JP2004127170A - Production plan creation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a totally optimum production plan creation method against the occurrence of irregularity such as discretely generated orders, an urgent order and production delay in a manufacturing industry. <P>SOLUTION: An adjustment function for adjusting a margin of time to spare added to a production plan in accordance with elapse of time is dynamically changed by being interlocked with fluctuations in a production plan creation system. Responses to the creation of a corrected production plan against fluctuations in the production plan, allocation of a new production plan and production delay are made and at the same time the influence on other production plan due to the responses is minimized by using the margin. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for creating a production plan in a manufacturing industry or the like.
[0002]
[Prior art]
Recently, many scheduling systems have been commercialized for the purpose of automatically creating a production plan, and at the same time, aiming for high operation of equipment and reduction of production lead time by reducing setup loss. In particular, at the present time when companies are required to introduce supply chain management (SCM), their importance as a core of a production management system is increasing more than ever.
[0003]
Although there are various types of scheduling systems, the basic idea is to allocate a production load to an optimal position (time) with respect to equipment capacity (operation time or man-hours), and a setup load associated therewith. Here, the optimal time means that the setup load on the production plan before and after is minimum, the delivery time can be strictly observed, the production lead time from the input process to the completion process is the shortest, and the equipment operation rate is 100%. It is determined by evaluation items such as approaching.
[0004]
This allocation is performed for a plurality of production requests for the surplus equipment capacity every day, every week, every two weeks, and so on at regular intervals. By collectively allocating, it is possible to create an overall optimum production plan using the facility capacity without waste.
[0005]
[Problems to be solved by the invention]
With the diversification of tastes in recent years, production of various kinds and small quantities, and enhancement of customer responsiveness, production of order-made products is rapidly progressing. Along with this, production planning is also changed from batch type processing that collectively allocates multiple production requests as in the past, when a production request occurs, it is allocated one by one, and based on the result, the delivery date is answered, and further, the conditions are changed and re-allocated. It is necessary to shift to interactive processing such as
[0006]
When a production request is allocated to production equipment one by one using the conventional method, the production plan is allocated to a gap in the production plan, so that the production capacity is not allocated, that is, the production plan is in a wormy state.
[0007]
In order to eliminate this worming, a method of periodically canceling the allocation for all production requests and performing the allocation again is conceivable. However, in the case of this method, since the previous allocation state is not considered, there is a high possibility that the allocation state largely fluctuates from the previous allocation state, and confusion at the production site such as a change in the setup at the production site or a change in the delivery date of the member is caused.
[0008]
Also, by allocating one by one, a production order that can be originally allocated by the delivery date has already been allocated at the time when the production order should be allocated, and a production plan that can meet the delivery date even after that time has already been allocated. The problem of not being able to do so occurs.
[0009]
Further, irregular measures such as interruption of an express order and recovery of a production delay by the conventional method, thereby impacting another production plan, for example, giving a new occurrence of a delivery delay. In this case, the measures are generally performed manually, and the merit of introducing the system is lost.
[0010]
As is clear from the above, it has been difficult with the conventional method to create an overall optimum production plan for discrete orders and irregular occurrences.
[0011]
The production plan creation method of the present invention is characterized by utilizing a margin added to a production plan. This concept of the margin was proposed in “Study on Interactive Scheduling Considering Uncertainty” published at Scheduling Symposium 2001 (held at Hokkaido University on October 10, 2001).
[0012]
The margin is assigned to an optimal position (time) in addition to the production load and the setup load related to the production plan before and after the production load when creating a production plan for a production order having product / quantity / delivery date information to be produced. It is an apparent load.
[0013]
By utilizing margins, it is possible to minimize the impact on production plans and maintain the overall optimization of production plans while responding to changes in production conditions such as production order changes / production progress / express orders. Is what makes it possible. By appropriately adjusting the margin according to the accuracy of the production order / the period from the current time to the actual production time, unnecessary load due to the margin can be reduced, and the degree of freedom of allocation can be improved. .
[0014]
[Means for Solving the Problems]
One of the present inventions is a method of allocating a production plan to a production facility, in which a margin is added over time in a production plan allocating method for adding a margin in addition to a facility occupation load required for production, and The adjustment method dynamically changes in conjunction with the fluctuation of the production planning system.
