Determination of material requirements in tables. Determining the need for material resources
A specified period of time within which a given number of items must be produced. In the Kanban system (see [K 13]), a day is usually taken as a time cycle. In the MCI system (see [M 126]) is a week. When planning the requirements for materials at the end of each planned production period (or time cycle), a comparison of planned output volumes with actual ones must be carried out. If discrepancies are found as a result of such a comparison, then measures are taken to correct the situation.
In the statement of work to be performed during repairs, a description is given repair work by type, calculation of the need for materials for repair and the cost of repair work, indicate the time of transfer of equipment for repair and responsible executors. Attached to the statement is a detailed application for necessary materials, fittings and spare parts , as well as schemes and working drawings approved by the chief engineer . Stopping technological installations at the re-
Further, just because the manager is aware of the existence of a problem, it does not follow at all that the true problem has been identified. The leader must be able to distinguish symptoms from causes. Consider, for example, a pharmaceutical company that receives many complaints from pharmacies due to delays in fulfilling their orders. The real problem, as it turns out, is not this delay. An examination of the issue showed that orders were being delayed due to production difficulties at the firm's three chemical plants. This was caused by a shortage of initial chemicals and spare parts for equipment, which in turn was due to poor forecasting of the need for materials and spare parts.
Material requirements planning
Freight turnover is calculated on the basis of the production program and the norms of the need for materials and fuel in an enlarged nomenclature. From the production program is determined
XVI.1. Material and stock planning
If the enterprise carries out capital construction in an economic way, then the need for materials for it is calculated separately.
Based on the calculations of the need for materials and the size of the necessary stocks for all types of raw materials, materials, semi-finished products (from outside), containers, as well as for auxiliary materials, balance sheets are drawn up to determine their quantity to be procured in the planning period, and sources of receipt.
The insurance, or guarantee, stock is intended to cover the need for materials when current stocks are exhausted in the event of any changes in the conditions of supply or consumption (late receipt of materials, overfulfillment of the production plan).
Formation of the real content of the module - group norms a. This group should contain standards for the need for materials, equipment, semi-finished products, etc., and standards for the use of both these resources and the production capabilities of the module, which are determined when developing the module design based on the nominal value of the target return. The need for resources can be reflected either by a specification or by fixed standards (the ratio of the need for a resource of each type to the nominal value of the target return). The standards of use are a function of the value of the target output of the module (following) within the limits of its stability of operation - regulation (Fig. 17).
When planning and designing objects from standard blocks, it is necessary to take into account the need for materials, products and the cost of work associated with their installation on site.
In conditions of uneven production, the average annual rate should be calculated as a group rate, finding the weighted average by the volume of products (works). The average annual individual norms serve as the basis for determining group consumption rates, which are used in the aggregated calculations of the forecasted need for materials at the level of associations of sub-sectors and the ministry as a whole. During current planning and for a five-year period, group consumption rates are calculated on the basis of individual rates by type of product and the corresponding production volumes as a weighted average value according to the well-known formula
It is customary to calculate the total savings from the implementation of measures as the difference between the requirements for materials for the planning period, determined according to the norms of the planning and base year, or through indicators (coefficients) of replacement or savings, and the volume of implementation of measures.
The annual need for materials by groups (subgroups) of labor tools is calculated depending on the data of individual norms using one of the formulas.
The specified list of standard indicators is intended for current and long-term planning of the need for material resources for construction needs at the appropriate levels of production management. It is unlawful to use industry (sub-sectoral) standards for planning the need for materials for specific industries and enterprises. Under these conditions, individual norms, differentiated by individual elements of the object, must be applied. Thus, in the gas industry, individual and group consumption rates of materials rely on the construction of typical installations.
Indicators of the need for materials (rolled ferrous metals and steel pipes) are determined according to the specifications for the working drawings, taking into account the additional cost of waste and losses by coefficients (Table 12).
The amount of losses from unreasonable determination of the need for materials in the absence of consumption rates is determined by the expression
When calculating the need for materials, other areas of consumption can be taken into account not only with the help of aggregated norms, but also by introducing correction factors into the calculation. The values of these coefficients are determined by a quantitative assessment of the volume of consumption of materials in the development of a list of standards.
For research and development work, the need for materials is calculated according to average consumption rates per 1 thousand rubles. estimated cost of these works.
In addition to raw materials, reagents and catalysts in the main production and basic materials in some auxiliary productions, the enterprise needs a very extensive range of materials, the need for which is not related to the functional dependence on the volume of production. These are the so-called auxiliary materials for general production purposes, replaceable parts of equipment, Construction Materials, overalls, metals, electrical products, etc. ., To calculate the need for materials in this group, the consumption rate per unit of raw materials or products is not suitable. Therefore, other natural or conditional meters are accepted. For example, the consumption of lubricating oils is normalized per hour of operation of a machine of a certain size, electric lamps - per unit area of \u200b\u200ba workshop or installation, overalls - per worker,
Since 1982, all construction projects included in the state capital construction plan of the Minneftegazstroy have been transferred to a comprehensive supply of materials through territorial bodies logistics . In this regard, the design documentation should contain data on the need for materials, structures and details.
