Patent Publication Number: US-2003233264-A1

Title: Manufacturing order scheduling and materials replenishment system

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to manufacturing order scheduling and more particularly to de-coupling planning and execution phases within a manufacturing order scheduling and materials replenishment system.  
       [0003] 2. Description of the Related Art  
       [0004] Scheduling work in a manufacturing environment is a complex process. Most factories use an automated planning and scheduling system to ensure that customer demand is satisfied in a timely manner with minimum inventory. To achieve this goal, such planning requires that work for each manufacturing line is efficiently scheduled, that the appropriate materials needed to complete each task performed are available when needed on the manufacturing line, and that products are manufactured in the order that the products are needed. To produce a manufacturing schedule, customer orders should be received and analyzed, priorities should be assigned to items to be manufactured, manufacturing resources should be allocated, work should be scheduled, raw materials and/or parts should be obtained and delivered to the manufacturing line, work in progress should be tracked, and variability in availability of raw materials and/or parts must be handled. Many manufacturing facilities plan and manage these many tasks by combining multiple computerized planning and scheduling systems with paper-based management systems.  
       [0005] An example of a widely-used commercially available automated planning and scheduling system is i2 Technologies, Inc.&#39;s Factory Planner and Rhythm Collaboration Planner. The i2 Factory Planner generates work schedules and material requirements schedules using customer-provided inputs of demand and inventory. The i2 Rhythm Collaboration Planner helps organizations to quote and promise order delivery to customers in real-time while obeying customer constraints on lot sizes, number of shipments, and time between shipments. The i2 Rhythm Collaboration Planner helps provide a global view of the entire supply chain from sourcing to delivery. These products handle the complicated scheduling for large, distributed, complex manufacturing environments. However, any automated planning and scheduling system can only produce accurate results if inputs to the system are accurate.  
       [0006] Most businesses schedule manufacturing activities based upon forecasts of demand for products. Work is typically scheduled on a daily or weekly basis to meet demand predicted based on past sales. Inputs to the automated planning and scheduling system are demand forecasts.  
       [0007] To ensure that demand is satisfied, most factories maintain inventories of both parts and/or raw materials. Each type of inventory typically includes stock to accommodate the average usage rate and stock to meet variations in demand.  
       [0008] However, maintaining high inventory levels does not necessarily guarantee that the right inventory is available when and where it is needed. A material delivery schedule is needed that delivers material to the manufacturing line prior to the time the material is needed during manufacturing.  
       [0009] Furthermore, due to limited space in most factories and the expense of maintaining warehouses of inventory, it is desirable to maintain only the minimum inventory necessary to meet demand. Some factories operate on a build-to-customer-order model where no product is manufactured unless it has been ordered by a customer. This model enables the factory to operate with minimal inventory of finished products, but does not address the inventories of materials.  
       [0010] In addition to minimizing material inventory, it is also desirable to minimize material handling to ensure that materials are delivered to the right location at the right time.  
       [0011] Problems with scheduling manufacturing activities are exacerbated in a mass production manufacturing environment for commodities that are built to customer orders. The term commodity describes a mass-produced unspecialized product. In such an environment, the timeframes for manufacturing and delivery activities may be sub-hourly. Demand forecasts do not reliably predict material needs at this level, and schedules based upon demand forecasts become less and less accurate as time elapses between the time the work is scheduled and the time the work is initiated on the manufacturing line. Nor do demand forecasts respond to variations in material needs resulting from a typical customer orders. Scheduling based upon demand forecasts does not provide the responsiveness to changes in inventory and work schedules needed to ensure that materials are delivered to the right place at the right time.  
       [0012] A further problem in scheduling work and material deliveries for performing the work is that a current state of the available inventory, updated sufficiently often to keep up with consumption of material, is very difficult to obtain. Materials can reside in many locations, or material sources, within the factory. For example, the material may reside as part of work in progress at an operation on a manufacturing line, the material may reside in a stockroom, or the material may be in transit from one material source to another. The material may also be available from a supplier that is close enough so that the material could be used on the manufacturing line a few hours later.  
       [0013] It is known for a new plan generated from demand and supply data to consider previously requested materials (e.g., Purchase Orders or similarly generated requests) and consider previously unrequested availability to be available at fixed lead times (e.g., at X business days or Y hours in the future). A current planned request typically relied on an assumption of the static nature of all previous demand and supply inputs that were provided to the current plan generation.  