[0015]
The margin is preferably given an initial value when a production plan is allocated for the first time, and is preferably 0 when the production plan starts actual production. Therefore, it is necessary to adjust the value from the initial value toward 0 as appropriate. In the present invention, the adjustment method is not fixed, but is dynamically changed in conjunction with the fluctuation of the production plan creation system indicated by the past order fluctuation result / expedited order occurrence result, and the production plan is adjusted by optimizing the margin. The purpose is to flexibly cope with the fluctuation, that is, to improve the interactivity.
[0016]
Another one of the present invention is to use the margin in addition to the non-operating capacity existing in the production plan when creating a new production plan from the production order, the equipment capacity data, the product master and the production result data. This is a method of creating a new production plan while suppressing the effect on the existing production plan.
[0017]
Another one of the present invention is to use a margin and an equipment non-operating capacity given to an existing production plan when creating a modified production plan for a production delay. Since the production plan in which the delay has occurred is an execution plan, a margin is not generally given. Therefore, it is impossible to absorb the delay with its own margin. Therefore, all the production plans after the production plan in which the delay occurred have been shifted backward. However, a production plan that is shifted backward consumes margins associated with the production plan and minimizes the effect on subsequent production plans. By repeating this process, the effect of the production delay is minimized.
[0018]
According to another aspect of the present invention, even when a production order fluctuates in the increasing direction of the equipment occupancy load, a delay in delivery due to the fluctuation is avoided by using the margin and the equipment non-operation capacity added to the existing production plan. And minimizing the impact on production planning for other production orders. This means that if the increase of the equipment occupation load of the production order is less than the margin at that time, the increased load is absorbed by the margin. If the increase in equipment occupation load exceeds the current margin, the entire margin is used, and the excess shifts the production plan after the production plan of the changed production order backward. A production plan that is shifted backward consumes margins associated with the production plan and minimizes the impact on subsequent production plans. The above process is repeated until the immediately following production plan is not affected.
[0019]
Conversely, when the production order fluctuates in the decreasing direction of the equipment occupancy load, the margin is recalculated and an appropriate margin is given at the same time as reducing the equipment occupancy load. If a gap occurs between the end of the margin and the start of production of the next production plan due to this operation, that is, a new non-operating capacity is generated, the gap is eliminated by performing recalculation of the production plan that is periodically executed. I do.
[0020]
According to another aspect of the present invention, when a new production order is added, the degree of freedom of allocation is reduced, and when the production order is not allocated to the production equipment, the equipment capacity occupied by the margin is used. To create equipment non-operation capacity and allocate production orders to that part. However, when there is no facility capacity for allocating a production order with one margin, it is necessary to combine a plurality of margins or divide and allocate a production order.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 schematically shows an apparatus for creating a production plan according to the present invention. 1 is an input device for inputting various data, 2 is a storage device for constantly storing various data, 3 is a display device for displaying various data, 4 is a printing device for printing various data, 5 is the input device, and 5 is the input device. A central processing unit that comprehensively manages and controls devices, display devices, and printing devices and functions various methods, 6 is a production order including product information to be produced / delivery time / production start time / quantity / accuracy, and 7 is a production order. Equipment capacity data that records the holding capacity of equipment for which a plan is created, 8 is a product master including allocation conditions / switching time / standard man-hour or tact time to equipment, 9 is production actual data for a production order, 10 is a production plan, 11 is a program of a margin adjusting method according to the present invention, and 12 is a program of a production plan creating method according to the present invention.
[0022]
FIG. 2 schematically shows an allocation state of a production plan according to the present invention. Note that a production plan generally covers a plurality of processes, for example, a plurality of facilities existing in a process through press-welding-painting-assembly, but here, for convenience of explanation, one process in one process is performed. A description will be given by taking production allocation for equipment as an example.
[0023]
Each symbol in the figure is s_j: Production start time of production plan for production order j, e_j: Production end time of production plan for production order j, S_j: Production start time of production order j, E_j: Delivery date of production order j, L_j： Equipment occupancy load required for production according to production plan j for production order j, M_j: Equipment occupancy load of margin for production plan j, R_j: Non-operating capacity from the end of the margin for the production plan j to the production setup start time of the production plan for the production order j + 1, P_j: Equipment occupation load required for production setup of production plan j.
[0024]
In the conventional production schedule allocation method, this margin did not exist, and thus the non-operating capacity existed immediately after the equipment occupation load. On the other hand, in the present invention, a margin is also allocated at the stage of allocating a production plan to equipment, and the margin is used as a buffer for absorbing fluctuations over time and fluctuations of the production plan.
[0025]
FIG. 3 illustrates the flow of the process of recalculating the production plan, and the margin is adjusted in this series of processes. This series of processing is performed periodically for every production plan, for example, every hour to every day.
