Material requirements planning system

Abstract

An integrated MRP system for distributors, manufacture and job shops is provided. The MRP system of the present invention is specifically directed to an user which manufactures and sells products that have a wide variety of options. In particular, the MRP system of the present invention provides two key features. The first feature allows the user to define items which uniquely characterize the product for a customer order, purchase order, to work order. The second unique feature of the MRP system of the present invention is the application of user-defined formulas which allow the user to include user-defined formulas which determined the quantity and/or size of a part based on the selected options. Thus, the MRP system of the present invention allows the user who manufactures and sells a number of styles with a wide variety of options to employ an MRP system without a correspondingly high manintenance overhead.

Claims

I claim:

1. A computer system for controlling the output of production, including pricing, costing, scheduling etc., of manufactured items, said system comprising:

(a) input means for receiving production information;

(b) data file means for storing said production information in a storage device;

(c) control means for interrogating said data file means, storing said production information and using the result of such interrogation to create a parameter table for controlling said output, said parameter table having a plurality of elements which can be set to pre-determined values or can be determined by user-defined formulas as a function of any of the other elements already in said parameter table;

wherein said control means for interrogating said data file means, storing said production information and using the result of such interrogation to create said parameter table containing said selected production information is selectively operable between said pre-determined values and said user-defined formulas.

2. The apparatus according to claim 1, wherein said production information includes data for sales orders, inventory items, purchase orders, estimates, and work orders.

3. The apparatus according to claim 2, wherein said production information further includes data for product standards including product dependent labor, material, services and other costs items and standard operations including product independent labor, materials services and other costs items.

4. The apparatus according to claim 2, wherein said data file means is divided into separate files, one each for said sales order data, inventory item data, purchase order data, estimate data, and work order data.

5. A method for controlling the output of production, including pricing, costing, scheduling etc., of manufactured items, said system comprising:

(a) receiving production information;

(b) storing said production information in a storage device;

(c) interrogating said storage device, storing said production information and using the result of such interrogation to create a parameter table for controlling said output, said parameter table having a plurality of elements which can be set to pre-determined values or can be determined by user-defined formulas as a function of any of the other elements already in said parameter table;

wherein step (c) is selectively operable between said pre-determined values and said user-defined formulas.

6. The method according to claim 5, wherein said production information includes data for sales orders, inventory items, purchase orders, estimates, and work orders.

7. The method according to claim 6, wherein said production information further includes data for product standards including product dependent labor, material, services and other costs items and standard operations including product independent labor, materials, services and other costs items.

8. The method according to claim 6, wherein said production information is divided into separate files, one each for said sales order data, inventory item data, purchase order data, estimate data, and work order data.

Description

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates generally to a computerized manufacturing system and, in particular, to a new and novel method for controlling the production, including pricing, costing, scheduling etc., by such a system.

(2) Description of the Prior Art

Material Requirements Planning (MRP) is the technique for determining the net time phased requirement of dependent items parts or sub-assemblies from known (e.g. sales orders) or assumed (e.g. sales forecast) independent demand. A Bill of Materials (BOM) is used to define a relationship between the independent demand items at one level and the dependent demand items at the next lower level. In addition, the BOM also is used as the basis for costing and pulling materials from inventory for released work orders. Typically MRP planning is carried out by a general purpose computer operating under software control.

In most prior art MRP systems, there is an "one-for-one" relationship between an independent demand item produced and the BOM which defines the dependent items and the quantity of each dependent item required to build the independent demand item. Some MRP systems have the additional capability of including limited conditions in the BOM. However, such MRP systems do not include any general provision for providing a "many-to-one" relationship between the independent demand items and the BOM.

Unfortunately such MRP systems pose a problem for an user which manufactures and sells products that are available in a wide variety of options. Upholstered furniture companies, for example, sell chairs by style number. They are often available in a variety of fabrics and finishes. Another example is found in the apparel industry where it is common to specify product by style, size and color.

The general MRP solution for this type of manufacturer is to enter into its MRP system a product number and a BOM for each possible style/option combination. While this approach is conceivable, it would necessitate thousands of unnecessary product numbers and BOMs. This would create a huge problem in maintaining the BOMs and entering the data into the MRP system. As a result, there now are a number of industry specific MRP systems which allow, for example, a furniture manufacturer to enter individual styles, fabrics and finishes which correspond to specific sub-BOMs, thereby substantially reducing the total number of BOMs required to be maintained and entered into the MRP system.

Certain disadvantages become apparent for such a MRP system. First, these MRP systems are specific solutions rather than general purpose. Thus, they can not be readily adapted for different industries or even different manufacturers in the same industry. Furthermore, a manufacturer can not add or easily modify his product structure. For example, adding the option of a sectional sofa for an existing style (i.e. add another "degree of freedom").

There have been some attempts at otherwise simplifying, limiting the data entry into the MRP system, and increasing the reliability of production estimates of the MRP system. For example, the Dye patent (U.S. Pat. No. 4,459,663) discloses a data processing system for automatically and efficiently controlling the manufacture of designated end item products and components which are used to make them. The MRP system is a basic MRP system which, in addition, incorporates an unique feature whereby the system automatically maps all end item stock to the jobs on a priority basis every time a MRP report is produced. As a result, it is not necessary to continually update the MRP system with changes made to the original stock allocation as required in prior art approaches.

The Carlson et al reference (U.S. Pat. No. 4,646,238) discloses a MRP system for controlling the flow of semiconductor products and their components through a production facility. In addition to a conventional MRP system, the Carlson patent also provides a method for by-product planning, co-product planning, and downgrading. However, neither of these references provides a solution to the problem of problem in maintaining the BOMs and entering the data into the MRP system for a distributor or manufacturer which sells products that are available in a wide variety of options.

It has thus become desirable to develop a MRP system which allows, for example, a furniture manufacturer to establish an one-to-one relationship between a style number and its BOM without regard to selected fabrics or finishes and, in addition, allows the manufacture to utilize user-defined formulas which determine the quantity and/or size of an item based on the selected options, thereby eliminating the extra number of BOMs required to be maintained and entered into the MRP system.