The planning block includes the tasks of optimal planning of capital investments, transportation of construction materials, tasks of operational planning, tasks of calculating the need for materials and
Types of requirements for materials. The need for raw materials and materials is understood as their quantity required by a certain date for a set period to ensure the fulfillment of a given production program or existing orders.
The need for materials for a certain period is called the periodic requirement. It consists of primary and secondary.
Primary refers to the need for finished products, assemblies and parts intended for sale, as well as purchased spare parts. Calculation of the primary need is carried out using the methods of mathematical statistics and forecasting, giving the expected need. The risk of an incorrect assessment or an inaccurate forecast of needs is offset by a corresponding increase in safety stocks.
The primary need is the basis of management material flows at enterprises operating in the field of trade. For industrial enterprises the primary need should be decomposed into secondary components, such as components, parts and raw materials.
Example 1
The furniture factory produces work tables for completing kitchen furniture. The sink is located in the table, which in turn is completed with a mixer for cold and hot water.
The need for a sink and faucets is called secondary, since it can be determined from the primary need (number of work tables). If sinks and faucets are supplied in trading network as necessary spare parts, then there is both a primary and a secondary need for these products.
When calculating dependent requirements, the following are assumed to be specified: primary requirement, including information on volumes and terms; specifications or applicability information; possible additional deliveries; the amount of materials at the disposal of the enterprise. Therefore, deterministic calculation methods are used to determine dependent requirements. If this method of establishing the need is not possible due to the lack of specifications or the insignificant need for materials, then it is predicted using data on the consumption of raw materials and materials.
The need for production supporting materials and wearing tool is called tertiary. It can be determined on the basis of the secondary on the basis of indicators of the use of materials (deterministic determination of demand), by carrying out stochastic calculations based on the consumption of available materials or by an expert.
Under gross requirement is understood as the need for materials for the planning period, regardless of whether their stocks are in stock or in production. Respectively net - need characterizes the need for materials for the planning period, taking into account their available stocks and is obtained as the difference between the gross - the need and the available warehouse stocks by a certain date.
Example 2
Let one of the items of materials have both primary and secondary requirements. In this case, it could be assembly units, which are used as components in the manufacture of a product (secondary requirement), and are supplied to the market in the form of spare parts (primary requirement). Table 1 shows that gross demand is determined from primary and secondary requirements. There are 450 units in stock. material. Net requirement is 650 units. (1100 - 450). To determine the net need for a certain period, a volume is subtracted from the warehouse stocks every time, not exceeding what is necessary to satisfy it. So, by periods: period 1 - net - there is no demand, since stocks exceed gross demand; period 2 - net - there is no demand, stocks at the beginning of the period are 210 units. (450 - 240); period 3 - the amount of cash on hand is 50 units. (210 - 160) and net - demand - 170 units. (220 - 50).
Table 1
Calculation of gross - and net - requirements
In practice, the total need for materials increases relative to the gross indication for the additional need due to defects in production and work on maintenance and equipment repair. After comparison with the amount of available stocks, the residual requirement is adjusted by the amount of current stocks.
Methods for determining needs.Necessary condition effective management material flows is the knowledge of needs for the future. The following methods can be used to determine it:
Deterministic calculation in accordance with the production plan and available specifications for manufactured products;
Forecasting needs by extrapolating data on the use of materials for the future using methods of mathematical statistics;
Subjective assessment based on expert opinions.
Deterministic Methods are used to calculate the dependent requirements for materials with known primacy. With the analytical approach, the calculation proceeds from the product (its specification) along the hierarchy levels from top to bottom. The synthetic method involves calculations for each group of parts based on the degree of their applicability at individual levels of the hierarchy.
The stochastic calculation method allows you to set the expected demand based on forecast estimates based on data from the past period. For this purpose, the approximation of average values, the method of exponential smoothing and regression analysis are used.
Average Approximation used in environments where material demand fluctuates from month to month with a steady average.
Forecasting by this method is a procedure of averaging the past values of material requirements. In this case, the weight of each of the demand values can be the same (simple average calculation method) or different if fresh data has a greater weight (moving average calculation method).
Exponential smoothing method used in the case when forecasting the process of changing the need for material resources is made on the basis of the levels of a series of dynamics, the weights of which decrease as the level is expected from the moment of the forecast. For this circuit, a constant smoothing coefficient a is introduced into the calculations, the value of which is chosen in such a way as to minimize the forecast error.
The forecast equation, taking into account exponential smoothing, is written in following form:
yt+1 = ayt + a(1-a)yt-1 + a(1-a)2yt-2 + … + a(1-a)kyt-k + … + (1-a)ty0,
where y0 is a value that characterizes some initial conditions
Regression analysis involves the approximation of known trends, the consumption of material resources using mathematical functions that can be extrapolated to the future period. In accordance with the nature of the dependence, linear and non-linear regression analysis are distinguished. The method of linear regression is advisable to apply with a conditionally proportional increase in consumption. If the demand curve is not approximated by a straight line, then a non-linear regression analysis is applied.
Methods of material support. Order method. Material support based on planned targets.
Purchasing logistics- this is the process of providing an enterprise with material resources for production, placing it in warehouses, storing and issuing it to production if necessary.
Purchasing logistics aims to be as efficient as possible while meeting the needs of production in material resources for production.