[0026]
First, the margin adjustment function will be described.
[0027]
The margin adjustment function is a function of the margin ratio r indicating the ratio of the margin to the production load as a function of the current time t.
r = K (t−O_j) + R₀+ C 1 formula
Is defined by O_j: Time at which the production plan is assigned to production plan j, r₀: Initial margin rate when a production plan is allocated, K: coefficient for a time term, C: margin rate at the time when the production plan actually starts production. When C = 0, the margin adjustment function for production order j is t = s_j, It is necessary that r = 0.
K = -r₀/ (S_j-O_j) ▲ 2 formula
That is,
r = (− r₀/ (S_j-O_j)) (T-O_j) + R₀+ C▲ 3 ▼ type
Becomes In equation (3), s_j, That is, a variable element such as the production start time of the production order j. The variable factors include, in addition to the production start time, a possible production start time / delivery time / quantity / remaining margin, etc., and the remaining processing capacity of each factory or equipment / production plan change occurrence frequency due to order fluctuation / There is the occurrence status of express orders. If the margin is not appropriately set in consideration of these variable factors, the interactivity due to the margin will be impaired. In other words, despite the production plan creation system where production plan changes frequently occur, the margin is small and cannot be dealt with. On the contrary, there is not much change, but a large margin is taken and it is kept until the start of production, so an operation loss occurs. Is considered as an example.
[0028]
It is difficult to incorporate the above-mentioned variable element into the equation (1) because the relationship between the variable element and the margin function cannot be uniquely determined.
[0029]
Therefore, in the present invention, reinforcement learning is used as an example of a method for determining K and C in Expression (1). Reinforcement learning is a method of obtaining a target solution by trial and error. FIG. 4 shows a flow of changing the margin adjustment function by the reinforcement learning. 13 is a process for stochastically changing K and C in the equation (1) from the previous values. When the evaluation is improved by a certain change, a change that inherits the tendency of the change is stochastically adopted. Reference numeral 14 denotes a process for evaluating the changed value, for example, using the delivery delay of each production order. Reference numeral 15 denotes a process for changing the selection establishment of K and C based on the evaluation result. This process is executed for a production plan for a certain period such as one day / one week / one month. The obtained result is applied to the next fixed period, and at the same time, K and C reinforcement learning are performed. Thus, the margin adjustment function always corresponds to the fluctuation of the production planning system.
[0030]
The margin adjustment processing is for calculating a margin with respect to the current time t using the margin adjustment function. The margin ratio is adjusted based on the calculation result, and a margin corresponding to the adjusted margin ratio is allocated to the equipment. The allocation of the margins to the facilities and the flow of the series of margin adjustment processes are as shown in FIG. If the corresponding production plan has begun or has been completed, the margin is set to 0 and the production results are cleared. When the production plan has not started production, the margin adjustment process is performed, the margin is updated, and the production load and the setup load are re-allocated to the production equipment together with the production load. As a result, if there is a gap in the production plan, that is, a non-operating capacity, the production plan is stuffed.
[0031]
In the process of reconciling the production result, for example, if the production result number: 20 is increased at the current time t with respect to the production plan of the quantity: 50, the production plan is reduced to 30.
[0032]
In the case of a production plan in which production is started or production is completed, a difference may occur between the expected number of actual productions at the current time t and the actual number of actual productions. If the expected number of actual productions ≦ the actual number of actual productions, the actual production is performed at a faster pace than the production plan, and in this case, the production plan after the production plan is not adversely affected. Conversely, if the expected number of actual productions> the actual number of actual productions, it means that actual production was performed at a slower pace than the production plan, which adversely affects the production plan after the production plan.
[0033]
Regarding the correction of the production plan for such a delay of the production plan, the above-mentioned adverse effect can be avoided by utilizing the margin.
[0034]
The margin added to the production plan during production depends on the margin adjustment function, but is generally zero. Therefore, it is impossible to absorb the delay of the production plan by the margin added to the production plan, and the subsequent production plan is shifted backward due to the delay.
[0035]
However, delay caused by production order m: d_mAnd the subsequent production order n
ΣM_x+ ΣR_{x + 1}≧ d_m(X = m... N-1) Equation (4)
Then delay: d_mIs not affected because it can be absorbed by the margin and non-operation capacity existing between the production plan in which the delay occurred and the next production plan.