SUMMARY OF THE INVENTION

The present invention is directed to an integrated MRP system for distributors, manufactures and job shops. The MRP system of the present invention includes multiple modules including inventory control, sales order processing, purchasing, estimating and standards, work order control, and MRP. These modules may be interfaced to an existing accounting package which includes accounts receivables, accounts payable, general ledger and payroll modules. The MRP system of the present invention is specifically directed to an user which manufactures and sells products that have a wide variety of options. In particular, the MRP system of the present invention provides two key features. The first feature allows the user to define items from which one to six options may be specified to uniquely characterize the product for a customer order, purchase order, or work order. The user is only required to maintain limited information about each combination of item and options.

The second unique feature of the MRP system of the present invention is the application of user-defined formulas similar to those that are used in conventional spreadsheet programs. This is particularly useful in defining the BOM since the MRP system of the present invention allows the user to include user-defined formulas which determine the quantity and/or size of a part based on the selected options. Thus, the MRP system of the present invention allows the user who manufactures sells a number of styles with a wide variety of options to employ an MRP system which does not require the high maintenance overhead which is currently required by prior art MRP systems.

Accordingly, one aspect of the present invention is to provide a computer system for controlling the production, including pricing, costing, scheduling etc., of manufactured items having means for receiving and storing production information and means for interrogating the stored production information and using the result of such interrogation to create a parameter table containing selected production information and utilizing calculations based on the information from the parameter table to control the production of the manufactured items.

Another aspect of the present invention is to provide a computer system for controlling the production, including pricing, costing, scheduling etc., of manufactured items having means for receiving and storing production information and means for interrogating the stored production information and using the result of such interrogation to create a parameter table containing selected production information and utilizing calculations based on the information from the parameter table to control the production of the manufactured items, wherein the user may define formulas for the calculations to be performed utilizing the parameter table.

Still another aspect of the present invention is to provide a computer system for controlling the production, including pricing, costing, scheduling etc., of manufactured items having means for receiving and storing production information and means for interrogating the stored production information and using the result of such interrogation to create a parameter table containing selected production information and utilizing calculations based on the information from the parameter table to control the production of the manufactured items, wherein the system is selectively operable between pre-determined and user-defined formulas for the calculations to be performed utilizing the parameter table.

These and other aspects of the present invention will more clearly understood after review of the following description of the preferred embodiment of the invention when considered with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generalized block diagram of a programmable computer system suitable for implementing the exemplary embodiment of the present invention;

FIG. 2 is a generalized flow chart illustrating the relationship between the program modules of the present invention;

FIG. 3 is a schematic diagram representing the data structure in a computer system implementing the present invention;

FIG. 4 is a generalized flow chart illustrating the sequence of operations performed by the machine for the sales order entry module;

FIG. 5 is a generalized flow chart illustrating the sequence of operations performed by the machine for the inventory control module;

FIG. 6 is a generalized flow chart illustrating the sequence of operations performed by the machine for the purchasing module;

FIG. 7 is a generalized flow chart illustrating the sequence of operations performed by the machine for the estimating and standards module;

FIG. 8 is a generalized flow chart illustrating the sequence of operations performed by the machine for the work order control module;

FIG. 9 is a generalized flow chart illustrating the sequence of operations performed by the machine for the MRP module;

FIG. 10 is a detailed flow chart illustrating the process of Product Standards Entry/Change shown in FIG. 7;

FIG. 11 is a detailed flow chart illustrating the process of Detail Formula Entry/Change shown in FIG. 7;

FIG. 12A is a detailed flow chart illustrating the process of Estimate Entry/Change shown in FIG. 7;

FIG. 12B is a continuation of the detailed flow chart shown in FIG. 12A illustrating the function block for Copying the Product Standard Detail Records;

FIG. 13A is a detailed flow chart illustrating the process of Estimate Calculation shown in FIG. 7;

FIG. 13B is a continuation of the detailed flow chart shown in FIG. 13A illustrating the process of Estimate Calculation shown in FIG. 7; and

FIG. 14 is a detailed flow chart illustrating the process of Formula Processing shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in general and to FIG. 1 in particular, it will be understood that the illustrations are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the invention thereto.

FIG. 1 provides a block diagram of a typical computer system 10 programmed in accordance with this invention. In the exemplary embodiment, the system 10 includes as "hardware" a Data General model MV/2500 computer and, as "software", a commercially available operating system suitably programmed to execute COBOL program instructions in accordance with this invention.

Typically, such a computer system 10 includes a processor unit 12 having human interfaces via a CRT display 14 and a manually activated keyboard 16. A disk store 18 conventionally includes a data base of, for example, inventoried fabric pieces and associated color, length, location, etc. parameters which can be readily machine accessed by the processor 12 under suitable program control. A RAM 20 is typically also included for program storage. A suitable hard copy output device 21 can be used to generate a permanent record. However, it should be understood that the spirit of the invention can also be performed by hard-wired circuitry or a special purpose computer. Such devices contain the same basic elements which are utilized when instructed by a software program according to the present invention. Consequently, the scope of the present invention is intended to be determined according to the following claims and not by the particular embodiment described herein.

Keeping this in mind, the present invention will be described in connection with how a general purpose computer can be programmed and operated to achieve the objectives of the present invention. From the following detailed description one skilled in the art will be readily capable of generating the specific instruction set for programming the computer to perform the desired operations.

In the present invention, the stored program within RAM 20 will include a program for generating the BOM in accordance with this invention. It will be appreciated that the portions of such RAM which store program segments directed toward accomplishment of a particular function will necessarily constitute a portion of the provided apparatus of "means" for achieving that same respective function in this exemplary embodiment.

In the preferred embodiment, the MRP system of the present invention includes an unique means of processing the BOM which allows the user to specify for each line of the BOM the type of calculation which is to be performed either: 1) "default" which is defined as the parts quantity times the production quantity or 2) a formula calculation which can be any calculation based on the information in any of 150 fields stored in a parameter table.

