Abstract:
A computer-readable recording medium recording a production management program that causes a computer to execute: a first process, based on a component table in which a group of components constituting a product is defined and on production planning information of the product, determining component planning information including a required period and a required quantity of each of the components; a second process linking the component planning information relating to each of the components within a certain period to an actual use record and recording it as first history information; a third process calculating a difference in the first history information recorded in chronological order and recording it as second history information; and a fourth process converting the second history information into a markup language and storing it, and searching and displaying the second history information on the basis of a specific component and period designated from outside.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of international PCT application No. PCT/JP2006/307675 filed on Apr. 11, 2006. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a production management technology, specifically to a technology that is effective when applied to excess inventory management, control and other such manipulation of components in production planning systems such as MRP (Material Resource Planning). 
   2. Description of the Related Art 
   In manufacturing processes of various products, the appropriate procurement of a variety of components that constitute the products is essential for the promotion of efficiency in the manufacturing processes. 
   For that reason, it is known that by employing an MRP technology such as that disclosed in Patent Document 1, a component procurement plan is prepared in line with the production plan of products, and the components can be distributed appropriately every week for example. It is also known that excess components are distributed to each of the manufacturing processes at the time of production plan preparation. 
   However, in actual manufacturing processes, various factors cause actual product quantities to vary from the product quantities specified during production plan preparation. For that reason, where the most suitable component distribution is performed on the basis of MRP every week, if excess components are produced within the period between production plan preparation and preparation of the next production plan and those components are of no use, the components become excess inventory. 
   In MRP, additionally, although the weekly most suitable result is output, factors causing the excess inventory are not considered at all. If a large number of components are used in every product and there is a deep hierarchical structure of inter-component dependency, appropriate control of such components of no use would not be feasible. 
   One possible solution to prevent the excess inventory of components is to prepare, for example, a daily or hourly production plan, which is a shorter time period than a weekly production plan; however, this is impossible in practice because the amount of information and calculation required for such production plan preparation is huge, and the procurement of components is quite complicated. 
   In the existing production management system in particular, a manager has to place orders for components trusting the production plan that is updated every week by MRP, and in cases such as when there is a large variety of components, a lengthy hierarchy of BOM (bills of material), and many common components, tracing the factor causing the excess components can be difficult if the excess components are included in the inventory assets, and making the decision of whether to hold or discard the components requires some time. 
   Patent Document 1 discloses a technology for pursuing a low cost and real-time production management system by constantly generating expansion constitution information that is the expansion of required quantities of each article number for each instructed article number, on the basis of component information representing information of a single article number, component table information representing the relationship between article numbers, and application information representing alterations in article numbers to be applied to a product. 
   Patent Document 2 discloses a technology for efficiently managing a design process for preparing the technical information of a drawing and the like by displaying the issue result of a drawing as a progress picture for each kind of machine of the product in accordance with a drawing issue plan set so as to procure parts on the basis of a production plan. 
   However, neither Patent Document 1 nor Patent Document 2 discloses the displaying of information required for analyzing the factors that caused the excess inventory of components. 
   Patent Document 1: 
   Japanese Patent Application Publication No. 2001-75629 
   Patent Document 2: 
   Japanese Patent Application Publication No. 2001-84020 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a production management technology that enables appropriate management of the factors and history of excess inventory of components constituting a product. 
   It is another object of the present invention to provide a production management technology that enables prompt and appropriate implementation of control of component excess inventory created in the production planning system. 
   It is a first aspect of the present invention to provide a production management program causing a computer to execute 
   a first process, based on a component table in which a group of components constituting a product is defined and on production planning information of the product, determining component planning information including a required period and a required quantity of each of the components, 
   a second process linking the component planning information relating to each of the components within a certain period to an actual use record and recording this as first history information, 
   a third process calculating a difference in the first history information recorded in chronological order and recording this as second history information, and 
   a fourth process converting the second history information into a markup language and storing it, and searching and displaying the second history information on the basis of a specific component and period designated from outside. 
   It is a second aspect of the present invention to provide a production management method comprising 
   a first process, based on a component table in which a group of components constituting a product is defined and on production planning information of the product, determining component planning information including a required period and a required quantity of each of the components, 
   a second process linking the component planning information relating to each of the components within a certain period to actual use records and recording this as first history information, 
   a third process calculating a difference in the first history information recorded in chronological order and recording it as second history information, and 
   a fourth process converting the second history information into a markup language and storing it, and searching and displaying the second history information on the basis of a specific component and period designated from outside. 