[0036]
on the other hand,
ΣM_x+ ΣR_{x + 1}<D_m(X = m... N-1) Equation (5)
Will not be able to absorb the delay due to margin and non-operational capacity.
However,
d_m− (ΣM_x+ ΣR_{x + 1}) <E_m-E_m(X = m ... {n-1) formula (6)
Then, the margin between the production order delivery date and the production end time can absorb the delay that could not be absorbed by the margin and the non-operation capacity. Production orders that do not meet the above conditions will be delayed for delivery, and will need to be adjusted separately.
[0037]
With the above processing, the adjustment of the margin and the elimination of the production result with respect to the production plan are completed. Finally, the worm-eating state of the equipment capacity is eliminated by the stuffing process of the production plan. This worm-eating state was caused by adjusting the margin in the decreasing direction / actual production was performed at a slower pace than the production plan / capacity non-operating capacity occurred due to changes in production orders described later / production orders were deleted appear. Note that this production plan pre-filling process is the same as the conventional production plan creation method, and a description thereof will be omitted.
[0038]
Next, a method of using a margin to absorb fluctuations in the production planning system other than the production delay will be described.
[0039]
Factors that may affect the production planning system other than production delays include:
A) Changes in the production order already assigned
B) Adding a new production order
Can be considered. First, a description will be given of a method of utilizing a margin for “A) a change in a production order that is already allocated”. As a change in the production order, which affects other production plans in the production plan creation system, an increase in the quantity and a change in the production start time and the delivery date time are considered. When these changes occur, the production plan changes accordingly. If the change cannot be dealt with without deleting the current assignment and re-assigning it, the same action as in B) above is performed (described later). Here, a case where a change in a production order can be dealt with only by moving the production end time backward on the time axis with reference to the current allocation state will be described. Note that the action by moving the production end time forward on the time axis will not be described because it does not affect other production plans in the production plan creation system.
[0040]
By moving the production end time backward in the time axis, the production end time e_jIs e_j’. This increase,
Δe_j= E_j'-E_j▲ 7 ▼ type
Pay attention to. Note that the above-mentioned delay in the production plan: d_mTo this Δe_jWith the agreement, the delay of the production plan can be absorbed by the same method. (FIG. 6)
That is, the non-operation capacity until the next setup starts: R_{j + 1}≧ Δe_jThen, absorbing the increase in the non-operational capacity will not affect the subsequent production plan. R_{j + 1}<Δe_jIn the case of, the margin assigned to the production plan is used. That is, the load that could not be absorbed due to the non-operational capacity, Δe_j-R_{j + 1}To M_jTo absorb. Where Δe_j-R_{j + 1}> M_jIn the case of, the change cannot be absorbed even if the margin is used,
Δe_j-R_{j + 1}-M_jDelivery delay occurs. Also for subsequent production plans,
Δe_j-R_{j + 1}-M_jBack shift occurs. This shift is absorbed by the non-operating capacity and the margin given to the production plan of the production order j + 1 and thereafter. Although it depends on the margin function, the margin generally increases along the time axis. Therefore, this shift is likely to be completely absorbed in the margin of any production plan.
[0041]
When the delivery is delayed due to the continuous backward shifting, the backward shifting is completed. For a production plan in which the delivery date is delayed, processing such as lot division / delivery date change is generally performed to take measures to meet the delivery date. In this case, since the target production plan exists in the future from the present time, the degree of freedom for measures such as lot division / delivery date change is high, so that the influence on the entire production plan creation system can be suppressed.
[0042]
Next, a method of utilizing a margin for “B) adding a new production order” will be described. In addition, this includes the modification of the production plan in which the existing production plan is released and newly allocated.
[0043]
In order to add a production order, a non-operating capacity equal to or greater than the load of the production order is first searched from the time at which production can be started to the time of due date for the facilities to which the relevant production order can be allocated. If the search is successful, the addition is completed by allocating to the equipment. However, if the search fails, the allocation becomes impossible. Therefore, generally, processing such as lot division / delivery date change is performed, and the non-operation capacity is searched again. Therefore, since it is necessary to change the production order, for example, in the case of a lot division, the number of setups is increased, and in the case of a change in the delivery date, the customer is requested to change the delivery date. In order to avoid these adverse effects, attention is paid to the non-operating capacity and the margin between the production start possible time and the delivery date as allocation targets. A method of adding the production order n will be described with reference to FIG.
[0044]
1) Among the margins existing between the production start time and the delivery time, the margin M closest to the production start time, that is, the earliest margin in the time axis direction._kIs searched (state 1).