       [0014] More specifically, any material movements that had already been requested were included in a plan. To balance the need to request materials early enough to keep the factory moving while minimizing on-hand inventory, frequent, accurate material request were sent to suppliers. If requests were sent too frequently, however, the schedule from a given planning cycle would fail to reflect some material movement requests that would be initiated after the start of the planning cycle and be already under way when the planning cycle completed. The result would be that orders were not scheduled for which materials were available and new material requests generated from the planning cycle might duplicate some of the requests sent during the cycle based on older plans. One way of minimizing this inaccuracy was to limit the frequency of material requests sent to suppliers to when not in a planning cycle.  
       [0015] Additionally, it is known to use fixed lead times to calculate the time that is used for materials to be processed and transported between the suppliers and the factory. The result of using fixed lead times is that the planning system assumed that materials could be requested at any time and would arrive at exactly the fixed amount of time after the material was requested. In reality, the suppliers needed to receive bunched material requests so that the suppliers could load many different materials on a single truck and transport the loaded materials to the factory on a fairly static delivery schedule. Furthermore, non-working weekends and holidays presented challenges in determining the fixed lead time.  
       [0016] Additionally, it is known to overlay material requests generated from previous planning cycles that had not yet been sent to the suppliers with new requests based on the latest planning cycle.  
       SUMMARY OF THE INVENTION  
       [0017] Accordingly, in one aspect the invention relates to a planning system which incorporates planned initiation of materials request for deliveries at an expected arrival time into the planning cycle. Such a planning system advantageously allows increasing the frequency of material requests (thus minimizing on-hand inventory) and taking advantage of the material requests to schedule demand as early as possible while at the same time improving the accuracy of new material requests. Additionally, in anther aspect the invention relates to a planning system which incorporates availability of materials from internal and external sources during a planning cycle at a dynamically calculated lead dime based upon a variety of variables. Additionally, in another aspect, the invention relates to a planning system which recalculates planned request based upon monitoring of execution transactions occurring while a planning phase time period elapses.  
       [0018] In one embodiment, the inventions relates to a method for scheduling work and delivery of material for items in a factory which includes: obtaining a customer order, determining the current state of available inventory and generating a material request plan for producing the item. The customer order includes an item ordered by a customer and producing the item that requires a required quantity of a required material. The current state of the available inventory of material is determined from a plurality of material sources. A material request plan for producing the item using the customer order and the current state of the available inventory is determined. The current state of the available inventory is performed separately from generating the work schedule and the material delivery schedule. Obtaining the customer order is performed separately from generating the work schedule and the material delivery schedule. The material request plan is performed separately from generating the material request plan.  
       [0019] In another embodiment, the invention relates to a method for scheduling delivery of material for items in a factory which includes: generating a material request plan for producing an item using a customer order and a current state of available inventory and accounting for planned initiation of material requests when generating the material request plan. The material request plan is generated separately from executing the material request plan. The planned initiation of material requests are material requests anticipated to occur during generating of the material request plan.  
       [0020] In another embodiment, the invention relates to a method for scheduling delivery of material for items in a factory which includes: dynamically determining a replenishment lead time, and generating a material request plan for producing an item using a customer order and a current state of available inventory. The material request plan is generated based upon the replenishment lead time.  
       [0021] In another embodiment, the invention relates to a system for scheduling work and delivery of material for items in a factory which includes: means for obtaining a customer order, means for determining a current state of available inventory of material from a plurality of material sources; and means for generating a material request plan for producing the item using the customer order and the current state of the available inventory. The customer order includes an item ordered by a customer and producing the item requiring a required quantity of a required material. The means for determining the current state of the available inventory is performed separately from the means for generating the work schedule and the material delivery schedule. The means for obtaining the customer order is performed separately from the means for generating the work schedule and the material delivery schedule. The material request plan is performed separately from generating the material request plan.  
       [0022] In another embodiment, the present invention relates to a system for scheduling delivery of material for items in a factory which includes: means for generating a material request plan for producing an item using a customer order and a current state of available inventory and means for accounting for planned initiation of material requests when generating the material request plan. The material request plan is generated separately from executing the material request plan. The planned initiation of material requests are material requests anticipated to occur during generating the material request plan.  