   It is a third aspect of the present invention to provide a production management system having a control logic comprising 
   storing means for storing a component table in which a group of components constituting a product is defined and production planning information of the product, 
   a first function for determining component planning information including a required period and a required quantity of each of the components on the basis of the component table and the production planning information, 
   a second function for linking the component planning information relating to each of the components within a certain period to actual use records and recording it as first history information in the storing means, 
   a third function for calculating a difference in the first history information recorded in chronological order and recording it as second history information in the storing means, and 
   a fourth function for converting the second history information into a markup language and storing it, and searching and displaying the second history information on the basis of a specific component and period designated from outside. 
   It is a fourth aspect of the present invention to provide a production management program causing a computer to execute processing of displaying information for specifying a cause of excess inventory of a component using second history information obtained as a difference that has occurred over time in first history information recorded by linking component plan information containing the required time period and required quantity of a component to actual use records of the component within a prescribed time period. 
   The present invention described above, when excess inventory of a component is found, can extract the history of fluctuations in the required quantity of the component from the second history information recorded periodically on the basis of the identification information of the component, and display fluctuations of the required quantity of the components; that is, display information for specifying a product that causes the excess inventory. In other words, it is possible to specify the point in time at which and the product plan under which the excess inventory component is ordered. In addition, it is possible to trace the point in time when a product plan is decreased or the product plan disappears and to trace the decreased or disappeared product plan. 
   By setting an appropriate threshold to the quantity of the excess inventory components and automatically extracting and displaying the excess inventory components that exceeded the threshold from the second history information recorded periodically, it is also possible to warn an administrator of the production management system about the creation of excess inventory. 
   As a result, the production management system administrator can make an appropriate judgment of an excess component disposal method on the basis of, for example, the cause of the excess inventory of the specified component. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram showing a conception of an example of a production management system configuration that is one of embodiments of the present invention; 
       FIG. 2  is a diagram showing an example of an MRP server configuration constituting the production management system that is one of embodiments of the present invention; 
       FIG. 3A  is a flowchart showing an example of operations of the production management system that is one of embodiments of the present invention; 
       FIG. 3B  is a flowchart showing an example of operations of the production management system that is one of embodiments of the present invention; 
       FIG. 3C  is a flowchart showing an example of operations of the production management system that is one of embodiments of the present invention; 
       FIG. 4  is a flowchart showing an example of operations of the production management system that is one of embodiments of the present invention; 
       FIG. 5A  is a diagram paired with  FIG. 5B  showing a conception of an example of the composition of and changes in various information files used in the production management system that is one of embodiments of the present invention; 
       FIG. 5B  is a diagram paired with  FIG. 5A  showing a conception of an example of the composition of and changes in various information files used in the production management system that is one of embodiments of the present invention; 
       FIG. 6A  is a diagram paired with  FIG. 6B  showing a conception of an example of the composition of and changes in various information files used in the production management system that is one of embodiments of the present invention; 
       FIG. 6B  is a diagram paired with  FIG. 6A  showing a conception of an example of the composition of and changes in various information files used in the production management system that is one of embodiments of the present invention; 
       FIG. 7  is a diagram showing a conception of an example of a change in an excess component search screen of a search terminal in the production management system that is one of the embodiments of the present invention; 
       FIG. 8  is a diagram showing a conception of an example of a change in an excess component search screen of a search terminal in the production management system that is one of the embodiments of the present invention; 
       FIG. 9  is a diagram showing a conception of an example of a change in an excess component search screen of a search terminal in the production management system that is one of the embodiments of the present invention; 
       FIG. 10  is a diagram showing a conception of an example of an electronic mail sent to a system administrator from the production management system that is one of the embodiments of the present invention; and 
       FIG. 11  is a diagram showing a conception of component requirement history data file accumulation process in the production management system that is one of the embodiments of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   In the following description, details of the embodiments of the present invention are set forth with reference to the drawings. 
     FIG. 1  is a diagram showing a conception of an example of a production management system configuration that is one of the embodiments of the present invention, and  FIG. 2  is a diagram showing an example of an MRP server configuration constituting the production management system of the present embodiment. 
   Additionally,  FIG. 3A ,  FIG. 3B ,  FIG. 3C  and  FIG. 4  are flowcharts showing an example of operations of the production management system of the present embodiment.  FIGS. 5A and 5B  and  FIGS. 6A and 6B  are diagrams showing a conception of an example of the composition of and changes in various information files used in the production management system of the present embodiment. 