When the user sets up a BOM in the MRP system of the present invention, it has the option of specifying for each detail of the BOM the following information:

a) "Default" or "formula calculation" (if "formula", then the user specifies the formula code to be executed).

b) The materials item code which can be changed by the formula.

c) The quantity of the item, per unit of output (this value can also be changed by the formula).

In each of the modules in which BOM processing occurs, Estimating and Standards, MRP, and Work Order Control, the MRP system of the present invention performs the following:

a) Sets up the parameter table.

b) Default calculation or formula calculation as requested by the user.

c) Moves selected fields back to the appropriate record (i.e., cost detail, MRP detail, or Work Order Detail) from the parameter table).

FIG. 2 illustrates the overall relationship between the modules which comprise the MRP system of the present invention. The modules are Sales Order Entry 22, Inventory Control 24, Purchasing 26, Estimating and Standards 28, Work Order Control 30 and MRP 32 and are described briefly below. The six modules are written in COBOL and, in the preferred embodiment, interface with a General Ledger 34, Accounts Receivable 36, Accounts Payable 38, and Payroll 40 system available from SouthWare Innovations, Inc., Auburn, Ala.

1. Sales Order Entry Module

The Sales Order Entry Module 22 allows the user to enter sales orders, ship stock against those orders, and produce invoices for shipped orders. It also has the capability to produce after-the-fact invoices. During order entry, credit checking is performed and a Sales Acknowledgement may be printed. The Sales Order Entry Module 22 has the capability to assign orders to truck loads based on user-defined load capacity calculations (e.g., cubic feet, square feet, weight, etc) . Orders may be entered for items which are shipped from stock, drop shipped by a vendor, or customer manufactured items. They may be for items which are tracked by serial number, lots, or items with options. The Sales Order Entry Module 22 also includes customer invoicing. Invoices may be produced for items which have been shipped or for jobs which were entered into the Work Order Control Module. The Sales Order Entry Module 22 interfaces with the Inventory Control 24, Purchasing 26, Work Order Control 30, MRP 32, Accounts Receivable 36 and General Ledger 34 modules.

2. Inventory Control Module

The Inventory Control Module 24 allows the user to track finished goods and/or raw material inventory. The Inventory Control Module 24 supports multiple warehouse locations. Items in inventory may be divided into categories which is useful in sales analysis. Furthermore, the user can specify that items in a category may have up to six (6) different options. Each of these options may have user-defined description and editing characteristics. The Inventory Control Module 24 maintains an inventory balance for each item or item/option combination. It relieves inventory during invoicing and issuing materials to work orders. It handles purchase orders, receipts, physical inventory counts, and adjustments. Items may be tracked in inventory by serial number or lot number. The Inventory Control Module 24 also includes three types of inventory commitment and reorder techniques. Items may be committed to a sales order or a stock level, custom, or net requirements basis.

3. Purchasing Module

The Purchasing Module 26 aids the user in issuing purchase orders as well as monitoring receipts. The Purchasing Module 26 first produces a recommended purchase list. It automatically prints the purchase order, if desired, and monitors open purchase orders until they are received. The cost of purchased items may be entered at a later date. The Purchasing Module 26 interfaces with the Accounts Payable 38, Inventory Control 24, Sales Order Entry 22, MRP 32 and Work Order Control 30 modules.

4. Estimating and Product Standards Module

The Estimating and Product Standards Module 28 allows the user to estimate the cost of a "one time" job or to establish standards for products which are manufactured on a repetitive basis. The Estimating and Product Standards Module 28 defines the labor, material, outside services and other direct costs used to build a product. This module also allows the user to define standard operations which may be used across several products or jobs but which have independent standards. The Estimating and Product Standards Module 28 allows the user to define flexible, formula based Product Standards. Both usage and direct costs may be values which the user specifies as part of the Product Standards or they may be calculated by user-defined formulas. The Estimating and Product Standards Module 28 optionally calculates manufacturing and general and administrative overhead costs. It may also be used to estimate a selling price based on up to four (4) user-defined pricing methods formulas for each of four different production quantities.

5. Work Order Control Module

The Work Order Control Module 30 allows the user to enter work orders into the system and to track them until they are completed. An order may be based on a Product Standards, an estimate, or may be a "one time" order. The user also may select shop scheduling. This module supports either a plant or department level calendar and allows the user to specify machine and employee capacity by work center. Work orders may be scheduled using either forward or backward scheduling. It produces a wide variety of production documents and lists, including production pickets and a material list. The Work Order Control Module 30 tracks work through the plant. Actual labor and material usage may be reported, or it may be taken as standard. The Work Order Control Module 30 tracks direct costs, manufacturing overhead costs as well as general and administrative overhead costs. It includes reports and inquiry screens which compare the actual cost to the standard or estimated costs.

6. MRP Module

The MRP Module 32 allows the user to forecast material and capacity requirements necessary to meet the Sales and Production Plan during each of the periods in the planning horizon. It produces an Exception Report which identifies resource shortages with respect to the current production schedule. It also produces a planned Purchase Order list and Planned Work Order List which represent the order requirements for the current plan. The MRP Module 32 interfaces with the Work Order Control 30, Estimating and Standards 28, Inventory Control 24, and Purchasing 26 modules. It may also be adapted to interface with optional Sales Forecasting 42 and Production Planning 44 modules.

As best seen in FIG. 3, a schematic diagram representing the data structure in a computer system implementing the present invention is shown. The primary files, discussed in more detail later, are each accessible by two or more of the modules of the present invention. Each of the primary files are accessible by the MRP Module 32 which integrates the contents of the primary files and selected secondary files (not shown).

Turning now to FIG. 4, the details of the Sales Order Entry Module 22 are illustrated. The primary file used by the Sale Order Entry Module 22 is Sales Order File 42. In the preferred embodiment, the Sales Order Entry Module 22 offers the user two alternatives for processing sales orders. "One step" invoicing is the simplest and involves the direct entry or orders for invoicing. The other alternative, "two-step" processing, allows the user to enter orders, print acknowledgements, generate production and/or shipping documents, then produce invoices. Both alternatives may be used concurrently.