       [0023] In another embodiment, the present invention relates to a system for scheduling delivery of material for items in a factory which includes: means for dynamically determining a replenishment lead time, and means for generating a material request plan for producing an item using a customer order and a current state of available inventory. The material request plan is generated based upon the replenishment lead time. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024] The present invention may be better understood, and its numerous objects, features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference number throughout the several figures designates a like or similar element.  
     [0025]FIG. 1 is a flow diagram showing an example of a supply chain for a manufacturer having several factories.  
     [0026]FIG. 2 shows a timeline for scheduling work and delivery of materials for a manufacturing line, receiving deliveries of material from a hub, and initiating work on the manufacturing lines according to the work schedule.  
     [0027]FIG. 3 shows a timeline for a pull through horizon using a resource calendar.  
     [0028]FIG. 4 shows a high level order process which includes a demand fulfillment system of the present invention.  
     [0029]FIG. 5 shows the demand fulfillment system of the FIG. 4 high level order process. 
    
    
     DETAILED DESCRIPTION  
     [0030] The following is intended to provide a detailed description of an example of the invention and should not be taken to be limiting of the invention itself. Rather, any number of variations may fall within the scope of the invention which is defined in the claims following the description.  
     [0031] In the demand fulfillment system and method of the present invention, the inefficiencies resulting from using demand forecasts are overcome by using customer orders and the source for demand, and material availability, and material availability times to determine supply to plan work schedules and material delivery schedules for multiple operations and/or manufacturing lines of a factory.  
     [0032] The demand fulfillment system of the present invention considers all outstanding customer orders as a source of demand from the time the customer order is financially approved until the customer order is fulfilled. Similarly, the demand fulfillment system of the present invention considers all available inventory of material as a source of supply, including material in-house and material available from suppliers that can be delivered in sufficient time to meet production needs. Current supply and demand are updated continuously in an automated data warehouse.  
     [0033] When a required quantity of a material is scheduled to be used at an operation on a manufacturing line, the material is requested from the available inventory allowing sufficient time for delivery prior to the time the material is needed at the operation. When material is in transit from a transferring material source to a destination material source, the quantity of the material in transit is considered to be available as part of available inventory as of the expected arrival time at the destination material source. When the material is accepted at the destination material source, the material is removed from the in-transit inventory and added to the available inventory at the destination material source. Material is considered to be part of available inventory until the material is consumed during manufacturing or otherwise removed from the available inventory.  
     [0034] In the manufacturing environment described herein, a customer places a customer order for one or more products, such as an information handling system. A customer may be an individual or a business entity. The product(s) are built according to the specifications provided by the customer in the customer order and may include one or more components. Generally each component is a commodity that is mass-produced and unspecialized. For example, the customer ordering an information handling system may specify several components such as a processor, monitor, printer, and so on, each of which is mass-produced. The customer order specifies the particular components to be assembled to provide the information handling system product.  
     [0035] For purposes of this application, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an information handling system may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of the information handling system may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communications between the various hardware components.  
     [0036] For simplification purposes, examples used herein may describe a customer order for a single item, wherein an item may represent either a product or a component of a product as described above. The scope of the invention is not so limited, and the invention encompasses the fulfillment of customer orders for multiple products including multiple components. A customer order therefore may include many items and/or multiple quantities of a single item. When a customer order has a single item, as in some examples herein, the assignment of a manufacturing line to fulfill the customer order by manufacturing the item is also an assignment of a manufacturing line to the customer order.  
     [0037] Some items may be manufactured by the manufacturer and other items may be purchased from a supplier but sold as part of a product offered to customers. For instance, the manufacturer of the computer system described above may obtain a monitor from a supplier rather than manufacture the monitor itself.  
     [0038] The term material describes raw materials and/or parts used to manufacture an item. For items which are purchased from a supplier and not manufactured in-house, the term material may be used to describe the item itself.  
     [0039] The demand fulfillment system and method of the present invention generates a work schedule for items to be manufactured and a material delivery schedule for materials to be delivered to manufacture the items.  