[0045]
2) Margin M_kCapacity R immediately after_{k + 1}And the equipment occupation load L of the production order n to be newly allocated_nAnd compare L_n≤M_k+ R_{k + 1}If
Margin M_kAnd release R_{k + 1}Used together with the production order n (state 2). At that time, R_{k + 1}Is used for allocation first, and L_n-R_{k + 1}Is allocated by consuming the margin.
[0046]
3) L_n> M_k+ R_{k + 1}Then, margin M_kCannot be dealt with simply by opening_{k + 1}Is further released (state 3). Where R_{k + 1}And M_{k + 1}Since the production plan for the production order k + 1 is allocated between them, a new production plan cannot be continuously allocated as it is. Therefore, L_{k + 1}And L_n− (M_k+ R_{k + 1}) Minute margin M_{k + 1}, Ie, L_{k + 1}To the rear of the time axis. By this operation, L_{k + 1}In front of, ie, R_{k + 1}Immediately after_n− (M_k+ R_{k + 1}) Occurs, and together with the existing surplus load, L_nTherefore, the production plan is allocated to the surplus load (state 4). However,
L_n− (M_k+ R_{k + 1})> M_{k + 1}Then, margin M_{k + 1}However, since it cannot be absorbed, the allocation of the production plan to the production order n fails. (In the above description, the setup load P_nIs not described, but L_nIt is necessary to process together. )
In the conventional production planning method without a margin, the delay in production is absorbed by (E_m-E_m) And R_xIn other words, there is a margin between the delivery date of the production order and the production end time, and the non-operating capacity limits the absorption of the delay. In the present invention, in addition to the above, the margin is used for delay absorption, and therefore, it is possible to absorb a production plan variation caused by a production delay more than the conventional method. FIGS. 7 and 8 show the flow of handling the addition of a new production order. In this case as well, the production end time of production order j is increased, and thus production delays and changes in production orders (production quantity) 6), the flow is almost the same as that in FIG.
[0047]
An example in which the above invention is applied to production planning in the DVD media business will be described below. In the DVD media business, after receiving an order from a movie company / game software company and receiving content data, the DVD media business is shipped to a designated shipping destination through a mastering-copying-label printing-packaging manufacturing process.
[0048]
The DVD media business has the following four features.
・ The market size has more than doubled every year, and many companies are entering the market.
・ Because it is a standardized product, the ability to respond to customers is a factor that determines the competitiveness of the business over other companies.
-There is a high possibility that order data changes and express orders will occur immediately before the delivery date.
・ Because of unstable productivity, there may be delays in planning.
[0049]
In the DVD media business, it is an essential condition of the business to respond promptly to fluctuating orders and production progress, and to completely comply with the specified delivery date. Hereinafter, examples of adapting the present invention to the DVD media business will be described.
[0050]
1) Preparation of recovery production plan for production delay
Due to a small stoppage of equipment or a change in yield, there may be a case where the result of the production plan is delayed. If there is a margin in the delivery date, the delay can be recovered within the margin, but there is almost no margin in the DVD media business. Therefore, if the production of a certain order is delayed by 100 sheets, the subsequent production plan is all delayed by 100 sheets, which causes a delivery delay.
[0051]
In the production plan creation method using the present invention, since a margin is given to each production plan, it is possible to suppress the occurrence of a lag-like delay due to the creation of the recovery plan using this margin. As for the delivery delay, the delivery delay can be eliminated by allocating production to a margin portion of another production line.
[0052]
2) Production plan revision for order change
Unlike general products, even if a customer receives a firm order, the order may fluctuate until just before the delivery date. As a variable factor, there is a high possibility of quantity and delivery date, and the influence on the production plan is large. In extreme cases, the quantity may change after production starts. In the case of a decrease in the number of units, it is possible to avoid the occurrence of operation loss by bringing forward the subsequent production, but in the case of an increase in the number of units, the same This delays the delivery time and causes the delivery deadline.
[0053]
In the production plan creation method using the present invention, since a margin is given to each production plan, the margin can be used to suppress the occurrence of a lag-like delay due to the modification of the production plan. With respect to the delivery delay, it is possible to eliminate the delivery delay by allocating production to a margin portion of another production line.
[0054]
3) Add production plan to express order
Although the lead time from order receipt to shipment is specified, there are also orders received at timings shorter than the lead time, that is, express orders. For example, if the prescribed lead time is 10 days, an order with a delivery date of December 20 can be rejected after December 11th. However, if rejected, there is a possibility that subsequent orders from the customer will flow to other companies, so there is a tendency to receive orders as much as possible. In that case, the method according to the invention works effectively for express orders.