Tasks purchasing logistics: 1) determining the required volume, assortment and the most efficient mode of supplying material resources to production from warehouses, as well as regulating the maximum allowable prices for resources for the purchase and delivery, minimizing procurement costs;
2) choosing the most suitable suppliers and agreeing with them all the terms of the supply contract, concluding a supply contract, monitoring the quality of the raw materials left and the timing;
3) compliance with the deadlines for issuing new orders for the supply of raw materials and materials;
4) ensuring control between demand and supply, matching the size of orders and terms to the needs of production, optimal loading of warehouses, no downtime due to non-delivery of raw materials, minimizing the cost of spoilage of raw materials through stock control;
5) compliance with and control over the quality of the supplied raw materials (when concluding a supply contract, it is necessary to specify the level of quality and standards);
6) providing each workplace with the necessary production resources- resource-providing on the ground;
7) control economic characteristics procurement process and search for new ways to reduce procurement costs and improve the quality of production service, new suppliers, new solutions for optimizing procurement operations.
There are several types of need for material resources.
primary need- the need for finished products, parts, assemblies of parts, spare parts, components intended for sale.
secondary need- this is the need for component parts, parts, assemblies intended for the production of finished products.
Tertiary need- the need for auxiliary materials and wearing tools designed to service the main production of products.
Depending on the stock of materials available in the warehouse, there are:
1) net need- this is the need for materials for personal needs, taking into account the available stocks in the warehouse;
2) gross requirement- the need for materials for the planned period, excluding the available stock in the warehouse of the enterprise.
The process of acquiring materials can be divided into several stages:
1) drawing up requests (they should contain information about how much material needs to be supplied, what types of materials, the delivery time and who is responsible for drawing up the request. An application for the need for materials is compiled some time before the materials run out of stock in order to the supplier managed to complete the order before the production stops due to lack of resources.);
2) analysis of applications;
3) selection of suppliers (a very important stage in the process of purchasing materials, because each supplier provides a different list of services and responsibilities for the supplied goods, different quality, level of service, price, etc. With the right choice of suppliers, an optimal ratio of price and the quality of the supplied material.);
4) placing an order;
5) control over the fulfillment of the order (includes quality control of the supplied material, timing, fulfillment of all clauses of the supply contract).
The main purpose of material requirements planning is to ensure that the required quantity of required materials is available at any given time within the planning period. With the help of requirements planning, it is ensured that the volumes of materials needed for both internal use and sales are purchased or produced on time. The planning process includes the continuous control of stocks and, in particular, automatic creation draft purchase orders and production orders.
Planning requires all information on stocks of materials, including reserved, in order to calculate the volume of purchases or production.
Drawing up a volume-calendar production plan
When drawing up a volume-calendar plan, sales are planned for the future by means of a sales forecast. Volumetric - calendar plan created using planned independent requirements. Planned independent requirement (i.e. demand for the finished product, assemblies, hot goods and parts) uses this information to create a minimum stock level for material requirements planning.
Formation of input information for the MRP system
The input information for MRP consists of three main parts:
Description of the state of materials
- Production program
- List of components of the final product.
- Descriptions of the state of materials
The description of the state of the material is the main input to the automated MRP system. This part contains a description of the state of materials: what materials are in orders, in production, their volumes, prices, stocks.
Production program
A production program is a schedule for allocating time to produce a given quantity of end product in a planned period or range of periods. This input element is created as a result of the analysis of the Production Schedule.
List of components of the final product
The list of components of the final product is information containing lists of materials-constituents for all final products. This input element contains a list of all raw materials, components and their constituent parts that are included in the final product. The list of components also includes the quantity of each component required to produce one unit of the final product and its structure (how the constituent materials are connected).
Material requirements planning (MRP) basic steps
The main steps of the MRP system are:
- Planning the release of the final product
- Planning of orders for components
- Calculation of total demand
- Net requirement calculation
- Maintenance of previously planned orders
Planning for the release of the final product
This step determines the quantity and release date of the final product needed in each time period.
Parts order planning
At this step, components (components) not included in the production program, but present in orders, are included in planning as a separate item. Thus, for them it is created new need in the material.
Calculation of the total requirement for materials
At this step, the production program data for components is broken down into total requirements for all materials for the planned a period of time, in accordance with the list (specifications) of materials-components for the final product.
Calculation of Net Material Requirements
In this step, the total material requirement is transferred to the quantity of materials on hand and in orders for each period, according to the description of the state of the materials. The net requirement for each material is calculated as follows:
(Net Need)= (Total requirement)- (Materials on hand) - (Safety stock) - (Reservation for other purposes)
If the net requirement is greater than zero, an order is created for the material.
Maintenance of previously planned orders
Orders placed in periods prior to the planned are taken into account for subsequent periods at each step of the production process.
The results of the MRP system
The main output elements of the MRP(MRP) system are:
- Plan of orders
- Changes to previously planned orders
Also, additional output elements of the MRP system are:
- Planning bottleneck report
- Performance report
- Forecast report
- Main results
The main output elements of the MRP system are:
- Plan of orders
- Changes to previously planned orders
Order plan
The order plan determines how much of each material is to be ordered in each time period. This output is used as guidance when creating internal production orders, as well as when purchasing material from external vendors.
