Basic principles of production planning in mrp systems. Material Requirements Planning (MRP) Material Requirements Planning. Mrp or material requirements planning

I continue to lay out definitions and requirements for systems.

4 MRP, CRP and MRP II concepts

4.1 Definition of MRP and MRP II. The history of development

The history of the development of this class of systems dates back to the 1950s, when the concept of MRP (Material Requirement Planning) was developed. But at that time, such systems were not widespread due to the lack of the necessary available computing resources. One of the ideologues of this class of systems was Joseph Orliski, who defined them as "Systems for planning material requirements, consisting of a number of logically related procedures, decision rules and requirements that translate the production schedule into a" chain of requirements ", synchronized in time, and planned" coverage »These requirements for each stock of components required to meet the production schedule. The MRP system will reschedule the sequence of requirements and coverage as a result of changes in either the production schedule, inventory structure, or product attributes. "

In 1975, Oliver Wight and George Plossl refined the MRP standard, defining its further development in MRP II. The main difference was that now planning took place not only taking into account the limitations on reserves and production capacity, but also on finance.

4.2 Input MRP II

The main input data in the MRP system:

Product data including BOM and routing

Demand data generated by MPS as well as data from sales and project management systems

Material supply data, including existing inventory, production order already placed, and planned purchase orders

As a result of the planning process, production orders (shop orders), purchase orders in the procurement system and exception messages are generated, which indicate that during the planning process there were problems that could not be resolved, or, conversely, when solving problems, it is necessary to change the already laid out plans.

The requirements planning process uses the item parameters discussed earlier (item type, order policy, order system, and order method) to determine whether the item should be ordered by the requirements planning function, in what quantity, under which order policy.

Typically, demand forecasting is part of the Volume Scheduling function that uses "item history" for statistical analysis and forecasting the movement of items in the market. If a specific business does not use the Volume Scheduling process, sales can be predicted for the MRP component based on sales budgets (that is, sales targets derived from any considerations). In some cases (spare parts, for example) sales can be predicted for an MRP component based on the sales budget, even if the demand forecasting process in the Volume Scheduling system is used for finished products. A typical example of such a situation is, for example, replacing one product within a product group with another (for example, a laser printer for a printer of another brand, or replacing a standard computer with a 500GB hard drive for 1TB.)

The demand for MRP components arising from commercial projections will be added to any existing demand for the same components derived from SQM or project management functions.

4.3 MRP II Processes

The MRP (II) system requirements planning function includes three processes:

Material Requirements Planning (MRP)

Capacity Requirement Planning (CRP)

Statistical Warehouse Management (SIC)

MRP II assumes the ability to automatically obtain information from the "corresponding" subsystems. That is why it is impossible to call a non-integrated system that implements MRP I, CRP, SIC and MPS workstations as a "class MRP II" system. Based on the analysis of the need for certain types of data and from the subsystems in which such data are usually generated, it is possible to compile a list of functional blocks that should constitute a software product that claims to be the "MRP II system". At the same time, it is probably wrong to call these blocks modules, since the latter term implies the possibility of an autonomous existence of each of them (each module). In this case, this is not always possible and, as a rule, impractical.

4.4 MRP II class software building blocks

The main blocks of MRP II class systems, as defined by APICS (American Production and Inventory Control Society), are:

Forecasting

Sales management

Volumetric scheduling - production planning

BOM and product structure management

Inventory Management

MRP - Material Requirements Planning

CRP - capacity planning

Workshop management (possibly - various modules for serial, custom, design or process production)

Finance and accounting

The financial analysis

The absence of any block in the software product means the impossibility (within the framework of correct marketing, of course) to characterize it as an MRP II system. However, this list does not say anything about the "depth" of elaboration of individual blocks. Accordingly, if a software product allows only one forecasting method (for example, averaging over historical data), or only one shop floor control unit (for example, only batch production), then such a product will still have the right to be called MRP II. Moreover, nothing can be said about the quality of the financial subsystem, or about the ability to maintain a certain type of warehouse management.

4.5 Main objectives of MRP

The main purpose of using MRP is:

Meeting the needs of production in materials, components and products for production planning and delivery to consumers;

Maintaining low inventory levels;

Planning of manufacturing operations, delivery schedules, purchasing operations.

The MRP system allows you to determine how much and in what time frame it is necessary to produce the final product. The system then determines the time and the required quantities of material resources to meet the needs of the production schedule.

The MRP process "explodes" the BOM of each item planned in the MPS down to the lowest level, additionally using the required lead times to estimate the time required to produce or purchase each item in the PTO, including components and assemblies. The Russian term "explosion" is associated with the name of the component of the structure of the finished product used in mechanical engineering, where this procedure was first applied: product - assemblies - components and materials. Thus, exploding is "going down" along the structure of product nodes to calculate the demand for raw materials and materials required for their production.

The demand for each low-level node (or semi-finished product) is summarized throughout the BOM (that is, if the same low-level product is contained in several BOM branches, then the total demand for all branches is calculated). The result is a material requirements plan (MRP) that shows the demand for each semi-finished product, subassembly, raw material, and material in each planning interval.

An essential condition for the effective operation of this process in MRP II systems is that, in addition to calculating the demand itself, the system distributes this demand in time, taking into account planned receipts and existing stocks, as a result, for each product, the time of launching it into production and / or the formation period is determined. order to the supplier in order to have time to satisfy the need at the right time. The execution logic and, accordingly, the need for raw materials and materials significantly depend on the established policy for the implementation of the planning process.

Terminology MRP

LLC - low-level-code; lowest level at which a component appears in a BOM

Item - any item of inventory, and sometimes a special BOM component

LT (lead time - delay time) - the time from the moment the order is issued to the receipt of the goods

Gross requirements (total need) - the need for a product (products) for the planning period (excluding available stocks, etc.)