The user may produce a variety of different kinds of orders, including drop shipments, transfer orders from one warehouse to another, credit memos and billing adjustments. During sales order entry, the user may search for a customer by the customer number, index lookup, or alphanumeric (customer name) search. Additionally, the user may add a new customer during order entry without having to exit the program and return to a menu.

The user also may assign multiple ship-to addresses to each customer. When entering orders, the user may select the same ship-to as the billing address, or enter the code for one of the alternate ship-to addresses for the customer. The user also may use up to six user-defined options for each item. Use of the valid option checking feature insures that an acceptable value will be entered for each option at order entry. The Sales Order Entry Module 22 checks stock availability during order entry. If stock is not available, the user will have the option of shipping available stock, creating a back order, cancelling the order line, or entering a substitute item.

Shipping dates may be assigned by order header or by detail line, allowing the user to use different shipping dates for each line on an order. The user may use comments on documents produced by the system, including sales orders, purchase orders, bills of lading, production documents, and invoices. The user also may specify whether the comment is for internal use, or the user may set up standard, or recurring comments to reduce data entry.

The Sales Order Entry Module 22 includes an automatic credit checking feature which allows the user to assign a credit limit and credit expiration date for each customer. During order entry, the Sales Entry Order Module 22 checks credit availability for the customer and places a credit hold on the order if sufficient credit is not available. The user may take advantage of the Truck Load processing feature if the user deliver orders on company trucks, ship in complete truck loads, or need to group orders together for processing.

The Sales Order Entry Module 22 offers an easy to use order inquiry program which is designed for use by customer service representatives who take telephone inquiries from customers. The inquiry offers several alternative ways to locate an order and shows up to date information at several levels of detail.

An UPS processing feature automatically calculates UPS charges, adds them to the order, and prints the UPS manifest. It can handle air shipments as well as COD and other special charges. Packing tickets may be generated by bin location to facilitate selection of stock for shipment.

Sales commission calculations may be either default or formula based calculations based on commission rates for each customer, order shipping address, order or item. In addition, the system handles multi-salesman commission splitting for up to a four way split.

The Sales Order Entry Module 22 allows the user to set up a cross reference table for entering orders using the manufacturing operation customer's items numbers, categories, and descriptions. The customer-defined information will be printed on documents produced for the customer, while the standard item number and description are printed on documents for internal use. This cross reference table also allows the user to establish special pricing for this customer.

The Sales Order Entry Module 22 allows for the use of royalty calculations with user-defined formulas. Item pricing and/or discounting may be handled using formulas, tables, or item pricing. The customer type determines how pricing will be applied for each customer, allowing the user to use different methods for different customers.

Turning now to FIG. 5, the Inventory Control Module 24 is shown. The Inventory Control Module 24 allows the user to maintain inventory records for multiple warehouses or locations. If the same item is found in more than one location, the system maintains information separately for each physical location. The Inventory Control Module 24 allows the user to maintain records concurrently for a variety of different items types, including:

a) Serial Items--items for which it is necessary to maintain a serial number identification for each occurrence in inventory.

b) Lot or Bin--Items which require identification by lot grouping or bin placement within a physical location.

c) Option--Items which have assigned options such as color or size. The MRP system of the present invention has the ability to maintain up to six different options for each category of items.

d) Regular--Items for which none of the above conditions apply.

The Inventory Control Module 24 has several features to facilitate the processing of a physical inventory. For recording physical counts, the Inventory Control Module 24 prints work sheets by location and in a variety of sequences. To ease entry of counted figures, the Inventory Control Module 24 prompts the operator for each entry in the same sequence that the work sheet was printed. Before updating the inventory quantities, the Inventory Control Module 24 operates a comparison printout of the old and new figures. Discrepancies may be checked and corrected before updating the physical count results.

Inventory adjustments are made by the Inventory Control Module 24 in a three-step process which insures an audit trail of all entries. The first step is the entry of inventory adjustments. The second step is the printing of an edit list or entry register. After verification, and corrections if necessary, the adjustments are posted, completing the process. The Inventory Control Module 24 has inquiry capability tailored to the item, and providing up to date information at several levels of detail.

The Inventory Item File 44 utilized by the Inventory Control Module 24 includes raw materials as well as finished products, eliminating the need to maintain separate files. The Inventory Item File 44 contains three different costs for each item: standard cost, last cost and average cost. The last cost and average cost values are automatically updated by the Inventory Control Module 24 each time the item is received into inventory. Inventory costing may be based on any of these three costs.

The Inventory Control Module 24 allows Item pricing based on one of five different price levels maintained in the item file. The system offers several calculation programs to automatically recalculate item pricing. Information about item acquisition is maintained through the Item Source file. There are several different source types, including Vendor for purchased items, Plant for manufactured items, and Locations for items received through an inventory transfer. Multiple sources and source types may be maintained for each inventory item.

As best seen in FIG. 6, the Purchasing Module 26 aids the user in issuing purchase orders as well as monitoring receipts. The primary file used by the Purchasing Module 26 is the Purchase Order File 46. The Purchasing Module 26 first produces a recommended purchase list. It automatically prints the purchase order, if desired, and monitors open purchase orders until they are received. The cost of purchased items may be entered at a later date. The Purchasing Module 26 interfaces with the Accounts Payable 38, Inventory Control 24, Sales Order Entry 22, MRP 32 and Work Order Control 30 modules.

Turning now to FIG. 7, the Estimating and Product Standards Module 28 is illustrated. The primary file used by the Estimating and Product Standards Module 28 is the Product Standards File 48. This file is similar to a traditional BOM, in that it specifies the exact components of production required to make a product. These components of production may include Materials, Labor, Outside services, and up to seven user-defined Other costs. However unlike the prior art, the Estimating and Product Standards Module 28 also has the ability to use either default methods or formulas for calculating Quantities, Costs, Lead Times, and Overhead. Formulas may be entirely user-defined and may consider any of up to 150 variables from the files used by the Estimating and Product Standards Module 28.