     [0040] A work schedule includes a time and location for each item to be manufactured. The location may specify a manufacturing line and/or an operation of at least one operation on a manufacturing line to manufacture the item. A material delivery schedule identifies a material, a quantity, a material need-by time, and a delivery location (an operation and/or manufacturing line) for each material required to fulfill the work schedule. The material delivery schedule is used to ensure that materials needed to manufacture the items are delivered to the location they are needed on the manufacturing line prior to the time when manufacturing the item is to begin. The material delivery schedule is developed on a just-in-time basis so that materials are delivered to the manufacturing line just prior to the time that the material is needed for manufacturing the item.  
     [0041]FIG. 1 shows a supply chain for a manufacturer of items according to one embodiment of the invention. Each supplier  120  such as suppliers  120 A through  120 E supplies parts and/or raw materials, collectively called materials, to the manufacturer. Rather than maintaining a warehouse of materials, the manufacturer obtains materials from at least one external material source. Examples of external material sources include hub  130 A, hub  130 B, and hub  130 C and suppliers  120 A through  120 E. Each hub is in close proximity to one of the manufacturer&#39;s factories, each factory being a factory  140 , such as factories  140 A,  140 B and  140 C. Each factory has at least one manufacturing line such as manufacturing lines  142 A through  142 D. Each manufacturing line may have one or more manufacturing operations (not shown). For factories having multiple manufacturing lines, materials from hubs and suppliers are delivered directly to the operation and/or manufacturing line that needs the material rather than to a general delivery area that serves all operations and/or manufacturing lines for the entire factory.  
     [0042] The term hub describes an intermediate business that agrees with the manufacturer to maintain adequate levels of inventory of materials that can be delivered to the manufacturer&#39;s factory on short notice upon request. The hub makes its own arrangements with suppliers to provide material to a storage location for hub inventory. A hub may be referred to as a Supplier Logistics Center (SLC).  
     [0043] Suppliers may also supply parts and/or raw materials directly to the operation and/or manufacturing line upon request. In the context of the present invention, each external material source such as a hub or a supplier has its own inventory data (not shown). The manufacturer has access to the external material sources&#39; inventory data. The manufacturer manufactures the finished products that have been ordered by customers such as customer  150 .  
     [0044]FIG. 2 shows an example of a timeline of activity on a manufacturing line according to the present invention. In this example, production scheduling activity (i.e., planning) is decoupled (i.e., executed separately) from material replenishment activity such as schedule transmission, materials requesting the build execution activity and the material movement. The production scheduling activity is executed substantially continuously and materials are requested from external material sources. The production scheduling activity accounts for planned initiation of material requests when generating a material request. Planned initiation of material requests are material requests that are anticipated to occurring during the execution of the production scheduling module.  
     [0045] More specifically, at time 0:00, data is loaded into a planning module A10A so that a first production scheduling and planning cycle may be executed (Planning 1). The data that is loaded includes customer orders and available inventory. The planning module A10Adevelops a material request plan that schedules work and deliveries of materials to the factory&#39;s operations and/or manufacturing lines. Available inventory includes external inventory as shown in external inventory data, in this case, the hub&#39;s inventory data. Available inventory also includes in-house inventory of materials that were requested and delivered from an external material source, but that are not currently allocated to a customer order. While one of the goals of the present invention is minimize or eliminate the need for an in-house inventory of materials, excess materials may accumulate when work is rescheduled or when excess parts are delivered by an external material source. This in-house inventory may be stored in a storage room at a manufacturing line or in an excess stock storage room.  
     [0046] The timeline shows three examples of planning blocks that occur during an example time period: planning block  210 A beginning at time 0:00, planning block  210 B beginning at time 1:00, and planning block  210 C beginning at time 2:00. For illustration purposes, planning block  210 A is shown prior to any delivery of material to the manufacturing line. Planning blocks  2101 B and  210 C illustrate scheduling after some material has been delivered by hubs to the manufacturing lines. This material from hubs was requested from the hubs during a preceding planning block. For example, for planning block  210 C, available inventory includes in-house inventory of materials that were requested as a result of the plan developed during the execution of planning module  210 B and delivered during hub delivery block  230 B. Available inventory also includes materials available from external material sources, as shown in external inventory data.  
     [0047] However, because the production scheduling activity is decoupled from the material movement activity, a material request and movement block  220 A may execute before the planning block  210 A complete (e.g., at time 0:15). The material request and movement block  220 A uses information derived from a prior planning block (not shown). In this way, material request and movement are not dependent upon the execution of a particular planning block.  