Planned receipts

Products for which a production task has already been formed and the production date is known

Confirmed orders

Projected on hand - projected stock at the end of the period

Net requirements (net - "net" -requirement) - net-demand, determined after calculating the estimated availability

Planned order receipts - net requirement after conversion to production orders

Planned order releases - production order start times based on delay times

In addition to generating a planned production order and a planned purchase order, the MRP process can also generate exceptions for an existing production order or purchase order that might be needed when changes to the planned demand are made. For example, if the demand for some components in an existing production order or Purchase Order has changed, the MRP process will recommend replacing (changing) the quantity (amount) in the existing order to accommodate the additional (or reduced) demand. Recommended changes could include increasing, decreasing, eliminating, or reordering (by time or priority) scheduled orders.

The MRP process compares the total requirement for each item in each time period (or planning interval) with the expected receipt of the same item in the same time interval. The expected receipt is calculated by adding the planned quantity of products in production and the planned purchase at each time interval to the inventory at the beginning of the period. This expected receipt is based on "economic" inventory (the network actually uses the forecast for goods receipts), not just physical inventory.

If the total requirement for any item at any time interval exceeds the expected receipt, MRP uses a two-step process to establish compliance. The first step involves moving or augmenting (or both) existing production orders and purchase orders. If no orders (yet) exist, or existing orders cannot be changed, a new production order and purchase order will be scheduled to meet the (increased) demand.

If the demand for an item has decreased, MRP will first suggest reducing the quantity (amount) in an existing production order or purchase order, suggest holding orders, or canceling orders. Planned stock movements must be available for analytical work on any item, component, or assembly.

Typically, MRP requirements are generated by the Master Planning (MPS) function for components and assemblies whose requirements are forecast, and by the requirements planning function for components dependent on sales orders. In addition, sales forecasts can also be entered for MRP components.

4.6 Statistical Warehouse Management (SIC)

Although the demand for most raw materials, components, and assemblies in the assembly-to-order model is planned either by MPS or MRP, some demand for components or materials can be planned based on the SIC process. SIC components are usually cheap raw materials or assemblies that are used in many components of the finished product, such as hardware in a computer, or glue in furniture. These components are usually manufactured or purchased based on a "SIC Order Policy", a type of minimum inventory system.

The functions of warehouse stocks are usually considered as part of logistics, more often than as part of the production process, although in large industries the logistics and production components are often very closely related, especially their implementation in the function of in-house management. Regardless of how the warehouse function is defined in your business, its main tasks remain the same and boil down to statistical inventory control.

In principle, both purchased and produced item types can be assigned to the SIC ordering system. Whenever the "economic inventory level" of the SIC ordering system falls below the order point defined in the item master record, the SIC system plans to manufacture, or purchase, additional quantities of the item. In modern systems, it is possible to determine the safety stock for each warehouse separately, which makes it possible to implement independent management of replenishment of stocks in warehouses. The "Economic Inventory Level" is calculated by adding up the inventory available "on order" and the "available inventory" on hand ", and subtracting the reserved inventory.

The number of items that will be purchased or produced depends on the ordering method assigned to the item. SIC ordering system components are usually assigned one of three ordering methods:

Economic quantity (value) of the order

Fixed quantity (value) of the order

Replenishment to the maximum level of stocks

Typically in Russia, mixed ordering methods are used, in which the system prompts for the required quantity, and the purchasing department makes a decision "not below demand" or "close to demand". For an effective solution of this problem, the system should allow to quickly analyze the "sources" of the purchase order, which is implemented, for example, in the SyteLine system, but this possibility may not be available in the "standard systems".

SIC planned orders can be based on total inventory levels, or they can be generated separately for each warehouse. If the item type is manufactured, the SIC generation process results in a planned production order. If the item type is purchasable, the result is a planned Purchase Order. As with other planning types, the resulting planned production order and purchase order can be changed if desired or necessary.

If desired changes have been made to the planned SIC manufacturing orders and purchase order, the planned orders must be confirmed, then passed on to executive functions before they can be processed further. As with MRP planned orders, SIC planned orders can be confirmed manually or automatically and can be submitted manually or automatically. The generated SIC production order is passed to the shop floor management system, the generated SIC purchase order is passed to the purchasing system.

The warehouse module of an MRP system typically includes an extensive inventory analysis toolkit for the components of the SIC ordering system. Systems of this kind include sessions for ABC movement analysis, slow movement analysis, inventory valuation, etc.

4.7 Capacity Requirement Planning (CRP)

The CRP process involves calculating the temporarily-structured capacity requirement for each work center required to produce the components, assemblies, and finished goods that are planned in a material requirements plan (MRP). The process is similar to the MRP process, except that routing information for each item is used instead of the BOM. The CRP process only affects product breakdown components that are designated as manufactured and is not related to purchased components.

The CRP process calculates the required capacity using work center capacity, routing information, and the work center calendar to calculate available capacity. The capacity requirement is based on the planned production order generated by MPS, MRP and SIC. The CRP process also takes into account production orders that have been transferred to the shop floor but have not yet been completed.

In standard systems, the input data for planning the demand for production capacities are the data of the "planned start" MRP - that is, the generated demand for the produced assemblies and semi-finished products. Thus, it can only be realized after calculating the material requirements.

The result of the work is the so-called "load profile", which determines the required capacity to fulfill the plan for each work center.

If it turns out that the performance is insufficient to meet the MRP requirements, then either the MRP requirement must be changed, or the productivity must be increased. It may be possible to change the demand predicted by the MRP by starting production of some part of the product earlier than previously planned in order to use the reserve capacity at an earlier time interval. It may also be possible to increase productivity through overtime by adding extra shifts, subcontracting, etc.

