible WMS. As well, a VAS strategy is often the critical piece of an inventory management strategy focused on minimizing inventory levels and meeting time in transit requirements. As mentioned before a sample of services are affixing barcodes, price tags or promotions stickers to product packaging, inserts, kitting or light assembly.
Value added services consist of three main processes; configuration, planning and execution. Configuration Configuration defines the unique characteristics of the services. VAS can impact reporting on Bills of Materials or special printed reports. They can specify physical processes and instruction as well as redefinition of product class, kitting rules and pack methods. Or, they can detail rules for the processes such as batch, outbound and wave rules. VAS Planning In planning value added services, work orders must be created or imported. External work orders can often be downloaded into the system based on order specific or dynamic requirements. Manual work orders can also be created on an as needed basis for specific tasks. Once work orders are received, the inventory is verified. The item or SKU is compared to the minimum specified quantity. If sufficient quantities exist for specified needs, orders are created and routed appropriately based on kitting or packaging requirements. VAS Execution The release of work orders to the warehouse will result in specified inventory movements for affected units. RF or paper depending on the warehouse will be used to execute these tasks. Once move tasks are complete, value added services are performed.
When VAS is complete the work order and respective unit(s) of inventory are either released as work in process toward an order or shipment or released back into active inventory as a new product or product class for pending and future orders. Once released from VAS, all necessary inventory updates will be made. Conclusion On the surface, warehouse processes may seem trivial and perhaps mundane. It is in the methodology of replicating these processes in a computer model, with the intent of added efficiency and improved flow, that one can see how complicated the warehouse operation truly is. In today's business world to operate a smooth running warehouse is not enough. The perception of a precision operation could be masking symptoms that are undermining the organization's progress. The processing of orders is not enough. Orders must be processed in the right place, at the right time and with the right product. As new products hit the market and the customer order frenzy ensues, it is the warehouse's ability to receive and process information that can make or break the value perception in the customer's eyes. As well, armed with data, the WMS can interact with the ERP while the operators work hand in hand with marketing and purchasing. to track and meet demand, minimize inventories and overhead, ultimately strengthening the bottom line. Thomas K. Cassidy Director - Supply Spiral Solutions Alliance Consulting 2005 Market Street, Suite 3200 Philadelphia, PA 19103 Phone: (800) 706-3339 ext.1115 (610) 909-6813 tcassidy@alliance-consulting.com
Biographical Sketch Thomas K. Cassidy Tom is a Director of Solutions Architecture in the Supply Spiral Solutions Practice at Alliance Consulting. He is a recognized member of the engineering community with experience in technology applications, distribution/fulfillment operations, planning/support and consulting. He has successfully managed Industrial Engineering, consulting and operations teams on projects involving Technology Integration, Facilities Planning, Total Quality Management, Business Process Re-Engineering, Core Process Redesign, Site Location, Warehousing and Transportation Operations. Prior to Alliance, Tom held Manager positions at both United Parcel Service and answerthink. Tom has a Master of Engineering in Engineering Science from Penn State University and a Bachelor of Science in Industrial Engineering from Lehigh University. He is member of the Council of Logistics Management, the Engineers' Club of Philadelphia, a Senior Member of the Institute of Industrial Engineers (IIE), The IIE Society for Engineering & Management Systems, Director of IIE's Division of Logistics, Transportation & Distribution a former Chapter President and the current Region 2 Vice President.