The Product Standards records used for MRP planning also may easily be copied into either estimates or work orders. From an estimate, costing, pricing, and inventory requirements are calculated. From a work order, inventory is reduced, production documents are generated, and actual costs are charged as they are incurred. Overhead costs may be considered in estimate calculation using any of a variety of user-defined alternatives, including formulas. The user also may maintain estimates for regular production items as well as special or custom items, and multiple estimates may be maintained for each item.

Another important file maintained through the Estimating and Product Standards Module 28 is the Standard Operations File 50. The Standard Operations File 50 includes procedures, labor operations, miscellaneous cost items, or comments which are recurring and may be required for multiple products or items that the user want to build. Each Standard Operations item may be used several times in building a product, and/or it may be used in building many different products. The Standard Operations File 50 allows the user to make changes to the Standard Operations record to update all the different Product Standards which use the operation.

The Estimating and Product Standards Module 28 allows estimates to be easily changed, calculated, or copied. This gives the user the ability to easily examine the impact of changes in the various components of production required to make a product. Each estimate may include pricing for up to four different manufacturing quantities, allowing the user to examine the efficiencies achieved with different volumes.

As best seen in FIG. 8, the Work Order Control Module 30 is illustrated. The primary file used by the Work Order Control Module 30 is the Work Order File 54.

Work orders are generated as part of a three-step process in which they are entered, edited and posted. Each Work Order record consists of a header and one or more detail lines. The Work Order detail lines are identical in structure to the Product Standards detail records. When creating work orders, the user has the option of duplicating the Product Standards records as Work Order detail lines. Changes can then be made to the Work Order detail lines without affecting the Product Standards record.

The Work Order Control Module 30 allows the user to establish default overhead and labor rates by plant, department, or work center. The setting of the manufacturing operation control record determines in which of these files the default rates will be established, insuring the user the most meaningful default values. The default rates may be overridden for specific work orders during work order processing.

The Work Order Control Module 30 also allows the creation of a customized calendar which is used for production scheduling. The manufacturing operation control record determines whether the calendar is to be established by plant or by department. The calendar specifies standards work days and hours, as well as exceptions such as holidays. The Work Order Control Module 30 allows the use of up to 9 reporting stations within each plant. Reporting stations are sequential checkpoints at which manufacturing progress is reported to the system.

Quantities of labor, materials, and other items used in the manufacturing process may be reported to the MRP system of the present invention at actual or standard usage. If reporting is to be done at actual, then the quantities must be monitored and entered. If reporting is to be done at standard, then the standard quantity will always be used for relieving inventory and calculating costs. Each work order may have some items which are reported at standard and some reported at actual, or all items on a work order may be reported at either standard or actual.

For each Work Order detail line, the Work Order Control Module 30 maintains both estimated and actual quantities and costs. Estimated amounts are calculated from the Work Order detail lines when the work order is posted, and these figures are used for committing inventory and scheduling. Actual amounts are calculated after reporting occurs for the Work Order detail line regardless of whether reporting is done at actual or standard. The Work Order Control Module 30 maintains both figures for comparison.

The Work Order Control Module 30 has the capability of generating work orders from sales orders using the Auto Entry option. In addition to reducing the amount of data entry required to generate a work order, this links the work order record with the sales order for which it was generated.

All quantity and cost calculations performed by the Work Order Control Module 30 may be based on the default or the formula method. In most situations, the default method is adequate, but the formula method provides a very powerful tool in complex situations where many factors must be considered.

The Work Order Control Module 30 tracks and places into inventory, defective items which are generated as part of the manufacturing process.

Work Order inquiries show Work Order header and detail information, including status, estimated costs, and estimated quantities in a similar manner as shown in Table 2. Work Order inquiry also displays up to date actual costs and quantities which have been posted.

As discussed above, the MRP Module 32 allows the user to forecast material and capacity requirements necessary to meet the Sales and Production Plan during each of the periods in the planning horizon. It produces an Exception Report which identifies resource shortages with respect to the current production schedule. It also produces a planned Purchase Order list and Planned Work Order List which represent the order requirements for the current plan.

MRP planning may be performed in either of two modes: net change or regenerative. Net change is the process of determining the change in material and capacity requirements which results from changes in demand, supply, and on hand balances which have occurred since the last time the MRP system was updated.

In regenerative MRP planning the MRP detail files are first deleted and then rebuilt from existing sales orders, purchase orders and work orders. The MRP records contain the quantity of demand for each sales order and work order detail record or the quantity of supply for each purchase order or work order header record. The MRP records are stored by Inventory Item number in date and time due sequence. Each Inventory Item record which contains either supply or demand is automatically flagged for MRP planning.

As best seen in FIG. 9, the regenerative MRP planning operation is illustrated. The MRPA, MRPB, MRPC, and MRPD blocks perform the copying functions, as discussed above, to rebuild the MRP records. Then the MRPE block performs the time phased netting operation. Each record in the Inventory Item File 44 is processed until a complete pass is made through the Inventory Item File 44 without detecting a flagged item. Each flagged record in the Inventory Item File 44 is processed with its corresponding MRP record in date and time sequence. For each MRP record a new balance is first calculated. If the value of the new balance is less than the value of an user-defined safety margin value for that particular item, then a new record is written to the Requirements File that indicates that a purchase order for purchased items or a work order for manufactured items is to be issued or changed.

When a work order is to be issued or changed, the MRPF block explodes the requirement for the item, according to the definition in the Product Standards File 48, and writes it to the MRP detail file. The same default or user-defined calculations as used by the Estimating and Product Standards Module 28 and the Work Order Control Module 30. As additional requirements for items are written into the MRP detail file, the corresponding Inventory Item record is flagged.

As can be understood from the above discussion, the MRP system of the present invention allows the user to control the calculations utilized by the system. Thus, the user may select either default or user-defined formula calculations for each of the following:

(1) Customer Pricing;

(2) Customer Discounts;

(3) Truck Capacities;

(4) Salesmen Commissions;

(5) Designer Royalties; and

(6) Product Standards/Estimate/Work Order/MRP detail quantity and cost calculations.

The formulas operate on the "universe" of information which is stored in a parameter table which is unique for each of the above. For example, the parameter table for Customer Pricing contains Customer Type, Customer Sold To, Customer Ship To, and Salesman information. However it does not contain information about components of production. On the other hand, the parameter table for calculating Estimate details does not contain Customer information. For each of the above, both the default and formula calculations are performed utilizing the information in its associated parameter table.