CRP terminology

Load profile - load profile - compares the need with the planned (available) performance

Capacity - productivity - including loading and efficiency

Efficiency - efficiency - possible loading versus passport (not to be confused with loading)

Load percent - percentage of loading - ratio of loading to performance

If all the available performance enhancements are not sufficient to meet the MRP requirements, it may be necessary to reschedule the MPS. In the simplest business models of MRP systems, the productivity of work centers is usually considered unlimited and such problems do not arise, however, since real productivity is always limited, modern MRP systems provide the ability to perform planning in conditions of limited resources.

In the MRP system, the CRP function calculates the production capacity required to produce the planned production order generated by MPS, MRP, SIC.

MPS and MRP are used to generate a planned production order before the CRP process calculates the required capacity. The planned production order generated by these functions provides the basic input to the CRP process. If components are assigned to the SIC ordering system, a planned production order for replenishment (in-house semi-finished goods) must also be generated before starting CRP. Performance planning must be completed before a planned production order generated by MPS, MRP, and SIC can be released to shop floor management.

Another important function of the CRP is to analyze the financial implications of planned production. In addition to calculating the required capacity, the CRP process also performs a financial analysis of the deferred purchase and production order. Financial analysis in CRP uses information on purchasing, sales, stock, MPS, requirements planning.

The financial information analyzed by the CRP process includes available inventory, open purchase orders, open sales orders, open production orders, and planned (planned) orders. The financial analysis includes all planned movements (movements) of sales warehouse stocks, MPS, requirements planning, and planned requirements generated by the project management system.

Interaction with the financial subsystem.

After the MRP calculation, or SIC process, has been completed, a planned production or purchase order appears. In the "planned" state, orders do not affect the actual financial position of the company. Orders may still be changed (replaced), added and removed.

After confirming and converting the planned purchase order into a "real" purchase order, the company's financial position is expected to change as the debts to the supplier will increase from now on. Stocks will also increase (starting from the date of the expected delivery).

Based on the MRP or SIC calculation required to cover the planned costs, the working capital must be increased. This means, or "real" money, bank or commodity loans are needed to finance the purchase (increase) of inventory, work in progress and stock of finished goods. Depending on the financial condition and policy of the company, these types of components can be paid from the capital of the company or loans. Unpaid (up to some point) invoices or bank loans are also considered as a specific type of loans.

Financial links to MRP and SIC in the MRP system are indirect. The requirements planning process carries out financial transactions as a result of a planned acquisition or production order

4.8 Required MRP data

Main production schedule

The production schedule is formed under conditions of independent demand. The system does not contain any automation tools for drawing up a production schedule. The plan is formed by hand and must be realizable, that is, it must be consistent with demand and the financial plan. But at the same time, a list of key resources is drawn up for each unit of finished products. It reflects the scarcity of resources and the possible compensation for this deficiency. This tracking of resource requirements and comparing it with the available resources of the system must be carried out continuously. The production schedule itself also requires constant revision. To eliminate the lack of revision of plans, the production schedule is divided into periods. In the first period, modifications to the production plan are not allowed. In the second period, modifications are allowed, and it is necessary to coordinate the production plan with the available key resources. The further in time the period is from the present moment, the less definite and more dynamic the information becomes.

Specifications

BOM (Bill Of Material) is a list of components and materials required to manufacture a finished product, indicating the quantity and planned production or delivery time. Thus, the finished product is described down to materials and components.

Data on stock on hand and open orders

Based on the specifications, the total component requirements are calculated. These components should be ready by the time the "parent" node starts. The MRP algorithm processes the BOM in the same order in which the levels of the item composition tree follow, and based on the master production schedule, the total requirements for finished goods are calculated.

4.9 MRP Output

The output includes primary and secondary reports that serve a supporting function.

Planned orders - a schedule with a breakdown by planning periods, which contains the time and amount of the future order.

Permission to execute planned orders, i.e. materials are issued to production: the remainder of the stock is recalculated taking into account the costs of materials, and then the materials are transferred directly to production, i.e. production orders are issued.

A change in planned orders includes a change in the date or amount of an order, and cancellation of an order.

Plan control reports show deviations from plans, and also contain information necessary for calculating production costs.

Planning reports include existing supply contracts, purchase commitments, and other data that can be used to estimate future material requirements for production.

Exception reports highlight major inconsistencies and discovered errors in data and reporting.

The information for this article is taken from open sources, I do not claim authorship, I just tried to combine information from different sources into definitions that can be used to classify systems and find out if the system meets this class.

I hope you find this series of articles helpful.

I would be grateful for your comments.

course work

Introduction

The MRP-1 system is one of the most popular in the world, based on the logistics concept of "demand / resource planning". This system operates with materials, components, semi-finished products and their parts, the demand for which depends on the demand for a specific finished product.

The main goals of this system are to meet the need for material resources for planning production and delivery to consumers, maintaining a low level of inventories, work in progress, finished goods, planning production operations, delivery schedules, purchasing operations.

The main idea of MRP systems is that any accounting unit of materials or components required for the production of a product must be in stock at the right time and in the right quantity.

The need to plan the need for MR is due to the fact that the bulk of problems in the production process are associated with a delay or advance in the arrival of components, raw materials and materials, as a result of which, as a rule, in parallel with a decrease in production efficiency in warehouses, there is an excess (shortage) of materials received earlier. or later than the scheduled date. In order to prevent such problems, the MRP I (Material Requirements Planning) methodology was developed. Computer programs have been created that make it possible to optimally regulate the supply of MR, control stocks in the warehouse and the production technology itself.

The main task of MRP I is to ensure the availability of the required amount of required materials (components) at any time within the planning period, along with a possible reduction in current stocks, and therefore, unloading of warehouses.

One of the most popular logistics concepts in the world, on the basis of which a large number of micrologistic systems have been developed and operate, is the concept of "requirements / resource planning" (RP). The concept is often contrasted with the just-in-time logistics concept, meaning that push-type logistics systems are based on it.