[0055]
Further, in order to dynamically adjust the margin utilized in these inventions to an appropriate value, the margin adjustment method effectively functions. In the present embodiment, the Q-learning method was used as reinforcement learning for determining the coefficient of the margin adjustment function, and its effectiveness was verified.
[0056]
【The invention's effect】
According to the present invention, when a production plan fluctuates with respect to production equipment, a margin added to the equipment occupation time necessary for production, that is, a margin, is used to change the production plan, Even if a plan is allocated or a modified production plan is created for a production delay, the effect on other production plans can be minimized.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a production plan creation device according to an embodiment of the present invention.
FIG. 2 is a schematic diagram showing an allocation state of a production plan in one embodiment of the present invention.
FIG. 3 is a diagram showing a flow of a process of recalculating a production plan in one embodiment of the present invention.
FIG. 4 is a diagram illustrating a flow of a process of changing a margin adjustment function according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating a production order adding method according to an embodiment of the present invention.
FIG. 6 is a diagram showing a process flow corresponding to a production delay and a change in the production plan in the production plan creation method according to one embodiment of the present invention.
FIG. 7 is a diagram showing a flow of processing corresponding to addition of a new production order in the production plan creation method according to one embodiment of the present invention.
8 is a diagram showing the same processing flow as FIG. 7, and is connected to FIG. 7 by (1) and (2).
[Explanation of symbols]
L_jProduction load
P_jSetup load
M_jMargin
e_jProduction end time
E_jDelivery time
R_jNon-operating capacity

Claims (4)

In creating a production plan for a production order having at least one of product information to be produced, a delivery time, a quantity, and an accuracy, a production load based on the production plan and a setup load related to the preceding and following production plans are added on a time axis. A method of creating a production plan by allocating a margin serving as an apparent load, wherein the margin changes based on a change in a production plan creation system such as a past order change record and an express order record. Adjusting using a margin adjustment function to perform, the margin adjustment function is a step of changing the coefficient of the margin adjustment function from the previous value and calculating, and a step of comparing the calculation result with the previous value and evaluating the result, If the evaluation result improves, the step of selecting a coefficient value to maintain the improvement By return run Ri, production planning method characterized by correspond to fluctuations. The margin adjustment function for calculating the margin is a function of the margin ratio r indicating the ratio of the margin to the production load as a function r = K (t−O _j ) + r ₀ + C with respect to the current time t.
O _j : time at which the production plan is assigned to production order j, r ₀ : initial margin rate when assigned to the production plan, K: coefficient for the time term, C: margin at the time when the production plan actually starts production 2. The production plan creation method according to claim 1, wherein the production plan is defined by a rate. Calculating the initial value of the margin in the relevant production plan; allocating the margin, the production load and the setup load to the production equipment to create a production plan; and confirming whether or not the relevant production plan has started production. And if the result of the check indicates that the production has not yet started, the step of recalculating and updating the margin. If the production plan has already started production, the margin is set to 0 and the production results are deleted. Updating the production load, allocating the updated margin, the updated production load and the setup load to the production equipment, and, as a result, eliminating the gaps in the production plan and performing the justification process. The production plan creation method according to claim 1, wherein the production plan is created by executing the following. A case where the production plan is delayed, a case where the production order is changed in the increasing direction with respect to the production plan, a case where the production load and a new production order are added (only when there is no delivery delay to the subsequent plan). A production plan creation method for correcting a production plan when there is an increase in production load,
A first step of determining whether or not the production end time of the production order exceeds the due date of the production order;
If it exceeds, perform the second step to warn the delivery delay of the production order,
If not, the "increased production load A" and "the sum B of the margin for the relevant production plan and the non-operating capacity for the production plan immediately after this margin" are calculated.
The capacity for the increased production load is released in the order of the non-operating capacity from the margin, and the increased production load is assigned to the released capacity. Conversely, when A> B, the difference between A and B is determined. Only the third step of shifting the relevant production plan backwards,
"The sum B of the margin for the relevant production plan and the non-operating capacity for the production plan immediately after this margin" and the fourth step of allocating the increased production load to the non-operating capacity generated by moving the production plan backward. Have
2. The production according to claim 1, wherein the first to fourth steps are repeated until either the production end time exceeds the delivery time and / or there is no production plan behind the production plan. Planning method.

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