   The production management system of the present embodiment comprises an MRP server  10 , a search server  20 , a director server  30 , a search terminal  40  and others, and these are connected to each other by an information network. 
   Note that in the following explanation, an example that implements the MRP server  10 , the search server  20  and the director server  30  in a separate computer is described; however, any two of those or all three maybe comprised in a single computer system. 
   The MRP server  10  performs production plan preparation in manufacturing processes of a product. The search server  20  accumulates information which is output from the MRP server  10  in a text format such as XML (Extensible Markup Language), and executes search processing of necessary information. The director server  30  executes processing of relaying a search request from the search terminal  40  to the search server  20 , and of responding the search result to the search terminal  40  in a text format such as XML. 
   As exemplified in  FIG. 2 , the MRP server  10  comprises a CPU (Central Processing Unit)  11 , main memory  12 , an external storage  13 , a network interface  14 , and an MRP database  50 . These are connected to each other by a bus  15 . 
   The CPU  11  controls the whole MRP server  10  by executing programs such as an operating system  16  stored in the main memory  12 . 
   The main memory  12  stores programs and data executed by the CPU  11 . In the case of the present embodiment, an MRP program  70  and a history information generation program  80  operating on the operating system  16  are stored. 
   The external storage  13  is a storage medium that realizes information-rewritable enduring storage of the information, and nonvolatile storage of information such as the operating system  16 , the MRP program  70 , and the history information generation program  80 , and these pieces of information are loaded from the external storage  13  to the main memory  12  at the startup of the MRP server  10 . 
   The network interface  14  controls information exchange with another director server  30  via an information network  18  such as a LAN. 
   The MRP database  50  comprises, for example, a transaction data file  51 , an apparatus configuration file  52 , a requirement data file  53 , a previous component cross tabulation data file  56  (first history information), a current component cross tabulation data file  57  (first history information), and a component requirement history data file  59  (second history information). 
   As exemplified in  FIG. 5A  and  FIG. 5B , in the apparatus configuration file  52 , subunits and configurations and quantities of components that constitute the product apparatus which is to be a subject of the production management are defined. The apparatus configuration file  52  stores information of a subunit/component name  52   b , a basic unit  52   c , a component name  52   d  and a basic unit  52   e , each of which corresponding to each apparatus name  52   a.    
   The transaction data file  51  is a file for recording the purchase (use) record of a component constituting each product apparatus defined in the apparatus configuration file  52 . A parent item  51   b , a quantity  51   c , a transaction content  51   d , and a transaction date  51   e  corresponding to each sub-item  51   a  are stored in the transaction data file  51   a.    
   The sub-item  51   a  is identification information given to individual components. The parent item  51   b  is identification information of a subunit or the product apparatus using the component as a constituent. The transaction content  51   d  is identification of an inbound component or an outbound component (e.g. delivery=outbound component). The transaction date  51   e  is the date when the component is actually used (delivered). 
   The requirement data file  53  is a file that the MRP program  70  generates on the basis of the production plan (production deadline, product quantity) of the product apparatus and information of the apparatus configuration file  52 . In the requirement data file  53 , in order to carry through with the production plan of the product apparatus, information of the number of components required and a deadline is stored. Specifically, for each sub-item  53   a  given to individual components, a parent item  53   b , required quantity  53   c , and requested date  53   d  are stored in the requirement data file  53 . 
   In the present embodiment, processing of comparing (cross tabulation) the requirement data file  53  in the production plan with the transaction data file  51  indicating the actual use record of components, generating the current component cross tabulation data file  57  and accumulating the files in chronological order, is carried out by the history information generation program  80 . 
   The current component cross tabulation data file  57  is accumulated in chronological order, and the file recorded before the current component cross tabulation data file  57  is the previous component cross tabulation data file  56 . The items in the previous component cross tabulation data file  56  are the same as those in the current component cross tabulation data file  57 . 
   The current component cross tabulation data file  57  comprises a sub-item  57   a , a parent item  57   b , a data creation date  57   c , and a required quantity in each period  57   d.    
   The sub-item  57   a  is identification information given to the individual components. The parent item  57   b  is identification information of a subunit or the product apparatus using the component as a constituent. The data creation date  57   c  is the date when the cross tabulation is executed. The required quantity in each period  57   d  is a required quantity (use record) of the component tabulated at a prescribed period such as every day, every week, or every month. 