     [0048] In the example shown in FIG. 2, each planning block allows a set amount of time to generate a schedule (e.g., approximately 1 hour). The set amount of time for the planning block is based upon the length of time that the planning software needs to run. In each planning block, such as planning block  210 A beginning at time 0:00, a schedule is generated for all operations on all manufacturing lines using all outstanding customer orders and all available inventory. A schedule includes a work schedule for work to manufacture items in response to outstanding customer orders and constrained by material availability (i.e., a build execution schedule). A schedule also identifies material requirements and may provide a material requirements schedule for materials to be used to perform the work. The work schedule identifies the items to be manufactured and a start time and location (operation and/or manufacturing line) for manufacturing each item.  
     [0049] The customer order identifies the materials that are needed to manufacture the item. An availability scheme may be used to assign inventory to a particular customer order to be built. It is desirable to use the most readily available material and thus material is provided with an associated availability rating. For example, in one embodiment, unused in-house inventory already at the storage room for the manufacturing line assigned to the customer order receives the highest availability rating to be used in the next work schedule. In-house inventory stored in an excess stock storage room in the factory is given second highest availability rating; hub inventory is given the third highest availability rating; and in-house inventory in a storage room for another manufacturing line is given the lowest availability rating. This availability scheme minimizes in-house moves of materials. Other embodiments may use other methods or other priority schemes to assign materials to customer orders.  
     [0050] A material delivery schedule (i.e., a material replenishment execution schedule) is developed from the work schedule and the manufacturing requirements so that all materials to be used in manufacturing an item are available at the operation and/or manufacturing line at the time needed for manufacturing the item. The material replenishment execution schedule may include staggered delivery of materials to the manufacturing line as items are being manufactured, as long as the material is available at the operation and/or manufacturing line when it is needed (See, e.g., MRE-A, MRE-B, MRE-C and MRE-D).  
     [0051] The present invention allows multiple planning blocks to occur during a single manufacturing shift. The term manufacturing shift describes a typical manufacturing shift of approximately 8 hours during which mass production of items is continuously performed, although the number of hours in a manufacturing shift may vary. The multiple planning blocks produce work schedules and material delivery schedules for a single manufacturing line during each manufacturing shift. Each subsequent planning block overlays a revised work schedule and material delivery schedule over the previously planned work schedule and material delivery schedule. The planning blocks produce a rolling work schedule and material schedule that extends beyond the manufacturing shift. Planning work and material deliveries multiple times during the shift enables the factory to respond to changing material needs of each manufacturing line on a very short-term basis. Consider the example of FIG. 2 with planning blocks executing substantially continuously (i.e., executing as soon as the data required to execute the new planning block is loaded from the previous planning block). The schedule produced is used to initiate a work schedule after the planning block ends and to generate a material delivery schedule for deliveries until a revised material delivery schedule is generated by a subsequent planning block. Accordingly, when a new planning block occurs, the schedule generated overlays all existing material request which were not either already sent or taken into consideration as inputs to the new planning block.  
     [0052] Replenishment time (i.e., lead time) for material is dynamically calculated when planning work schedules. For example, if material that is needed is part of hub inventory, the work schedule allows for the replenishment time to move the material from the hub inventory to the manufacturing line. Work using that material is not scheduled until after the replenishment time has passed. Replenishment time may also be needed for in-house inventory, but it should be shorter than the replenishment time needed for an external material source. Replenishment lead time for materials that are currently at the hub is calculated based on the expected time for the planning block to complete, the time needed by the manufacturer to evaluate and adjust material requirements, the time needed by the hub to consolidate materials, load the truck and transport the material to the factory, the static delivery schedule for that hub to that factory and the time needed to move materials to the location where the materials will be consumed.  
     [0053] By taking account of replenishment time in planning work, the planning system ensures that work is not scheduled to begin until all parts and/or materials needed for manufacturing the item are delivered to the operation and/or manufacturing line. Orders are not scheduled that cannot be completed due to missing parts.  
     [0054] At time 1:00, the plan is provided to the manufacturing line and work included in the work schedule. Each new materials request is based upon the latest saved plan data and thus the material requests and execution block  220 B use the saved plan from planning block  210 A.  