The instruction set for the user-defined formulas for each of the above are identical. The instructions are stack-oriented and utilize "reverse Polish" notation. The formula instruction set allows a degree of user programming and includes "If", "Then", "Else", and "Perform" operations.

For the purpose of illustrating its operation, the use of formulas in the Estimating and Product Standards Module 28 will be discussed in more detail, however, this discussion is equally applicable to any module employing the formula function such as listed above.

Turning now to FIG. 10, a detailed flow chart illustrating the process of Product Standards Entry/Change, shown in FIG. 7, is shown. A discussion of its operation follows:

Product Standards File Maintenance

The Product Standards File 48 of the MRP system of the present invention are similar to traditional BOM records, in that they specify the exact production components that are used to build a product. Product Standards records are the basis for standard cost calculations, production scheduling and capacity planning, material requirements planning, and generating production documents. Within the Estimating and Product Standards Module 28, the Product Standards records may be used to process estimates. On the other hand, in the Work Order Control Module 30, the Product Standards records are generally the basis of work orders.

There are several different types of production components that may be specified by the Product Standards File 48. The manufacturing operation control record indicates which ones are used by the manufacturing operation. Each Product Standards record consists of two components, a Product Standards header and the Product Standards detail records. Each Product Standards record may contain multiple detail records.

The header screen appears as shown below:

                  TABLE 1
    ______________________________________
    Standard Header File MaintTIME 15:54 TERM 8
    ______________________________________
     ##STR1##
     ##STR2##
     ##STR3##
     ##STR4##
     ##STR5##
     ##STR6##
    ______________________________________

                  TABLE 2
    ______________________________________
    Product Standards Detail File MaintTIME 15:57 TERM 8
    ______________________________________
     ##STR7##
     ##STR8##
     ##STR9##
     ##STR10##
     ##STR11##
     ##STR12##
     ##STR13##
     ##STR14##
     ##STR15##
     ##STR16##
    Standard Calc Parameters:
     ##STR17##
     ##STR18##
     ##STR19##
     ##STR20##
     ##STR21##
     ##STR22##
     ##STR23##
     ##STR24##
     ##STR25##
     ##STR26##
    ______________________________________

                  TABLE 3
    ______________________________________
    Detail Cost Formula File MaintTIME 10:50 TERM 3
    ______________________________________
     ##STR27##
     ##STR28##
     ##STR29##
     ##STR30##
     ##STR31##
    ______________________________________

                  TABLE 4
    ______________________________________
    FAB01 00 0010 01 01 01 00000000.000000 01
                                  01     00 0000
    FAB01 00 0020 01 77 01 00000000.000000 02
                           1040   01     00 0000
    FAB01 00 0025 01 78 01 00000000.000000 01
                                  01     00 0000
    FAB01 00 0026 01 77 01 00000000.000000 02
                           1040   01     00 0000
    FAB01 00 0030 01 47 02 00000001.000000 02
                           1040   01     00 0000
    FAB01 00 0040 01 83 01 00000000.000000 01
                                  02 T   00 0000
    ______________________________________

                  TABLE 5
    ______________________________________
    Est & Stds Detail Formula MaintTIME 17:23 TERM 25
    ______________________________________
     ##STR32##
     ##STR33##
     ##STR34##
     ##STR35##
     ##STR36##
     ##STR37##
    3. Operand
     ##STR38##
    ______________________________________