   Furthermore, in the present embodiment, the history information generation program  80  carries out processing of calculating the difference between the previous component cross tabulation data file  56  and the current component cross tabulation data file  57 , and storing the difference in chronological order as a component requirement history data file  59 . 
   The component requirement history data file  59  comprises a sub-item  59   a , a parent item  59   b , a data creation date  59   c , a required quantity in each period  59   d  and a difference data  59   e.    
   The sub-item  59   a  is identification information given to the individual components. The parent item  59   b  is identification information of a subunit or the product apparatus using the component as a constituent. The data creation date  59   c  is the date when the difference calculation processing is executed. The required quantity in each period  59   d  is a required quantity (use record) of the component tabulated at a prescribed period such as every day, every week, or every month. The difference data  59   e  is a difference between the previous component cross tabulation data file  56  and the current component cross tabulation data file  57 , accumulated at a prescribed period such as every day, every week or every month. 
   On the other hand, the search server  20  consists of a computer system, and comprises the search program  21 . The search program comprises a function to receive a search request from the director server  30  and to reply with the search result. 
   The search program  21 , in addition, comprises a function to expand the component requirement history data file  59  converted into an XML file  60  in memory in the director server  30  as explained later, and to execute search processing that designates a particular component and period by a text search technique. The search program  21  comprises a function to set an appropriate threshold of the quantities in the fluctuation range of the required quantity of the component, and to automatically extract a component that has the required quantity fluctuation range exceeding the threshold (excess specifying logic) from the periodically recorded component requirement history data file  59 . 
   The director server  30  consists of a computer system, and software such as an XML creation tool  31 , a director  32 , an application server  33 , and a Web server  34  are implemented. 
   The XML creation tool  31  carries out processing to convert the component requirement history data file  59  obtained in the MRP server  10  into the XML file  60 . 
   The director  32  executes the exchange of the XML file  60  with the search server  20 , the management of search data, the management of the search server  20 , and the reception/response of the search request from an application via the application server  33  and the Web server  34 . 
   The application server  33  is server software comprising a function to receive a processing request from the search terminal  40  (a user of the production management system of the present embodiment) via the Web server  34 , and to work as a bridge to the processing of the director  32 . 
   The Web server  34 , by programs such as the search terminal control program  35 , performs processing to provide the search terminal  40  with the search services to be described later, and the processing includes processing of displaying an excess component search screen  90  on the search terminal  40 , receiving search conditions and relaying them to the application server  33  end, and processing of responding with the search result obtained from the search server  20  to the search terminal  40  via the director  32  and the application server  33 . 
   The search terminal  40  comprises a personal computer  41 , a display  42 , an input/output device  43 , and other elements. By accessing the Web server  34  of the director server  30  with a program such as a Web browser implemented in the personal computer  41 , search instructions of the component requirement history data file  59  converted into the XML file  60  are carried out and display of the search result on a display  42  and other operations are performed. 
   In the following description, an example of production management system operations of the present embodiments is set forth with reference to the flowcharts etc. of  FIG. 3A ,  FIG. 3B  and  FIG. 3C . 
   As for overall flow of the present production management system, first, the requirement data file  53  and the transaction data file  51  are generated by the MRP program  70 , the history information generation program  80  runs periodically, the current component cross tabulation data file  57  is generated from the requirement data file  53  and the transaction data file  51 , the component requirement history data file  59  is generated from the previous component cross tabulation data file  56  and the current component cross tabulation data file  57 , and the component requirement history data file  59  is handed over to the XML creation tool  31 . The XML creation tool  31  converts the received component requirement history data file  59  into an XML file, and accumulates the file in the search server  20 . The search terminal control program  35  displays information on the basis of the search instruction by a user from the search terminal  40 , or notifies an administrator of the information by means such as e-mail when an excess component is detected by the excess component specifying logic that is set in advance. 
   Details of the above flow are explained below. 
   First, at the instruction from a user, the MRP program  70  receives as input information called the “apparatus plan” such as the manufacturing deadline of a specific product apparatus and the quantity of manufactured product for every manufacturing deadline (step  101 ). On the basis of the “apparatus plan” of the specific product appratus, information such as an apparatus name  52   a , a subunit/component name  52   b , a basic unit  52   c , a component name  52   d , and a basic unit  52   e  of the apparatus configuration file  52  is registered in advance, the requirement data file  53  (BOM) recording information on procurement of a component (sub-item  53   a ) specified by the component name  52   d , date (required date  53   d ), and the quantity of product (required quantity  53   c ) is generated, and “component plan” on a component basis is prepared (step  102 ). 