Changes to previously planned orders
This output element determines which changes should affect previously planned orders. The number of orders may change, some orders may be canceled or suspended.
Additional results
Additional output elements of the MRP system are:
Planning bottleneck report
- Executive report
- Forecast report
Planning bottleneck report
The Exceptions report identifies individual bottlenecks in the planning program that require additional attention and possibly intervention to ensure the correct amount of material is available in each planned time period. Such "bottlenecks" can be:
Late Orders
- Consumable balances
- Errors in system reports
- Performance report
The performance report is necessary to monitor the correct operation of the MRP system, to timely eliminate its failures. An example of the elements of a performance report would be warnings about a change or decrease in the available stock of materials down to zero.
Forecast Report
This report is used for long term planning production. An example of this report could be production forecasts for the future, reports on material purchases, clarification of demand sources, etc.
Material order types
Material orders are divided into two main types:
Production order
- Purchase order
- Production order
Order fulfillment for materials produced in-house is controlled by a production order. A production order contains its own scheduling methods, including scheduling production capacity and accounting for production costs.
Purchase order
Materials purchased from external vendors initiate the purchasing process.
.
The requirement for materials for a certain period is called the periodic requirement. It consists of primary, secondary and tertiary.
Primary refers to the need for finished products, assemblies and parts intended for sale, as well as for purchased spare parts. Calculation of the primary need is carried out using the methods of mathematical statistics and forecasting, giving the expected need. The risk of an incorrect assessment or an inaccurate forecast of needs is compensated by a corresponding increase in safety stock.
The primary need is the basis of material flow management in enterprises operating in the field of trade. For industrial enterprises, the primary need should be decomposed into secondary components.
The secondary is understood as the need for component parts, parts and raw materials necessary for the production of finished products.
Example 4
The furniture factory produces work tables for completing kitchen furniture. The sink is located in the table, which, in turn, is completed with a mixer of cold and hot water.
The need for a sink and faucets is called secondary, since it can be determined from the primary need (number of work tables). If sinks and faucets are supplied to the distribution network as necessary spare parts, then there is both a primary and a secondary need for these products.
When calculating dependent requirements, the following are assumed to be specified: primary requirement, including information on volumes and terms; specifications or applicability information; possible additional deliveries; the amount of materials at the disposal of the enterprise. Therefore, deterministic calculation methods are used to determine dependent requirements. If this method of establishing the need is not possible due to the lack of specifications or insignificant need for materials, then it is predicted using data on the consumption of raw materials and materials.
Tertiary refers to the production need for auxiliary materials and wearing tools. It can be determined on the basis of the secondary on the basis of indicators of the use of materials (deterministic determination of demand), by performing stochastic calculations based on the consumption of available materials or by expert means.
Depending on the accounting of available stocks, gross and net requirements for materials are distinguished.
Under gross requirements is understood as the need for materials for the planning period, excluding stocks in the warehouse or in production. Accordingly, under net needs the need for materials for the planning period is understood, taking into account available stocks. It is defined as the difference between the gross demand and the inventory on hand by a certain date.
Example 5
Let one of the items of materials have both primary and secondary requirements. In this case, we can talk about assembly units that are used as components in the manufacture of a product (secondary requirement), and are supplied to the market in the form of spare parts (primary requirement). From Table. 2 shows that the gross requirement is determined from primary and secondary requirements. There are 450 units in stock. material. The net requirement is 650 units. (1100 - 450). To determine the net need for a certain period, a volume is subtracted from the warehouse stocks every time, not exceeding what is necessary to satisfy it. So, by periods: period 1 - there is no net demand, since stocks exceed gross demand; period 2 - there is no net demand, stocks at the beginning of the period are 210 units. (450 -- 240); period 3 - the amount of cash on hand is 50 units. (210 - 160) and net demand - 170 units. (220 - 50).
table 2
CALCULATION OF GROSS AND NET REQUIREMENTS FOR SPARE PARTS (UNITS)
In practice, the total need for materials increases relative to the gross indicator by an additional need due to defects in production and maintenance and repair of equipment. After comparison with the amount of available stocks, the residual requirement is adjusted by the amount of current stocks.
Ratio various kinds requirements for materials is shown in fig. 2.
Rice. 2. The ratio of different types of material needs
A necessary condition for the effective management of material flows is knowledge of the needs for the future. The following methods can be used to determine it:
Deterministic methods of calculation in accordance with the production plan and available specifications for manufactured products;
Stochastic calculation methods;
The classification of the listed methods is shown in fig. 3.
Rice. 3. Classification of methods for determining needs
Deterministic calculation methods are used to calculate the secondary requirements for materials with a known primary. With the analytical method, the calculation proceeds from the product (its specification) along the hierarchy levels from top to bottom. The synthetic method involves calculations for each group of parts based on the degree of their applicability at individual levels of the hierarchy.
Stochastic calculation methods allow you to set the expected demand based on numerical data characterizing its changes over a certain period of time. For this purpose, the approximation of average values, the method of exponential smoothing and regression analysis are used.
used in environments where material demand fluctuates from month to month with a steady average.
Forecasting by this method is a procedure of averaging the known values of the demand for materials.
are used in the case when the forecasting of the process of changing the need for material resources is based on the levels of a series of dynamics, the weights of which decrease as the given level moves away from the moment of the forecast. For this purpose, a constant smoothing coefficient a is introduced into the calculations, the value of which is chosen in such a way as to minimize the forecast error.