     [0055] The materials delivered prior to the next planning block are available as inventory for work to be subsequently scheduled. For example, materials that arrive prior to the execution of the planning block  210 B are available as part of in-house inventory for planning block  210 B. According to the present invention, material is requested so that the material received in response is available at the manufacturing line just in time for manufacturing the item. Material requests are made to ensure that a delivery of material in response to the material request is destined for a single manufacturing line.  
     [0056] Each planning block such as planning blocks  210 A,  210 B, and  210 C produces another work schedule using all available customer orders and all available inventory. Additionally, build execution cycle blocks  220 A,  220 B, and  220 C and material replenishment execute cycle (MRE) blocks  230 ,  240 ,  250  and  260  use the most recent saved plan to generate materials requests.  
     [0057] In the embodiment of the invention illustrated in FIG. 2, the work schedule is generated independently of previously generated work schedules, although other embodiments may update a previously generated work schedule. Additionally, subsequent planning blocks, when loading new data, add materials that the planning block plans to order during the planning run as planned in-transit materials. Additionally, supplier commitments to earlier request are compared with the original requested quantity. Net differences are used to adjust new requests. Often the work schedule generated at a given time corresponds directly to the work schedule generated in a later planning block, for the work scheduled for the same time period. However, changes in customer orders and available inventory during the time between planning may result in differences between work schedules and thus the new schedule overlays the previous schedule.  
     [0058]FIG. 3 shows a timeline for a pull through horizon using a resource calendar. The pull through horizon indicates on which truck material should be loaded to be at the factory when the material is needed. More specifically, the pull through horizon takes into account non-working hours as well as external lead time and internal lead time when calculating a pull through horizon for what material requirements to fulfill with a next shipment. Non-working hours include time when the factory is closed as well as lunch breaks and other times during which the factory is not operating. The external lead time is the amount of time needed external to the factory to pull materials. The external lead time is calculated as follows:  
     External Lead Time=(Source Lead Time+Manufacturer Evaluation Time)  
     [0059] The Source Lead Time is the time required to physically execute the request and deliver the materials to a designated dock door. The Manufacture Evaluation Time is the duration of the time required to audit planned requests and to perform any required manipulations.  
     [0060] The internal lead time is calculated as follows:  
     Internal Lead Time=(Internal Buffer Time+PTL Replenishment Time)  
     [0061] The Internal Buffer Time is the pull through horizon extension for process variability. The Pick to Light (PTL) Replenishment Time is the time extension to compensate for time required to physically receive materials at the dock and prepare for customer order kitting or boxing. Pick to light refers to a system for identifying for each unit to be built which materials should be pulled from the inventory racks and placed on a hub for use in building a unit.  
     [0062] In the example shown in FIG. 3, the non-working hours are seven hours, the External Lead Time is calculated to be 105 minutes and the Internal Lead Time is calculated to be 60 minutes. Accordingly, the pull through horizon for the 10 PM truck is through 8 AM.  
     [0063]FIG. 4 shows the interaction of the demand fulfillment system  310  with a high level order process. More specifically, the demand fulfillment system  220  is coupled to and interacts with the manufacturing line  142 . The demand fulfillment system  220  also interacts with and is coupled to a hub  130 , which is an example of an external material source. The hub  130  receives material from suppliers  120  and provides material to the manufacturing line  142 . The hub  130  receives information regarding material delivery schedule from the demand fulfillment system  220 . The demand fulfillment system  220  also provides information regarding a work schedule to the manufacturing line  142  and receives information regarding material arrival from the manufacturing line  142 .  
     [0064]FIG. 5 shows the interactions between modules of demand fulfillment system  220 . In one embodiment, the functions of planning module  530  are provided by i2 Factory Planner and the functions of Hub Communication module  540  are provided by i2 Rhythm Collaboration Planner. The invention is not limited to this embodiment, and the functions performed by each of these modules may be performed by modules specially developed for the demand fulfillment system, by a single module, or by other commercially available software.  
     [0065] In some embodiments, the functions of some modules of demand fulfillment system  220  may be provided by commercially available software packages. Other modules may manipulate the inputs and/or outputs as well as provide the necessary interfaces to in-house systems or external systems. For example, inputs are manipulated so that the output of the commercially available software packages is accurately based upon demand derived from customer orders, using materials available from in-house and hub inventory, and with replenishment times taken into account in scheduling work and deliveries of materials. Further manipulation of the output of the commercially available software may be necessary.  