Based on the established production schedule of the MRP I system, they implement a time-based - phase approach to establishing the value and regulating the level of stocks. Since this, in turn, generates the amount of required material resources for the production or assembly of a given volume of finished products, MRP I is a typical "push" type system, the enlarged diagram of which is shown.

MRP I as a "push" type system;

MR - material resources;

NP - work in progress;

GP - finished products

The basic micro-logistic systems based on the concept of "requirements / resource planning" in production and supply are the systems of "materials / manufacturing requirements / resource planning" (MRP I / MRP II), and in distribution - “distribution requirements / resource planning” (DRP I / DRP II) systems.

Practical applications typical of MRP I systems are available in the manufacturing process organization along with the procurement of material resources. According to the definition of the American researcher J. Orliski, one of the main developers of the MRP I system, the system of "material requirements planning (MRP system) in the narrow sense consists of a number of logically related procedures, decision rules and requirements that translate the production schedule into a" chain of requirements ", that are synchronized in time, as well as the planned coverage of these requirements for each stock of components required to meet the schedule ...

The MRP system will reschedule the sequence of requirements and coverage as a result of changes in either the production schedule, inventory structure, or product characteristics. ”

MRP systems handle materials, components, semi-finished products and their parts, the demand for which depends on the demand for a specific finished product. Although the logistics concept itself, which is the basis of the MRP I system, was formed quite a long time ago (from the mid-1950s), it was only with the advent of high-speed computers that it was possible to put it into practice. At the same time, the revolution in microprocessor and information technology has spurred the explosive growth of various applications of MRP systems in business. The main goals of MRP systems are:

Improving the efficiency of the quality of planning resource requirements;

Production process planning, delivery schedule, procurement;

Decrease in the level of inventories of material resources, work in progress and finished goods;

Improving inventory control;

Reducing logistics costs;

Meeting the need for materials, components and products.

MRP I made it possible to coordinate the plans and actions of the links of the logistics system in the supply, production and sales of the entire enterprise, taking into account the constant changes in reality. time scale ("on line"). It became possible to coordinate medium and long-term plans for supply, production and sales in MRP, as well as to carry out the current regulation and control of the use of inventories.

In the process of realizing these goals, the MRP system ensures the flow of planned quantities of material resources and stocks of products on the planning horizon. The system in MRP first determines how much and in what time frame the final product needs to be produced. The system then determines the time and the required quantities of material resources to complete the production schedule. A block diagram of the MRP I system is presented. It includes the following information:

Block diagram of the MRP I system

1. Consumer orders, forecast of demand for finished products, production schedule - MRP-I input.

2. Database of material resources - nomenclature and parameters of raw materials, semi-finished products, etc .; consumption rates of material resources per unit of output; the time of their delivery for manufacturing operations.

3. Database of stocks - the volume of production, insurance and other stocks of material resources in warehouses; correspondence of available stocks to the required quantity; suppliers; delivery parameters.

4. Software complex MRP-I - the required total amount of initial material resources, depending on demand; chain of requirements (needs) for material resources, taking into account the levels of stocks; orders for volumes of input material resources for production.

5. Output machine charts - a set of output documents: an order for material resources from suppliers, adjustments to the production schedule, schemes for the delivery of material resources, the state of the MRP-I system.

The input of the MRP-I system is consumer orders, supported by forecasts of demand for the company's finished products, which are included in the production schedule (schedules for the release of finished products). Thus, as with just-in-time micrologic systems, customer demand is a key factor in MRP-I.

MRP-I information support includes the following data:

Production plan for a specified item for a specific date;

Data on materials containing the specified names of the required parts, raw materials, assembly units, indicating their quantity per unit of finished product;

Data on stocks of material resources required for production, lead times, etc.

The material resources database contains all the required information about the range and basic parameters (characteristics) of raw materials, materials, components, semi-finished products, etc., required for the production (assembly) of finished products or parts thereof. In addition, it contains the rates of consumption of material resources per unit of output, as well as files of the times of delivery of the corresponding material resources to the production units of the company. The database also identifies links between individual inputs of production units in terms of consumed material resources and in relation to the final product. The inventory database informs the system and management personnel about the availability and size of production, insurance and other required inventories of material resources in the company's warehouse facilities, as well as about their proximity to the critical level and the need to replenish them. In addition, this database contains information about suppliers and delivery parameters of material resources.

2. Methodology MRP-1 (Material Requirements Planning)

In the 60s, through the efforts of the Americans Joseph Orlicky and Oliver Veit, a method for calculating the materials required for production was created, called MRP (Material Requirements Planning). Thanks to the dedicated work of the American Association for Inventory Management and Production (APICS), the MRP method has become widespread throughout the Western world, and in some countries (including Russia) it is even interpreted as a standard, although it is not.

One of the most popular logistics concepts in the world, on the basis of which a large number of micrologistic systems have been developed and operate, is needs / resource planning concepts(requirements / resource planning , RP). The RР concept is often opposed to the just-in-time logistics concept, meaning that push-type logistics systems are based on it (as opposed to the JIT approach).

Push (push) system is a production organization system in which parts, components and semi-finished products are transferred from the previous technological operation to the next one in accordance with a predetermined rigid production schedule.

Material resources and semi-finished products are "pushed" from one link of the production logistics system to another. In a similar way, finished products are “pushed” into the distribution network. A common drawback of the "push" system is insufficient tracking of demand with the mandatory creation of safety stocks. It is the presence of safety stocks that allows you to take into account changes in demand and prevent disruptions in production. As a result of the storage of stocks, the turnover of the company's working capital slows down, which increases the cost of production of finished products. Proponents of this concept, comparing it with the “Just in Time” concept, note the greater stability of the “push” system in the face of sharp fluctuations in demand and the unreliability of resource suppliers.