The forecast equation, taking into account exponential smoothing, is written in the following form:
where y 0 is a value that characterizes some initial conditions.
Regression analysis involves the approximation of known trends in the consumption of material resources using mathematical functions that can be extrapolated to the future period. In accordance with the nature of the dependence, linear and non-linear regression analysis are distinguished. The method of linear regression is advisable to apply with a conditionally proportional increase in consumption. If the demand curve is not approximated by a straight line, then a non-linear regression analysis is applied.
Types of requirements for materials. Methods for determining needs
The need for raw materials and materials is understood as their quantity required by a certain date for a set period to ensure the fulfillment of a given production program or existing orders.
Example 1
Under gross requirement net - need
Example 2
Let one of the items of materials have both primary and secondary requirements. In this case, we can talk about assembly units that are used as components in the manufacture of a product (secondary requirement), and are supplied to the market in the form of spare parts (primary requirement). Table 1 shows that gross demand is determined from primary and secondary requirements. There are 450 units in stock. material. Net requirement is 650 units. (1100 - 450). To determine the net need for a certain period, a volume is subtracted from the warehouse stocks every time, not exceeding what is necessary to satisfy it. So, by periods: period 1 - net - there is no demand, since stocks exceed gross demand; period 2 - net - there is no demand, stocks at the beginning of the period are 210 units. (450 - 240); period 3 - the amount of cash on hand is 50 units. (210 - 160) and net - demand - 170 units. (220 - 50).
Table 1
Methods for determining needs.
Deterministic calculation in accordance with the production plan and available specifications for manufactured products;
Forecasting needs by extrapolating data on the use of materials for the future using methods of mathematical statistics;
Subjective assessment based on expert opinions.
Deterministic Methods
Average Approximation
Exponential smoothing method are used in the case when the forecasting of the process of changing the need for material resources is made on the basis of the levels of a series of dynamics, the weights of which decrease as the given level is expected from the moment of the forecast. For this circuit, a constant smoothing coefficient a is introduced into the calculations, the value of which is chosen in such a way as to minimize the forecast error.
yt+1 = ayt + a(1-a)yt-1 + a(1-a)2yt-2 + … + a(1-a)kyt-k + … + (1-a)ty0,
where y0 is a value that characterizes some initial conditions
Regression analysis
Methods of material support. Order method. Material support based on planned targets.
1. Tasks and functions of procurement logistics.
2. The process of acquiring materials and its main stages.
3. Determining the need for materials.
4. Providing production with materials.
5. Methods for calculating supplies.
1
The concept of procurement logistics
Purchasing logistics functions
Increasing role of purchasing logistics
AT modern conditions
. Tasks and functions of procurement logistics
The concept of procurement logistics. Procurement logistics is the process of providing enterprises with material resources, placing resources in the warehouses of the enterprise, storing them and issuing them to production.
The purpose of procurement logistics is to meet the production needs for materials with the highest possible cost efficiency.
This goal is achieved by solving a number of tasks that can be grouped as follows:
Maintaining reasonable terms for the purchase of raw materials, materials and components.
Ensuring an exact match between the amount of supplies and the need for them.
Compliance with production requirements for the quantity of raw materials and components.
Purchasing logistics functions. Procurement logistics performs the following functions:
formation of a strategy for the acquisition of material resources and forecasting the need for them;
receiving proposals from suppliers and evaluation of received proposals;
selection of suppliers;
determination of the needs for material resources and calculation of the quantity of ordered materials and products;
agreeing on the price of ordered resources and concluding supply contracts;
control over the delivery of materials;
output quality control of material resources and their placement in the warehouse;
bringing material resources to production units;
maintenance of stocks of material resources in warehouses at the normative level.
The growing role of procurement logistics in modern conditions. Transition to market economy determines the role and growing importance of procurement logistics in social production.
Market conditions have given rise to a series of significant changes in the field of material and technical support of production. Among them, the most important were:
the pressure of a rapidly growing diversity in the range of products demanded by the market;
reduction of time of implementation in production new products, accelerating the expansion of the range;
reduction of the duration of the production cycle;
aggravation of competition between producers against the backdrop of accumulation of the market with the necessary goods.
As a result of scientific research carried out in the 70-80s and the implementation of practical actions to improve the system of material support for production, the concept of procurement logistics was formulated, corresponding to the conditions for the functioning of the spheres of material production and the circulation of goods in market conditions.
^
2. The process of purchasing materials and its main stages
Drafting applications
Application analysis
Supplier selection
Placement of applications
Order fulfillment control
Completion of the acquisition process
^ Purchasing process includes a number of specific, logically interrelated types of work. The following stages of the process of acquiring materials are distinguished: preparation of applications, analysis of applications, selection of suppliers, placement of orders, analysis of orders, fulfillment of orders.
Drafting applications. Applications for the purchase of materials are prepared by the relevant employees of the functional divisions of the enterprise. They contain information about what types and quantities of materials the company needs, when they should be received and who made the request.
Applications are drawn up in such a way that the quantities of materials expected to be received outstrip the actual requirements for them.