   On the basis of the requirement data file  53 , information such as, for example, quantity of stock/product in process/inventory on order that is not shown in the drawing is set aside, component procurement is implemented by calculating the shortage, and the implementation result is recorded as the sub-item  51   a , the parent item  51   b , the quantity  51   c , the transaction content  51   d , and the transaction date  51   e  in the transaction data file  51  (step  103 ). 
   The history information generation program  80  performs data accumulation processing as shown in  FIG. 3B ,  FIG. 5A  and  FIG. 5B . Specifically, for each month, for example, the sub-item  53   a , the parent item  53   b , the required quantity  53   c  and the requested date  53   d  of the requirement data file  53  are compared with the sub-item  51   a , the parent item  51   b , and the quantity  51   c  of the transaction data file  51 , and cross tabulation is executed. The current component cross tabulation data file  57  including information of the sub-item  57   a , the parent item  57   b , the data creation date  57   c  and the required quantity in each period  57   d  is generated and stored ( FIG. 5A ) (step  201 ). 
   By comparing the previous component cross tabulation data file  56  generated in the previous cross tabulation processing with the current component cross tabulation data file  57  generated currently, the difference data of the required quantity of each component specified in the sub-item  57   a  (the required quantity in each period  57   d ) and that of the actual use record are calculated (step  202 ), and the result is recorded in the component requirement history data file  59  for each sub-item  59   a  by adding, in chronological order of, for example, the required quantity in each period  59   d , the current component cross tabulation data and the difference data  59   e  generated in step  202  ( FIG. 5B ) (step  203 ). The generated component requirement history data file  59  is sent to the XML creation tool of the director server  30  (step  204 ), and the current component cross tabulation data file  57  is stored as the previous component cross tabulation data file  56  (step  205 ). 
   The XML creation tool  31  of the director server  30  converts the component requirement history data file  59  shown in  FIG. 6A  as an example into the XML file  60  shown in  FIG. 6B  as an example (step  301 ), and accumulates the file in the search server  20  (step  302 ). 
     FIG. 4  shows a flow of the search terminal control program  35 . Upon being triggered by a prescribed trigger (step  404 ), by the excess specifying logic (step  406 ), the presence or absence of component excess inventory is determined (step  408 ). For the excess specifying logic in step  406 , the following rules (given as an example) may be set. 
   Rule 1: The components that exceed the needed quantity after setting aside a “component plan” within a previous specified period (e.g. n weeks, where n is a positive integer) are determined to be excess components. 
   Rule 2: Components for which the sum of the inventory estimation amount reaches a certain amount or more are determined to be excess components. 
   Rule 3: Compared with the previous “component plan”, components of the top n items (n is a positive integer) with a large reduction are determined to be excess components. 
   It is possible that by separately using or combining each of these rules 1-3, the excess specifying logic can be established, and the excess components can be specified. 
   When there are excess components, by searching the component requirement history data file  59  (XML file  60 ) accumulated in step  200  with the sub-item  59   a  of the excess component as a key, a history check of the “component plan” of the component is performed (step  410 ). 
   A parent apparatus (parent item  59   b ) that is the cause of the excess in the quantity of the components (sub-item  59   a ) and its “component plan” (requirement data file  53 ) are specified, and an administrator registered in advance is notified of the result by e-mail (shown in  FIG. 10  as an example); this is explained later (step  412 ). 
   Additionally, the search terminal control program  35  can execute the search by inputting the search conditions directly from the search terminal  40 . 
   Specifically, if a search is needed (step  402 ), the sub-item  59   a  and search range (threshold) etc. that a user intends to search for are input from the excess component search screen  90  shown in  FIG. 7 , and the search is executed (step  450 ). The search terminal control program  35 , then, searches for the component requirement history data file  59  (XML file  60 ) with the sub-item  59   a  of the excess components as a key. (step  410 ), and displays the applicable data (step  452 ). If the search range is defined by the search conditions, it is possible to highlight the applicable site (to enhance identifiability) by displaying using different colors, frames or shades. 
     FIGS. 7 ,  8 , and  9  are an example of a shift in the display screen of the display  42  showing tracing processes of the cause of the excess component (sub-item  59   a ) in the search terminal  40  operated by a user of the production management system of the present embodiment. 
   First, the excess component search screen  90  is displayed as shown in  FIG. 7 . 