     [0066] WIP Tracking and Control module  320  controls work in progress (WIP) in the various manufacturing lines of the manufacturer, such as manufacturing line  312 . When a customer  150  places a customer order, WIP Tracking and Control module  320  stores the customer order in WIP data  322  which is available to Scheduling module  330 .  
     [0067] Planning module  530  develops a work schedule using the customer order and various other inputs, as will be described below. Ultimately, Planning module  530  provides the work schedule that is used by WIP Tracking and Control module  520  to control the operations performed on the manufacturing lines, such as manufacturing line  322 . Planning module  530  also provides the material requirements that will be needed to perform the work schedule. Delivery Scheduling module  570  uses the material requirements to develop a material delivery schedule for delivery of materials to the operations and/or manufacturing lines.  
     [0068] Planning module  530  also compares the parts and/or raw materials needed to fulfill the customer order with available inventory to determine whether additional materials are needed to manufacture an item of the customer order. Because minimal inventory is maintained at the manufacturing lines, material requests must be issued to move materials to the manufacturing line, both from in-house inventory and from external inventory. Available external inventory and available in-house inventory comprise the available inventory that may be used to fulfill the material request. Planning module  530  may use and/or generate schedule data  532  to determine materials to perform certain work; for example, the material replenishment time may be used as part of identifying available inventory to fulfill the customer order.  
     [0069] Delivery Scheduling module  570  determines when a material request should be generated, typically at the last possible moment that will still meet a request deadline. The materials received in response to in-house material requests and external material requests are expected to be in place when the material is needed for manufacturing the item. Delivery Scheduling module  570  generates an in-house material request to Inventory Manager module  560 , which manages in-house inventory, and/or an external material request such as a hub material request to External Communication module  540 .  
     [0070] When Delivery Scheduling module  570  communicates an in-house material request, Inventory Manager module  560  obtains the available in-house inventory from In-House Inventory data  562 . Inventory Manager module  560  communicates the available in-house inventory to Planning module  530 . Available in-house inventory typically excludes in-house inventory already allocated to another customer order.  
     [0071] External Communication module  540  facilitates communication between the manufacturer and external delivery sources. When Delivery Scheduling module  570  communicates a hub material request, External Communication module  540  determines whether external inventory (here, hub inventory) is sufficient to meet the material request via External Visibility Interface module  550 . External Visibility Interface module  550  provides an interface to external inventory data  552 , which is data maintained by the external material source (the hub or supplier) rather than by the manufacturer. External Communication module  540  obtains a commitment from the external material source (here, the hub) for the amount of material the hub commits to provide to meet the material request.  
     [0072] External Communication module  540  communicates the available external inventory to Planning module  530 . If an external material source cannot fulfill the entire material request, the manufacturer is automatically informed of the shortage via the commitment. The manufacturer can coordinate with the external material source to re-stock external inventory to meet demand and/or use another source.  
     [0073] Netting module  580  communicates net out information to Planning module  530 . The netting module  580  nets out from a next material request as much of the materials that were requested in an earlier materials request based on matching destination and part numbers of the material. Thus the netting module  580  prevents over ordering of material.  
     [0074] Arrival Time module  582  communicates material arrival times to Planning module  530 . The arrival time module  582  allows an arrival time to be factored into planning. The true arrival time is based upon the time that a truck is scheduled to arrive plus the time to get the material to the manufacturing line (i.e., the replenishment time). Accordingly, a late night execution of the planning module knows that material won&#39;t be available until a certain time the next day and will start scheduling orders based upon the true availability of the material.  
     [0075] In one embodiment of the invention, the demand fulfillment system and method also tracks in-transit inventory, also shown in FIG. 5 as in-transit inventory  572 . In-transit inventory is inventory that has been committed by an external material source but not yet received at the manufacturing line. When a commitment from an external material source is received, Delivery Scheduling Module  570  uses the commitment to update in-transit inventory with a planned material receipt, thereby adding the material to in-transit inventory. In this embodiment, in-transit inventory is considered to be part of the available inventory and is used by Planning module  530  for scheduling work. When in-transit inventory is received at the manufacturing line, the material request is “closed” by “zeroing out” the corresponding in-transit inventory and adding the received material to in-house inventory.  