The time between the placement of applications and the receipt of materials on them is called the lead time. It plays an important role in the procurement and inventory management process. Early bidding reduces the negative impact of unexpected delays in deliveries.
At the same time, an excessive increase in lead time leads to an increase in inventories. Employees responsible for compiling requisitions should set the delivery dates of materials with a minimum lead, taking into account the capabilities of the supplier and the needs of the consumer of materials.
Application analysis. Applications for the consumption of materials are analyzed in the logistics service with the participation of specialists from other departments. The purpose of the analysis is to ensure minimum costs for each type of material, specific consumer properties which are intended to be used in production. Research methods are functional cost analysis and cost construction.
During the analysis, answers should be obtained to next questions. Can cheaper materials meet the needs of production? Are these needs justified? Is it possible to refuse them? Can other types of materials meet the identified needs? Is it possible to simplify the design of manufactured products? Is the supplier able to reduce the price of materials by participating with the consumer in the development of the product or by analyzing the received specifications?
The supply service itself does not have the right to replace the materials specified in the applications. Department employees must analyze incoming requests and offer such options for the purchase of materials that can lead to a decrease in the cost of orders.
Indeed, the logistics service knows the offers of suppliers and competitive prices. Through the joint efforts of the employees of this service, the design and technology departments, and production, technical and economic solutions can be found that will lead to the improvement of designs and manufacturing technology of products based on the use of cheaper and better materials.
Choice of suppliers. When choosing suppliers, the main criteria are: the reliability of the supplier, its ability to supply the necessary resources of proper quality and on time, the supply of material resources at the lowest possible prices, the remoteness of the supplier from the consumer, the supplier's free capacity, etc.
The main sources of obtaining information about suppliers and materials are personal contacts with "sellers"; advertisements placed in advertising publications; description of goods that are given in catalogs and prospectuses; visiting enterprises and studying the practice of supplying products; information received from banks, trade associations, public institutions etc.
As a result of studying all these sources, a list of trusted suppliers is compiled. At the same time, the quality of the supplied materials and the services provided, the price level, compliance with the delivery time are taken into account.
After that, it remains to establish contacts with suppliers, receive proposals from them on prices and delivery times, and select those who offer the most profitable terms. It is advisable to distribute large orders between two or more suppliers in order to check the competitiveness of the main supplier to protect themselves from possible surprises.
Placement of orders. The acquisition of materials is carried out by different methods, depending on the type of materials and components. The main procurement methods are:
purchase of goods in one large batch at a time;
regular purchases of materials and products in small batches, when the buyer orders the required amount of goods that are delivered to him in batches over a certain period;
daily (monthly) purchases. The method is used where cheap and quickly used goods are purchased;
receiving goods as needed;
purchase of goods with immediate return. These are exceptional cases where it is not possible to obtain them as needed.
Basic elements of a contract.
1. Offer and acceptance of the offer.
A contract is drawn up if one party offers a certain batch of goods under a certain chain and on different conditions, and the other party accepts this offer.
2. Financial conditions.
A contract must have a value, that is, it becomes a contract in the legal sense only when financial terms are stipulated in it.
3. The right to enter into contracts.
Only certain officials(director, CEO) authorized by the enterprise and acting on its behalf.
4. Legality.
The contract must be legal, that is, fully comply with the legal norms of the country.
The structure of the contract provides for the definition of the subject of the contract, an indication of the quality and quantity of goods, the amount of the contract, the procedure for the delivery and acceptance of goods, the responsibilities of the parties, the procedure for resolving disputes.
Order fulfillment control. The size of the orders and the duration of the period during which these orders are fulfilled are controlled by the Procurement Department. At the same time, it is possible to adjust the schedules for the supply of materials and the corresponding refinement of schedules for the release of products.
Completion of the acquisition process. Receipt of ordered materials in specified quantities and on acceptable terms is a necessary sign of completion of the transaction. Purchase and sale are properly documented.
Product acceptance is important. During the acceptance process, you must make sure that the goods have been received:
the required quality;
in the right amount;
from your supplier;
at the appointed time;
for the agreed price.
^ 3. Determining the need for materials
Types of material requirements
Methods for determining needs
Types of requirements for materials. The need for raw materials and materials is understood as their quantity required by a certain date for a set period to ensure the fulfillment of a given production program or existing orders.
The need for materials for a certain period is called the periodic requirement. It consists of primary and secondary.
Primary refers to the need for finished products, assemblies and parts intended for sale, as well as purchased spare parts. Calculation of the primary need is carried out using the methods of mathematical statistics and forecasting, giving the expected need. The risk of an incorrect assessment or an inaccurate forecast of needs is offset by a corresponding increase in safety stocks.
The primary need is the basis of material flow management in enterprises operating in the field of trade. For industrial enterprises, the primary need should be decomposed into secondary components, such as components, parts and raw materials.
The furniture factory produces work tables for completing kitchen furniture. The sink is located in the table, which in turn is completed with a mixer for cold and hot water.
The need for a sink and faucets is called secondary, since it can be determined from the primary need (number of work tables). If sinks and faucets are supplied to the distribution network as necessary spare parts, then there is both a primary and a secondary need for these products.