   In the excess component search screen  90 , the search condition is to be input to the right, and by inputting the search conditions such as the name of the component, time period, and threshold, and by further designating button  91   c  of a search command tab  91  on the top as a result acquisition button, the search of information that fits the conditions from the XML files  60  registered in the search server  20  is started. As a result of the search, as shown in  FIG. 8 , a display field of the required quantity for each item  92  that calculates and displays a required quantity for each component and a display field of the required quantity for each item/parent item  93  that display a required quantity for each item/parent item are output in the excess component search screen  90 . 
   By a user of the production management system of the present embodiment designating a difference display button  91   b  of the search command tab  91 , as shown in  FIG. 9 , a display field of the difference for each item  94  and a display field of the difference for each item/parent item  95  are displayed on the excess component search screen  90 . 
   The display field of the difference for each item  94  is a field displaying a difference from the previous week calculated for each item. 
   The display field of the difference for each item/parent item  95  is a field displaying a difference from the previous week for each item/parent item. 
   The user can check the excess inventory by looking at these two screens. 
   It is also recognized that if the threshold of the reduction range from the previous week is set to be  40  in the search conditions, (−47) shown in the focused field  94  is found, and the sub-item  59   a  to be the excess inventory is a component “CA01022-0429” and the excess creation time (production date) is from 2005, Jan. 14 to Jan., 21. 
   By the user searching the display field of the difference for each item/parent item  95  on the basis of the sub-item  59   a  and the excess creation time, as shown in the focused field  95 , a production cutback (−44) of the parent unit of the parent item “PA2014-D03600LA” is found, and at the same time, as shown in the focused field  95 , a production cutback (−3) of another parent unit “PA02014-D03600LE” is recognized. 
   Note that in the example of  FIG. 9 , the identifiability of the user can be enhanced by displaying the rows that include focused information such as (−47), (−44) and (−3) in the above focused field  94  and focused field  95  in a frame. 
   When the display field of the requirement for each item/parent item  93  is considered on the basis of the information of the parent unit (parent item  59 b) and the excess creation time (production date), as shown in the focused field  93 , a production cutback (−44) from Jan., 14 to Jan., 21 of the parent unit “PA2014-D03600LA” is found, and similarly a production cutback (−3) from Jan., 14to Jan., 21 of the parent unit “PA02014-D03600LE” is found. 
   As described above, according to the present embodiment, if excess inventory is created in the components managed by a production management system such as MRP, a user of the production management system of the present embodiment, by designating the sub-item  59   a  of the component to the search terminal control program  35  and searching the component requirement history data file  59 , can promptly and accurately identify the time point when the component is procured, the production apparatus plan in which the component is procured, and the time point and the cutback or disappearance of products apparatus that caused the excess inventory. 
   As shown in  FIG. 11 , even in a case of many numbers of manufactured product apparatuses (e.g. a several thousand types), a case of many levels of the usage relation hierarchy between components (e.g. a maximum of 10 hierarchies), or a case of difficulty in specifying the cause of the excess components via conventional technology, according to the present embodiment, by accumulating every week (for example) the differences as the component requirement history data file  59  between the required quantity of components in accordance with the production plan and the actual use record by the history information generation program  80 , it is possible to accurately specify the cause of the excess of the component. 
   Specifically, in the example of  FIG. 11 , if a surplus of 100 of “component f” is found (event  501 ), a cutback history of the component f is searched with reference to the component requirement history data file  59  and the apparatus requirement history data file  58  by the search terminal control program  35  (event  502 ), pinpoint retrieval of the cutback history of “apparatus B” that corresponds to the subtraction amount of 100 of the component f can be achieved (event  503 ). 
   As a result, the user of the production management system of the present embodiment can prepare the component excess inventory control promptly and appropriately. Detailed verification of weekly MRP and component procurement and early detection of component excess (waste) can be achieved and significant improvement in management efficiency and management accuracy of the production management system by the existing MRP can be expected. 
   In other words, it is possible to appropriately manage the history of the excess inventory of components constituting a product. It is also possible to appropriately realize control of the component excess inventory generated in the production planning system. 
   It should be noted that the present invention is not limited to the configuration shown in the above embodiment, but various changes and modifications can be made within the scope of the gist of the present invention. 
   According to the present invention, it is possible to appropriately manage the history of the excess inventory of components constituting a product. 
   It is also possible to promptly and appropriately realize control of the excess inventory generated in the production planning system.