     [0076] Delivery Scheduling module  570  uses the material requirements generated by Planning module  530  and a truck arrival schedule to produce a material delivery schedule. The term truck arrival schedule is used herein to describe scheduled deliveries of available inventory to operations and/or manufacturing lines. A delivery to an operation corresponds to a delivery to an operation material source for the operation. A truck arrival schedule includes in-house deliveries from in-house inventory and/or deliveries of materials from external material sources. The term truck as used herein describes the transport mechanism used to move material from its storage location to the operation and/or manufacturing line.  
     [0077] A truck arrival schedule is used as input for each generation of a material delivery schedule to allow the factory to quickly adapt to changes in material needs and thus to schedule additional or fewer material deliveries.  
     [0078] When materials are received and/or distributed from in-house inventory, this information is entered into Inventory Manager module  560  and in-house inventory data  562  is updated. The arrival of a truck of materials is also entered into Truck Scheduling module  575 , which maintains the truck arrival schedule of trucks scheduled to deliver materials from external inventory and/or in-house inventory.  
     [0079] By using a priority scheme to assign materials to customer orders such as that described above, the demand fulfillment system and method of the present invention are designed to ensure that in-house moves of material are rare and that in-house distribution of materials is performed as efficiently as possible. In addition, material requests are made so that each delivery of material is destined for a single operation and/or manufacturing line.  
     [0080] The term automated data warehouse is used to refer collectively to WIP data  522 , which provides a outstanding customer orders and a current available work-in-progress inventory of materials in work in progress and not in storage; in-house inventory data  562 , which provides a current available in-house inventory of materials for materials that are in stockrooms and at operations but not in work-in-progress, external inventory  552 , which provides a current available external inventory at suppliers and hubs; in-transit inventory  572 , which provides a current available in-transit inventory; and scheduling data  532 , which provides other types of data needed to produce the work schedule and the material delivery schedule. The term current state of the available inventory includes current available work-in-progress inventory; current available in-transit inventory; current available in-house inventory, and current available external inventory. The available inventory included in the automated data warehouse is updated continuously from its respective sources. For example, WIP data  532  is updated by WIP tracking and control module continuously. In the preferred embodiment, data from each of these respective sources is updated no less than every ten minutes.  
     [0081] Other Embodiments  
     [0082] The present invention is well adapted to attain the advantages mentioned as well as others inherent therein. While the present invention has been depicted, described, and is defined by reference to particular embodiments of the invention, such references do not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts. The depicted and described embodiments are examples only, and are not exhaustive of the scope of the invention.  
     [0083] For example, the described embodiment generates a schedule that reflects all outstanding customer orders and all inventory which is then analyzed to produce an work schedule and a material delivery schedule. Other embodiments may use only a subset of outstanding customer orders and available inventory to generate one or more schedules. Such variations are contemplated within the scope of the invention.  
     [0084] The above-described embodiments describe scheduling blocks as occurring at fixed intervals such as two hours. The scope of the invention includes scheduling blocks at other fixed time intervals as well as at variable intervals that are determined during the manufacturing process.  
     [0085] The above-discussed embodiments include software modules that perform certain tasks. The software modules discussed herein may include script, batch, or other executable files. The software modules may be stored on a machine-readable or computer-readable storage medium such as a disk drive. Storage devices used for storing software modules in accordance with an embodiment of the invention may be magnetic floppy disks, hard disks, or optical discs such as CD-ROMs or CD-Rs, for example. A storage device used for storing firmware or hardware modules in accordance with an embodiment of the invention may also include a semiconductor-based memory, which may be permanently, removably or remotely coupled to a microprocessor/memory system. Thus, the modules may be stored within a computer system memory to configure the computer system to perform the functions of the module. Other new and various types of computer-readable storage media may be used to store the modules discussed herein. Additionally, those skilled in the art will recognize that the separation of functionality into modules is for illustrative purposes. Alternative embodiments may merge the functionality of multiple modules into a single module or may impose an alternate decomposition of functionality of modules. For example, a software module for calling sub-modules may be decomposed so that each sub-module performs its function and passes control directly to another sub-module.  
     [0086] Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.