Based on the established production schedule, the MRP I systems implement a time-phase approach to setting the value and regulating the level of stocks. Since this, in turn, generates the amount of required material resources for the production or assembly of a given volume of finished products, MRP I is a typical "push" type system, the enlarged diagram of which is shown in Fig. 4.

The basic micro-logistic systems based on the concept of "requirements / resource planning" in production and supply are "materials / manufacturing requirements / resource planning" (MRP I / MRP II) systems, and in distribution (distribution) - systems, "distribution requirements / resource planning" (DRP I / DRP II).

Material flow

Order

Order fulfillment

Fig. 4. MRP I as a "push" type system;

MR - material resources; NP - work in progress; GP - finished products

The MRP I system was developed in the United States in the mid-1950s, but it became widespread both in the United States and in Europe only in the 1970s, which was associated, as already noted, with the development of computer technology. Micrologic systems like MRP I were developed around the same time period in the USSR and were initially widely used in the military-industrial complex. The usual practice of using MRP I systems in business is associated with planning and controlling procedures for ordering and supplying (purchasing) material resources, as a rule, of a wide range for industrial manufacturers of mechanical engineering products. Problems arising in the process of introducing the MRP I system relate to the development of information, software and mathematical support for calculations and the choice of a complex of computing and office equipment, that is, to those problems that are typical for ACS production and technological processes. The purpose of the implementation of MRP I is to improve the efficiency and quality of planning resource requirements, reduce the level of stocks of material resources and finished products, improve inventory control procedures and reduce the costs associated with these logistics functions.

MRP systems handle materials, components, semi-finished products and their parts, the demand for which depends on the demand for a specific finished product. Although the very logistics concept underlying the MRPI system , formed quite a long time ago (from the mid-1950s), but only with the advent of high-speed computers was it possible to put it into practice. At the same time, the revolution in microprocessor and information technology has spurred the explosive growth of various applications of MRP systems in business. The main objectives of MRP systems are:

Improving the efficiency of the quality of planning resource requirements;

Production process planning, delivery schedule, procurement;

Decrease in the level of inventories of material resources, work in progress and finished goods;

Improving inventory control;

Reducing logistics costs;

Meeting the need for materials, components and products.

MRP I made it possible to coordinate plans and actions of the logistics system links in supply, production and sales throughout the enterprise, taking into account constant changes in real time ("on line"). It became possible to coordinate medium and long-term plans for supply, production and sales in MRP, as well as to carry out the current regulation and control of the use of inventories.

In the process of realizing these goals, the MRP system ensures the flow of planned quantities of material resources and stocks of products on the planning horizon. System

MRP first determines how much and in what time frame it is necessary to produce the final product. The system then determines the time and the required quantities of material resources to complete the production schedule. Figure 5. the block diagram of the MRP I system is presented.

Rice. 5. Block diagram of the MRP I system

It includes the following information:

1. Consumer orders, forecast of demand for finished products, production schedule - input MRP I.

3. Stock database - the volume of production, insurance and other stocks of material resources in warehouses; correspondence of available stocks to the required quantity; suppliers; delivery parameters.

4.Program complex MRP I - the required total amount of initial material resources, depending on demand; chain of requirements (needs) for material resources, taking into account the levels of stocks; orders for volumes of input material resources for production.

5. Output machines - a set of output documents: an order for material resources from suppliers, adjustments to the production schedule, schemes for the delivery of material resources, the state of the MRP I system, etc.

The input of the MRP I system is consumer orders, supported by forecasts of demand for the company's finished products, which are included in the production schedule (schedules for the release of finished products). Thus, as with just-in-time micrologic systems, consumer demand is a key factor in MRP I.

MRP I information support includes the following data:

Production plan for a specified item for a specific date;

Data on materials containing the specified names of the required parts, raw materials, assembly units, indicating their quantity per unit of finished product;

Data on stocks of material resources required for production, lead times, etc.

The database on material resources contains all the required information about the nomenclature and basic parameters (characteristics) of raw materials, materials, components, semi-finished products, etc., required for the production (assembly) of finished products or parts thereof. In addition, it contains the rates of consumption of material resources per unit of output, as well as files of the times of delivery of the corresponding material resources to the production units of the company. The database also identifies links between individual inputs of production units in terms of consumed material resources and in relation to the final product. The inventory database informs the system and management personnel about the availability and size of production, insurance and other required inventories of material resources in the company's warehouse facilities, as well as about their proximity to the critical level and the need to replenish them. In addition, this database contains information about suppliers and delivery parameters of material resources.

The MRP I software package is based on systematized production schedules (schedules for the release of final products), depending on consumer demand and complex information obtained from databases on material resources and their stocks. The algorithms incorporated in the software modules of the system initially translate the demand for finished products into the required total amount of initial material resources. Then the programs calculate the chain of requirements for the initial material resources, semi-finished products, the volume of work in progress, based on information about the corresponding level of stocks, and place orders for the volumes of input material resources for the production (assembly) sections of the finished product. Orders depend on the specified by the nomenclature, the volume of requirements in material resources and the time of their delivery to the corresponding workplaces and warehouses.

After the completion of all the necessary calculations in the information and computer center of the company, the output complex of the MRPI machinegrams is formed , which is transferred in documentary form to production and logistics managers for making decisions on the organization of providing production sites and warehouse facilities of the company with the necessary material resources. A typical set of outputs of the MRP I system contains:

Requirements for material resources ordered from suppliers specified in terms of nomenclature, volume and time;

Changes to be made to the production schedule;

Delivery schemes of material resources, volume of supplies, etc .;

Canceled requirements for finished products, material resources;

MRP system status.