When calculating dependent requirements, the following are assumed to be specified: primary requirement, including information on volumes and terms; specifications or applicability information; possible additional deliveries; the amount of materials at the disposal of the enterprise. Therefore, deterministic calculation methods are used to determine dependent requirements. If this method of establishing the need is not possible due to the lack of specifications or the insignificant need for materials, then it is predicted using data on the consumption of raw materials and materials.
The production need for auxiliary materials and wearing tools is called tertiary. It can be determined on the basis of the secondary on the basis of indicators of the use of materials (deterministic determination of demand), by carrying out stochastic calculations based on the consumption of available materials or by an expert.
The ratio of primary, secondary and tertiary needs is shown in fig. .
^ Types of needs
in raw materials
need for dependency need for dependency
on the nature of the executed from accounting for cash on hand
material functions
Primary
Secondary
Tertiary
Gross Net-
need need need needneed need
in materials, in materials, in auxiliary - Primary, Gross-
determined for production ma- Secondary, demand
market value of products, materials Tertiary minus
I make up demand - the needs of cash
primary to planned stock
required period
ness
Rice. . Types of material requirements
Under gross requirement is understood as the need for materials for the planning period, regardless of whether their stocks are in stock or in production. Respectively net - need characterizes the need for materials for the planning period, taking into account their available stocks and is obtained as the difference between the gross - the need and the available warehouse stocks by a certain date.
Let one of the items of materials have both primary and secondary requirements. In this case, we can talk about assembly units that are used as components in the manufacture of a product (secondary requirement), and are supplied to the market in the form of spare parts (primary requirement). From Table. it can be seen that the gross requirement is determined from primary and secondary requirements. There are 450 units in stock. material. Net requirement is 650 units. (1100 - 450). To determine the net need for a certain period, a volume is subtracted from the warehouse stocks every time, not exceeding what is necessary to satisfy it. So, by periods: period 1 - net - there is no demand, since stocks exceed gross demand; period 2 - net - there is no demand, stocks at the beginning of the period are 210 units. (450 - 240); period 3 - the amount of cash on hand is 50 units. (210 - 160) and net - demand - 170 units. (220 - 50).
table 2
Calculation of gross - and net - requirements
| View needs | Need by segments planning period | Total Need |
|||||
| 1 | 2 | 3 | 4 | 5 | 6 | in spare parts |
|
| 1. Primary need for spare parts | |||||||
| 2. Secondary need | 160 | 120 | 180 | 90 | 120 | 160 | 830 |
| 3. Gross requirement | 240 | 160 | 220 | 120 | 160 | 200 | 1100 |
| 4. On hand | 450 | 210 | 50 | 0 | 0 | 0 | 450 |
| 5. Net need | - | - | 170 | 120 | 160 | 200 | 650 |
In practice, the total requirement for materials increases relative to the gross indication for the additional requirement due to defects in production and maintenance and repair of equipment. After comparison with the amount of available stocks, the residual requirement is adjusted by the amount of current stocks.
Methods for determining needs. A necessary condition for the effective management of material flows is knowledge of the needs for the future. The following methods can be used to determine it:
deterministic calculation in accordance with the production plan and available specifications for manufactured products;
forecasting needs by extrapolating data on the use of materials for the future using methods of mathematical statistics;
subjective assessment based on expert opinions.
Methods of determination
needs
Deterministic Stochastic Subjective
calculation calculation estimate
^
Analytical Synthetic Score by Score
method analogy method by intuition
Method
Exponential Approximation Regression
mean-value smoothing analysis
^
Rice. . Methods for determining the need
Deterministic Methods are used to calculate the dependent requirements for materials with known primacy. With the analytical approach, the calculation proceeds from the product (its specification) along the hierarchy levels from top to bottom. The synthetic method involves calculations for each group of parts based on the degree of their applicability at individual levels of the hierarchy.
The stochastic calculation method allows you to set the expected demand based on forecast estimates based on data from the past period. For this purpose, the approximation of average values, the method of exponential smoothing and regression analysis are used.
^ Average Approximation used in environments where material demand fluctuates from month to month with a steady average.
Forecasting by this method is a procedure of averaging the past values of material requirements. In this case, the weight of each of the demand values can be the same (simple average calculation method) or different if fresh data has a greater weight (moving average calculation method).
^ Exponential smoothing method are used in the case when the forecasting of the process of changing the need for material resources is made on the basis of the levels of a series of dynamics, the weights of which decrease as the given level is expected from the moment of the forecast. For this circuit, a constant smoothing factor is introduced into the calculations, the value of which is chosen in such a way as to minimize the forecast error.
The forecast equation, taking into account exponential smoothing, is written in the following form:
y t+1 = y t + (1-)y t-1 + (1-) 2 y t-2 + … + (1-) k y t-k + … + (1-) t y 0 ,
where y 0 is a value that characterizes some initial conditions
^
Regression analysis
involves the approximation of known trends, the consumption of material resources using mathematical functions that can be extrapolated to the future period. In accordance with the nature of the dependence, linear and non-linear regression analysis are distinguished. The method of linear regression is advisable to apply with a conditionally proportional increase in consumption. If the demand curve is not approximated by a straight line, then a non-linear regression analysis is applied.