                  TABLE 6
    ______________________________________
    Param Parameter           Set By     Read By
    No    Name         Ty     Sys  Frm  Oper Sys  Frm
    ______________________________________
     1    Est/WO Item to
                       A      Y                   Y
          be Mfg
     2    Est/WO Router
                       A      Y                   Y
          Code
     3    Est/WO Item  A      Y                   Y
          Category
     4    Est/WO Option 1
                       E      Y                   Y
     5    Est/WO Option 2
                       E      Y                   Y
     6    Est/WO Option 3
                       E      Y                   Y
     7    Est/WO Option 4
                       E      Y                   Y
     8    Est/WO Option 5
                       E      Y                   Y
     9    Est/WO Option 6
                       E      Y                   Y
     10   Est/WO User  A      Y                   Y
          Option 1
     11   Est/WO User  A      Y                   Y
          Option 2
     12   Est/WO User  N      Y                   Y
          Value 1
     13   Est/WO User  N      Y                   Y
          Value 2
     14   Est/WO Total N      Y                   Y
          Qty to Mfg
     15   Est/WO Lead  N      Y                   Y
          Time
     16   Mfg Item Record
                       B      Y                   Y
          Flag
     17   Mfg Item Unit of
                       A      Y                   Y
          Measure
     18   Mfg Item Unit
                       N      Y                   Y
          Weight
     19   Mfg Item     N      Y                   Y
          Average Cost
     20   Mfg Item Last
                       N      Y                   Y
          Cost
     21   Mfg Item     N      Y                   Y
          Standard Cost
     22   Mfg Item Width
                       N      Y                   Y
          Per Unit
     23   Mfg Item Height
                       N      Y                   Y
          Per Unit
     24   Mfg Item Length
                       N      Y                   Y
          Per Unit
     25   Mfg Item User
                       A      Y                   Y
          Option -1
     26   Mfg Item User
                       A      Y                   Y
          Option -2
     27   Mfg Item User
                       N      Y                   Y
          Value -1
     28   Mfg Item User
                       N      Y                   Y
          Value -2
     29   Est/WO Detail
                       B      Y                   Y
          Record Flag
     30   Est/WO Detail
                       A      Y                   Y
          Type
     31   Est/WO Detail
                       A      Y    Y              Y
          Dept Code
     32   Est/WO Detail
                       A      Y    Y              Y
          Work Center
     33   Est/WO Detail
                       A      Y    Y              Y
          Item
     34   Est/WO Detail
                       N      Y    Y              Y
          Item Whse
     35   Est/WO Detail
                       A      Y    Y              Y
          Oper/Mod
     36   Est/WO Detail
                       N      Y                   Y
          Setup/Scrap
     37   Est/WO Detail
                       N      Y                   Y
          Freq
     38   Est/WO Detail
                       N      Y                   Y
          Run Time/Qty
     39   Est/WO Detail
                       A      Y                   Y
          U/M
     40   Est/WO Detail
                       N      Y                   Y
          Rate/Cost
     41   Est/WO Detail
                       A      Y                   Y
          Pay Type
     42   Est/WO Detail
                       N      Y                   Y
          Move Time
     43   Est/WO Detail
                       N      Y                   Y
          Queue Time
     44   Est/WO Detail
                       N      Y                   Y
          Overlap %
     45   Est/WO Detail
                       N      Y                   Y
          User Value
     46   Est/WO Detail
                       N      Y                   Y
          Qty Compl
     47   WT Record Flag
                       B      Y                   Y
     48   WT Type      A      Y                   Y
     49   WT Dept Code A      Y                   Y
     50   WT Work Center
                       A      Y                   Y
     51   WT Item      A      Y                   Y
     52   WT Item Whse N      Y                   Y
     53   WT Oper/Cat  A      Y                   Y
     54   WT Serial    A      Y                   Y
          Number
     55   WT Vendor    N      Y                   Y
          Number
     56   WT Setup Time/
                       N      Y                   Y
          Scrap
     57   WT Run Time/ N      Y                   Y
          Quantity
     58   WT Unit of   A      Y                   Y
          Measure
     59   WT Cost per Unit
                       N      Y                   Y
     60   WT Employee  N      Y                   Y
          No
     61   WT Shift     N      Y                   Y
     62   WT Pay Type  A      Y                   Y
          Code
     63   WT Quantity  N      Y                   Y
          Completed
     64   WT Quantity  N      Y                   Y
          Scrap
     65   Company GNA  N      Y                   Y
          Overhead Rate
     66   Plant Code   A      Y                   Y
     67   Plant Def RM N      Y                   Y
          Item Whse
     68   Plant Def FG N      Y                   Y
          Item Whse
     69   Plant Mfg    N      Y                   Y
          Overhead Rate
     70   Plant Reg Labor
                       N      Y                   Y
          Rate
     71   Plant Ovt Labor
                       N      Y                   Y
          Rate
     72   Plant Spc Labor
                       N      Y                   Y
          Rate
     73   Plant User   N      Y                   Y
          Value 1
     74   Plant User   N      Y                   Y
          Value 2
     75   Plant User   N      Y                   Y
          Value 3
     76   Dept Record Flag
                       B      Y         81        Y
     77   Dept Mfg Over-
                       N      Y         81        Y
          head Rate
     78   Dept Reg Labor
                       N      Y         81        Y
          Rate
     79   Dept Ovt Labor
                       N      Y         81        Y
          Rate
     80   Dept Spc Labor
                       N      Y         81        Y
          Rate
     81   Dept User    N      Y         81        Y
          Value 1
     82   Dept User    N      Y         81        Y
          Value 2
     83   Dept User    N      Y         81        Y
          Value 3
     84   Work Center  B      Y         82        Y
          Record Flag
     85   Work Center Mfg
                       N      Y         82        Y
          Ovhd Rate
     86   Work Center Def
                       A      Y         82        Y
          Pay Type
     87   Work Center Reg
                       N      Y         82        Y
          Labor Rate
     88   Work Center Ovt
                       N      Y         82        Y
          Labor Rate
     89   Work Center Spc
                       N      Y         82        Y
          Labor Rate
     90   Work Center  N      Y         82        Y
          User Value 1
     91   Work Center  N      Y         82        Y
          User Value 2
     92   Work Center  N      Y         82        Y
          User Value 3
     93   Item Record Flag
                       B      Y         83        Y
     94   Item Unit of A      Y         83        Y
          Measure
     95   Item Unit Weight
                       N      Y         83        Y
     96   Item Average N      Y         83        Y
          Cost
     97   Item Last Cost
                       N      Y         83        Y
     98   Item Standard
                       N      Y         83        Y
          Cost
     99   Item Width Per
                       N      Y         83        Y
          Unit
    100   Item Height Per
                       N      Y         83        Y
          Unit
    101   Item Length Per
                       N      Y         83        Y
          Unit
    102   Item User    A      Y         83        Y
          Option -1
    103   Item User    A      Y         83        Y
          Option -2
    104   Item User    N      Y         83        Y
          Value -1
    105   Item User    N      Y         83        Y
          Value -2



    106   Serial Record
                       B      Y         83        Y
          Flag
    107   Serial Unit of
                       A      Y                   Y
          Measure
    108   Serial Unit Cost
                       N      Y                   Y
    109   Serial Standard
                       N      Y                   Y
          Cost
    110   Serial Type  A      Y                   Y
    111   Serial MRP Rel
                       A      Y                   Y
          Type
    112   Stnd Op Record
                       B      Y         84        Y
          Flag
    113   Stnd Op Setup
                       N      Y         84        Y
          Time/Scrap
    114   Stnd Op      N      Y         84        Y
          Frequency
    115   Stnd Op Run  N      Y         84        Y
          Time/Quantity
    116   Stnd Op Unit A      Y         84        Y
          of Measure
    117   Stnd Op Cost per
                       N      Y         84        Y
          Unit
    118   Stnd Op Pay  A      Y         84        Y
          Type
    119   Stnd Op Move N      Y                   Y
          Time
    120   Stnd Op Queue
                       N      Y                   Y
          Time
    121   Stnd Op      N      Y                   Y
          Overlap %
    122   Stnd Op User N      Y                   Y
          Value
    123   Employee Record
                       B      Y                   Y
          Flag
    124   Employee Reg N      Y                   Y
          Rate
    125   Employee Ovt N      Y                   Y
          Rate
    126   Employee Spc N      Y                   Y
          Rate
    127   Employee     A      Y                   Y
          Classification
    128   User Defined -1
                       E           Y              Y
    129   User Defined -2
                       E           Y              Y
    130   User Defined -3
                       E           Y              Y
    131   User Defined -4
                       E           Y              Y
    132   User Defined -5
                       E           Y              Y
    133   Reserved
    134   Reserved
    134   Reserved
    135   Reserved
    136   Reserved
    137   Reserved
    138   Eng Value 1  N      Y    Y         Y    Y
    139   Eng Value 2  N      Y    Y         Y    Y
    140   Eng Value 3  N      Y    Y         Y    Y
    141   Eng Value 4  N      Y    Y         Y    Y
    142   Eng Value 5  N      Y    Y         Y    Y
    143   Total Setup/ N      Y    Y         Y    Y
          Scrap
    144   Total Time/  N      Y    Y         Y    Y
          Quantity
    145   Total Direct Cost
                       N      Y    Y         Y    Y
    146   Gross Pay    N      Y    Y         Y    Y
    147   Mfg Overhead N      Y    Y         Y    Y
          Cost
    148   General and  N      Y    Y         Y    Y
          Admin Ovhd
    149   Total Wait Time
                       N      Y    Y         Y    Y
    150   Total Processing
                       N      Y    Y         Y    Y
          Time
    ______________________________________