However, the preparation of primary data requires significant costs and accuracy. MRP I is typically used to plan ordering and procurement procedures for a wide range of materials, for example, for engineering companies. The following disadvantages of micrologistic systems based on the MRP approach can be identified:

A significant amount of calculations, preparation and preprocessing of a large amount of initial information, which increases the duration of the production period and the logistics cycle;

The increase in logistics costs for order processing and transportation when the firm strives to reduce the level of stocks or switch to the production of finished products in small volumes with high frequency;

Insensitivity to short-term changes in demand, since they are based on control and replenishment of stock levels at fixed points of order passage;

A significant number of failures in the system due to its large dimension and overload.

These disadvantages are superimposed on a common disadvantage inherent in all micro-logistic systems of the "push" type, which include the MRP1 systems. , namely: insufficiently strict tracking of demand with the obligatory presence of insurance stocks.

MRP I systems are mainly used when the demand for initial material resources is highly dependent on consumer demand for the final product. The MRP I system can work with a wide range of material resources (multi-assortment source material flows). While just-in-time advocates argue, and not without reason, that pulling micrologistic systems based on the principles of this concept respond more quickly and efficiently to changes in consumer demand, there are times when MRP I systems are more efficient. This is true for firms with long enough production cycles in the face of uncertain demand. At the same time, the use of MRP I systems allows firms to achieve the same goals as when using JIT technology, in particular, to achieve a reduction in the duration of the full logistics cycle and the elimination of excess inventory, if the time for making decisions on the management of production operations and the procurement of material resources is comparable to the frequency of changes in demand.

It implements the algorithm regulated by the MRP methodology and generates the results of the material aspect of production based on the input data.

The history of the emergence and development of MRP systems

In the pre-computer era, all tasks to control the availability of materials and components were performed manually by the personnel of the enterprise. For this purpose, warehouse accounting cards were used, which indicated information on the receipt and consumption of material. Such a system operated slowly, often failing as a result of inevitable errors and inaccuracies caused by human factors. As a result of its use, there were periods during which production was idle due to lack of material. At some enterprises, warehouse accounting cards are used to this day.

With the beginning of widespread automation in the sixties of the last century, programmers have found use of computer systems in planning the activities of an enterprise (in particular, production processes). The method they developed was called MRP and became widespread throughout the world. The main difference of the new methodology from the previous manual system was the orientation towards future needs and the neglect of data on consumption in the past. In fact, with the advent of MRP systems, orders for replenishment of warehouses began to form as needed and in the required volume.

At the end of the seventies of the last century, the capabilities of MRP systems were expanded due to the implementation of the idea of reproducing a closed loop. In particular, the following features have been added:

control of the conformity of the quantity of manufactured products to the quantity of products used;
preparation of regular reports on order delays, volumes and dynamics of sales and suppliers.

Further improvements to the system led to the transformation of the closed-loop MRP system into an extended modification, which was later called MRP II (Manufactory Resource Planning). This system was created for the effective planning of all (including financial and human) resources of a manufacturing enterprise.

Production planning systems are constantly evolving, trying to keep up with all the innovations in the production process.

The principle of operation of MRP systems

The material requirements planning system calculates the procurement plan for the required components and the production plan based on the BOM, the forecast demand and the technological nuances of production. The MRP system can also independently calculate due dates and production plans.

The cycle of work of an MRP system consists of the following stages:

determination of the optimal production schedule for the planned period based on the analysis of the adopted production program;
accounting for materials not included in the production program, but present in orders;
calculation of the total requirement for each material in accordance with the composition of the final product;
calculation of the net requirement for each material and preparation of orders for the material;
making adjustments to the generated orders in order to prevent untimely deliveries.

As a result, the system issues an order plan with operational changes and a number of service reports. The classic MRP system produces the following results:

Plan of Orders. It determines how much of each material must be ordered in each considered time period during the planning period. The order plan is a guide for further work with suppliers and, in particular, determines the production program for the internal production of components, if any.
Changes to the order plan. They are modifications to previously planned orders. A number of orders can be canceled, changed or delayed, as well as postponed to another period.

In principle, the MRP system can supply the user with other additional results, which are presented in the form of reports. The most indicative may be:

Forecast report. Information for analysis and long-term planning.
Executive report. Indicator of the correctness of all operations. Here the user can track whether all instructions were followed correctly, whether there was a failure in the system.
Delay report. Data on the most problematic orders, the execution time of certain functions and other points that may further affect the efficiency of work.

Capacity planning

In the MRP system, one can distinguish such a component as the Capacity Requirements Planning (CRP) subsystem. The CRP module is used to check a trial production program, created based on forecasts of demand for products, for the possibility of its implementation using the available production resources.

If the production program withstands the cycle of the CRP-module, then it begins to interact with the MRP-system, otherwise the program is adjusted, and it is re-tested by means of the production capacity planning subsystem.

Introduction

The new economic situation poses a number of challenges for enterprises that were not previously considered by them. Among the most important tasks facing industrial enterprises in modern conditions, one can single out:

increased competition,
the requirement to produce products in accordance with the current orders of buyers, and not with long-term long-term plans,
the need for prompt decision-making in a difficult economic situation,
strengthening ties between suppliers, manufacturers and buyers.

In the competition, only the one who reacts faster to business changes and makes better decisions wins the competition. It is information technology that helps industrial leaders in solving these complex problems. Market economy countries have extensive experience in the creation and development of information technologies for industrial enterprises. One of the most common methods of production and distribution management in the world is the MRP II (Manufacturing Resourse Planning) standard, developed in the United States and supported by the American Production and Inventory Control Society (APICS). APICS regularly publishes the document "MRP II Standard System", which describes the basic requirements for information production systems. The latest edition of this industrial standards system came out in 1989.

MRP II is a set of tried and tested sound management and control principles, models and procedures that serve to improve the performance of an enterprise. The idea behind MRP II is based on a few simple principles, such as dividing demand into dependent and independent. MRP II Standart System contains a description of 16 groups of system functions:

Sales and Operation Planning
Demand Management.
Master Production Scheduling
Material Requirement Planning
Bill of Materials.
Inventory Transaction Subsystem
Scheduled Receipts Subsystem
Shop Flow Control
Capacity Requirement Planning.
Input / output control.
Purchasing (Logistics).
Distribution Resourse Planning
Tooling Planning and Control
Financial Planning (Financial Management).
Simulation
Performance Measurement.

With the accumulation of experience in modeling production and non-production operations, these concepts are constantly being refined, gradually covering more and more functions.

In its development, the MRP II standard went through several stages of development:

60-70 years - planning the requirements for materials, based on data on stocks in the warehouse and the composition of products, (Material Requierment Planning)
70-80s - Cloosed Loop Material Requirment Planning, including the preparation of a production program and its control at the workshop level,
late 80-90s - based on data received from suppliers and consumers, forecasting, planning and production control,
90s - Planning distribution and resource requirements at the enterprise level - Enterprise Resourse Planning and Distributed Requirements Planning.

The task of information systems of the MRP II class is the optimal formation of the flow of materials (raw materials), semi-finished products (including those in production) and finished products. System of class MRP II - aims to integrate all the main processes implemented by the enterprise, such as procurement, stocks, production, sales and distribution, planning, control over the implementation of the plan, costs, finance, fixed assets, etc.

The MRP II standard divides the scope of individual functions (procedures) into two levels: required and optional. In order for the software to be classified as MRP II, it must perform a certain amount of necessary (basic) functions (procedures). Some software vendors have adopted a different range of implementations for the optional portion of the procedures in this standard.

Results of using integrated systems of the MRP II standard:

obtaining operational information about the current results of the enterprise, both as a whole, and with full details for individual orders, types of resources, implementation of plans;
long-term, operational and detailed planning of the enterprise's activities with the possibility of adjusting planned data based on operational information;
solving problems of optimization of production and material flows;
a real reduction in material resources in warehouses;
planning and control over the entire production cycle with the ability to influence it in order to achieve optimal efficiency in the use of production facilities, all types of resources and to meet the needs of customers;
automation of the work of the contract department with full control over payments, shipment of products and the timing of fulfillment of contractual obligations;
financial reflection of the enterprise as a whole;
significant reduction in non-production costs;
protection of investments made in information technology;
the possibility of a phased implementation of the system, taking into account the investment policy of a particular enterprise.

MRP II is based on a hierarchy of plans. The plans of the lower tiers depend on the plans of the higher tiers, i.e. the high-level plan provides inputs, targets and / or some kind of limiting framework for the low-level plans. In addition, these plans are linked in such a way that the results of the lower level plans have an opposite effect on the higher level plans.

If the results of a plan are unrealistic, then that plan or the top-level plans must be revised. Thus, it is possible to coordinate the supply and demand of resources at a certain level of planning and resources at the highest levels of planning.

STRATEGIC PLANNING

Strategic planning is long-term planning. It is usually drawn up for a period of one to five years. It is based on macroeconomic indicators such as economic trends, technology changes, market conditions and competition. Strategic planning usually applies to each year of the five-year plan and represents the planned indicators (goals) of the highest level.

BUSINESS PLANNING

A business plan is usually a yearly plan that is also drawn up on an annual basis. Sometimes it is revised several times throughout the year. It is usually the result of a management meeting that brings together sales, investment, fixed asset development and capital requirements and budgeting. This information is presented in monetary terms. The business plan defines targets for sales and production, as well as other lower-level plans.

PLANNING OF SALES AND PRODUCTION

If the business plan provides the summary data on sales volumes on a monthly basis (in monetary terms), then the sales and production volume plan breaks this information down into 10-15 assortment groups. The result is a production plan, which is revised monthly, taking into account the previous month's plan, actual results and data from the business plan.

A sales and production plan usually includes the following elements:

Volume of sales
Production
Stocks
Work in progress
Shipment

Of these elements, Sales Volume and Shipment are forecasts, since these are external data that cannot be directly controlled. The volume of production is planned, it is an internal indicator that is amenable to direct control. Inventory and WIP plans are controlled indirectly by manipulating sales forecasts, shipping forecasts and / or production targets.

Inventory and work-in-progress volumes are managed differently depending on the types of products a company makes or sells. The planned volume of stocks is an important factor, especially for those companies that produce products to the warehouse. The target volume of work in progress is an important factor for those companies that manufacture products to order.

The focus of sales and production planning is the production plan. Although it is called a production plan, it is, in principle, not just a production plan. It requires the availability of the required amount of resources throughout the company as a whole. If the marketing department is planning a jump in sales of a certain range of products, engineers must ensure that the required amount of equipment is available; the MTS department will have to provide additional supplies of materials (availability of new suppliers); the human resources department will have to ensure the availability of additional labor resources, as well as organize new work shifts. Plus, it will be necessary to ensure the availability of the required amount of capital (to pay for additional resources and reserves).

RESOURCE PLANNING

The production plan will be unrealistic if the availability of the required amount of resources is not ensured. Resource planning is a long-term planning that allows you to estimate the necessary (to fulfill the production plan) and the available amount of key resources, such as people, equipment, buildings and structures. If the need arises for the availability of the required amount of additional resources, it may be necessary to revise the business plan.

Resource planning only affects key resources and is prepared for the duration of the production plan (usually one year). A resource can be considered a key resource if its cost is high enough, or if its delivery time is long enough, or if other resources depend on it. Resources can be both external (suppliers' capabilities) and internal (equipment, storage space, money).

MAIN PRODUCTION SCHEDULE (PPGP)

The role of the head of the planning department is to translate the production plan into a specific production schedule. This plan - the PPGP - is a production plan superimposed on a timeline. PPGP shows what will be produced, when and in what volumes.