                  TABLE 7
    ______________________________________
    Estimate Header File MaintTIME 8:59 TERM 8
    ______________________________________
     ##STR39##
     ##STR40##
     ##STR41##
     ##STR42##
     ##STR43##
    Quantities
     ##STR44##
     ##STR45##
     ##STR46##
     ##STR47##
    ______________________________________

                  TABLE 8
    ______________________________________
    Estimate Detail File MaintTIME 15:57 TERM 8
    ______________________________________
     ##STR48##
     ##STR49##
     ##STR50##
     ##STR51##
     ##STR52##
     ##STR53##
     ##STR54##
     ##STR55##
     ##STR56##
     ##STR57##
    Standard Calc Parameters:
     ##STR58##
     ##STR59##
     ##STR60##
     ##STR61##
     ##STR62##
     ##STR63##
     ##STR64##
     ##STR65##
     ##STR66##
    ______________________________________

                  TABLE 9
    ______________________________________
    FORMULA RETURN CODES
    RETURN
    CODE          DESCRIPTION
    ______________________________________
    01            Incompatible Formula
    02            Environmental Stack Overflow
    03            Environmental Stack Underflow
    04            Boolean Stack Overflow
    05            Boolean Stack Underflow
    06            Numeric Stack Overflow
    07            Numeric Stack Underflow
    08            Alpha Stack Overflow
    09            Alpha Stack Underflow
    10            Formula Not Found
    11            I-O Error on Formula File
    12            Missing End Block
    13            Divide by Zero Error
    14            Reserved Instruction
    15            Non-implemented Instruction
    16            Parameter No Out of Range
    ______________________________________

                  TABLE 10
    ______________________________________
    Sales Order Formula MaintTIME 17:23 TERM 25
    ______________________________________
     ##STR67##
     ##STR68##
     ##STR69##
     ##STR70##
    ______________________________________

                  TABLE 11
    ______________________________________
     ##STR71##
     ##STR72##
     ##STR73##
     ##STR74##
    ______________________________________

                  TABLE 12
    ______________________________________
    OP
    CODE   DESCRIPTION      OPERAND    STATUS
    ______________________________________
    01     Begin Block                 B
    Defines the start of block. This instruction does
    not alter NS, AS, or BS.
    02     End Block                   B
    Defines the end of block. This instruction does
    not alter NS, AS, or BS.
    03     Perform          L          B
    Executes the instruction or block at location
    designated by L. This instruction does not alter
    NS, AS, or BS.
    04     Perform While True
                            L          B
    Executes the instruction or block at location
    designated by L repeatedly if BS0 = "T"; This
    instruction does not alter NS, AS, or BS.
    05     Perform Until True
                            L          E
    Executes the instruction or block at location
    designated by L repeatedly if BS0 = "F"; This
    instruction does not alter NS, AS, or BS.
    06     Call             A          B
    Executes the formula designated by A. This
    instruction does not alter NS, AS, or BS.
    07     If True Then                B
    Executes the next instruction or block if BS0 =
    "T"; This instruction does not alter NS, AS, or
    BS.
    08     If Not True Then            E
    Executes the next instruction or block if BS0 =
    "F"; This instruction does not alter NS, AS, or
    BS.
    09     No Operation                B
    No Operation; This instruction does not alter ES,
    NS, AS, or BS.
    10     Push Immed Boolean
                            B          B
    Pushes the immediate boolean operand designated by
    B on BS; B to BS. This instruction does not alter
    ES, NS, or AS.
    11     And                         B
    Pops BS two times then pushes BS0 and BS1 on BS;
    BS0 and BS1 to BS. This instruction does not alter
    ES, NS, or AS.
    12     Or                          B
    Pops BS two times then pushes BS0 or BS1 on BS;
    BS0 or BS1 to BS. This instruction does not alter
    ES, NS, or AS.
    13     Not                         B
    Pops BS then pushes not BS0 on BS; Not BS0 to BS.
    This instruction does not alter ES, NS, or AS.
    14     Reserved                    R
    15     Table Boolean Next          U
    16     Table Boolean Random        U
    17     Push Bool Parameter
                            L          B
    Pushes the Lth element of the parameter table on
    BS; param(L) to BS. This instruction does not
    alter ES, NS, or AS.
    18     Pop Bool Parameter
                            L          B
    Pops BS into the Lth element of the parameter
    table; BS0 to param(L). This instruction does not
    alter ES, NS, or AS.
    19     Reserved                    R
    20     Push Immed Numeric
                            N          B
    Pushes the immediate numeric operand designated by
    N on NS; N to NS. This instruction does not alter
    ES, BS, or AS.
    21      Add                        B
    Pops NS two times then pushes NS1 plus NS0 on NS;
    NS1 + NS0 to NS; This instruction does not alter
    ES, BS, or AS.
    22     Subtract                    B
    Pops NS two times then pushes NS1 minus NS0 on NS;
    NS1 - NS0 to NS; This instruction does not alter
    ES, BS, or AS.
    23