Because the production plan is expressed in such units as rubles, hours, tons, then in order to get the PPGP, it is necessary to take some steps to transform the production plan. The planned volume indicators for the assortment group must be converted into the planned volumes and dates for each product of this group separately. Depending on the type and volume of products manufactured, the GPGP can be divided into weekly, daily and even shift plans.

One of the main goals of the PWG is to provide a buffer: PWP distinguishes the forecasts and needs of the sales department from the MRP (material requirements planning). The philosophy is that forecasts and sales orders (sales orders) represent demand (or shipment), while PWG represents what will actually be produced in response to demand. In accordance with the PPGP, it is possible to manufacture products during a period when the demand for them is low, and vice versa. This can be the case in the manufacture of products for which demand is seasonal.

PPGP DEMAND

The head of the planning department must take into account all sources of independent demand. Independent demand is a demand that can be predicted, usually a demand for finished goods and parts. It is fundamentally different from dependent demand (demand that can be calculated based on data on the composition of the product). Sources of independent demand: production plan, projected shipment volume, sales orders (in production or assembly to order), demand for parts, inter-plant demand, and safety stock.

The main problem in the compilation of the PPGP is the determination of which products / components should be planned by the planning department, and which should be done automatically (by the MRP system). Planning items are items that must be planned under human supervision. Items planned by the MRP system, i.e. automatically, do not require this degree of control (they depend on the PWG). Determining how the planning of a particular type of product should be carried out depends on the types of products and technological processes. Usually a very small number of items need to be controlled by the planning department.

GENERAL CAPACITY PLANNING

Like resource planning, overall capacity planning is long-term and is based on key resources. This process uses PIP data rather than production plan data. So if PWP is expressed in volume and time characteristics, then general capacity planning is used to create a more detailed plan, which can be very useful in assessing the average needs of the company as a whole, as well as for assessing PWG.

MRP OR MATERIAL NEEDS PLANNING

Historically, MRP (Material Requirements Planning) was designed to control and replenish stocks. MRP II (Enterprise Resource Planning) expanded its use to planning capacity requirements, prioritizing and closing the entire planning chain.

MRP answers four basic questions:

What are we going to produce?
What do we need for this?
What do we already have?
What do we need to get more?

The GPGP answers the first question "What are we going to produce?" In order to achieve the goals set by the GPGP, all production and distribution activities are being planned. Because GPGP is a graph, it also answers questions such as "How much" and "When".

The second question is "What do we need for this?" essentially asks: "What products / components do we need to produce (or purchase) in order to fulfill the PIP plans?" To answer this question, we need to know two things: PPGP and the correct data on the composition of the product (product structure, product formula). PPGP and product composition data allow the system to determine what, how much, and when it will take in order to produce what we need.

The question "What do we already have?" can be divided into two questions: "What do we already have on hand?" and "What do we expect for orders?" On-hand stock in the warehouse is the answer to the first question, and the planned volume of receipts from production and from suppliers is the answer to the second question. Taken together, this data not only provides information about the stock on hand, but it also allows the system to estimate the expected stock. To answer the last question, you need to know the answers to the previous three. Taking what needs to be produced (gross needs), subtracting what is already there (in the warehouse and planned receipts), we find out what we need to receive in addition (net needs).

CRP OR CAPACITY NEEDS PLANNING

But the availability of the necessary amount of necessary materials does not mean anything without the availability of a sufficient amount of free working time. CRP (or Capacity Requirements Planning) is mid-level planning that uses data from MRP planned orders and manufacturing orders to determine the amount of work time required (both by labor and by technical).

Resource planning and overall capacity planning is the highest level planning used to plan resources such as physical equipment. CRP is more detailed planning. The load of workplaces is calculated on the basis of the technological route for the production of a product, which determines exactly how this type of product is produced. A technological route is similar to an instruction for use - a set of steps (or technical operations) that must be completed to make something. Each technical operation is performed at a certain workplace, which may consist of one or more people and / or equipment.

DRP OR DISTRIBUTION NEEDS PLANNING

When materials move from supplier to consumer, they move through the supply chain (or market channel). If you represent it graphically, then the supply chain represents the flows of supply and demand between suppliers and some divisions of the Customer's company, between these divisions and customers or between different divisions of the same company. DRP (Distribution Requirements Planning) coordinates demand, supply and resources between divisions of one or more companies.

A supply chain can have two or more levels of production and / or distribution units. These subdivisions can be in different dependence on each other; the important point is that one division can supply products to another division.

For example, a company produces goods on the territory of one division, and sells them from a separate sales warehouse.

Another company may have a central distribution center that supplies products to the warehouses of regional offices.

And the third example: the company has production facilities in two cities.

When planning the supply and demand of materials between departments, three main questions are answered:

What do we need to get (from other departments)?
What are we going to deliver (to other units)?
What can we supply?

While these questions are similar to those asked by MRP (Material Requirements Planning), there is one fundamental difference. In MRP, it is enough to know what and when supply and demand is expected. When there are several divisions, between which products are constantly moving, then DRP needs to know, plus to everything where (by which division) supply / demand arose.

The answer to the question "What do we need to get?" creates a demand for materials that need to be supplied from another department. DRP calculates all of these requirements in full (after starting MRP).

To the question "What are we going to put?" the answer comes from evaluating all sources of demand for a product, including sales orders, forecast shipments, parts requirements, safety stock, and inter-plant demand.

Supply and demand are monitored across departments using data from inter-plant requests and distribution orders. Based on the information about the department's needs for materials supplied by another department, DRP creates requests between these departments.

The answer to the last question "What can we supply" depends on the availability of materials (supply) and transport (resources). If demand (requirements) exceeds supply, DRP can be used to assign materials to several departments in a specified proportion.

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