^
4. Providing production with materials
Methods of material support
Custom Method
Planned assignments
Material support based on
Carried out consumption
Methods of material support. In the practice of enterprises, several methods of planning the material support of production are used (Fig.):
ostentatious;
based on planned targets;
based on actual needs.
material methods
production support
Order-based Based on implementation-
planned targets for consumption
Orders by Method Method
Singular to several timely rhythmic
orders to items of orders of orders
Rice. . Methods of material support for production
ostentatious method assumes that the required material is purchased only when a requirement arises, so no stock is created. This method of material support of production is used in the conditions of a single and small-scale production to fulfill the need for high-quality materials and bulky parts, which are difficult to store, as well as materials for repair work.
Order-based material supply is possible for single or multiple items. In the latter case, it is carried out at equal intervals, for example, weekly intervals, when a single order is formed, taking into account all applications received over a given period.
Material support based on planned targets. This method is based on a deterministic calculation of material requirements. In this case, it is assumed that the primary requirement for a certain period, the product structure in the form of specifications, which makes it possible to determine the dependent requirement, and the possible additional requirement are known.
When supplying materials based on planned targets, the order quantity is determined based on the net requirement, taking into account the planned receipt and the availability of materials in the warehouse. The procedure for such a calculation is presented in Table. . Materials are only ordered if the total requirement exceeds the stock on hand.
Material support based on planned targets
(definition of net - needs)
| Indicator | Calculation procedure |
| 1. Primary Need | - |
| 2. Secondary need | - |
| 3. Additional need | - |
| 4. Total gross - requirement | [ 1 ] + [ 2 ] + [ 3 ] |
| 5. Warehouse stock | - |
| 6. Intended stock | - |
| 7. Planned receipt | - |
| 8. On hand | [ 5 ] - [ 6 ] + [ 7 ] |
| 9. Shop stock | - |
| 10. Net requirement | [ 4 ] - [ 8 ] - [ 9 ] |
Let us explain the concepts of warehouse, cash and workshop stock.
^ Warehouse stock represents the quantity of materials intended for production consumption and available according to the data accounting. In order to determine the real need for materials, the warehouse stock is divided into two parts. One of them characterizes the amount of materials that is allocated for the planned production program, but has not yet been claimed by the shop. The other part is made up of materials that can still be obtained (on-hand stock).
^ Cash on hand is the amount of materials intended for sale and therefore not considered as available.
shop stock are materials received from the warehouse and located in the workshop for the purpose of further processing.
^ Cash on hand is calculated as inventory minus on-hand plus planned receipt.
It is necessary to provide production in connection with the release of node D and its parts. To do this, we calculate the net demand of node D and part I. Part I is used in node D twice and has a lead time of one period. In table. the calculation of the net - requirements for the first and second planning period.
Table
Material support of production based on planned targets
(net calculation - needs for assemblies and necessary components)
| Indicator | The value of the indicator by periods | Total |
|||||
| 1 | 2 | 3 | 4 | 5 | 6 | ||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Start of period 1: | |||||||
| Gross requirement node D | 120 | 220 | 120 | 180 | 200 | 240 | 1080 |
| Continuation of the table. |
|||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Warehouse stock, 400 | -120 | -220 | -60 | 400 |
|||
| Net Demand Node D | - | - | 60 | 180 | 200 | 240 | 680 |
| Gross requirement, detail I (used in node D twice, ahead by one period) | |||||||
| Warehouse stock, 200 | -120 | -80 | -200 |
||||
| Net requirement, detail I | - | 280 | 400 | 480 | 1160 |
||
| Beginning of period 2: | |||||||
| Gross requirement node D | 220 | 120 | 180 | 200 | 240 | 960 |
|
| Warehouse stock, 280 | -220 | -60 | -280 |
||||
| Net Demand Node D | - | 60 | 180 | 200 | 240 | 680 |
|
| Planned receipt | -60 | -40 | -100 |
||||
| Net Demand Node D | - | 140 | 200 | 240 | 580 |
||
| | |||||||
| Gross requirement, detail I Target stock (order-to-order reservation for node D) | 280 80 | 400 | 480 | 1160 200 |
|||
| Warehouse stock, 200 | 120 | 360 | 400 | 480 | 1360 |
||
| Net requirement, detail I | - | 280 | 400 | 480 | 1160 |
||
Material security based on consumption. It involves the timely replenishment of stocks and maintaining them at a level that would cover any need before a new receipt of materials. In accordance with the goal, the problem of determining the time of the additional order is solved, the issue of the size of the order is not considered.
Depending on the type of check and the rules for issuing additional orders, two methods of material supply based on the consumption carried out, known as inventory control systems, are distinguished.
These are the methods:
Ensuring timely orders (fixed order stock management system) and
the necessary rhythm (a system of inventory control with a fixed frequency).
These will be covered in Topic 10, Inventory Management.
^ 5. Methods for calculating supplies
Determining the Economic Order Quantity
Determining the optimal lot size
Subject to wholesale discount
Determination of the optimal order size
Given the deficit
Determining the economic size of the order. The economic order quantity is the size of the batch of materials, which will reduce to a minimum the annual total amount inventory costs under certain conditions of their formation, prices for materials and taxes. The technique for determining economic lot size is to compare the advantages and disadvantages of purchasing materials in large or small lots and to choose the order size that corresponds to the minimum total cost of restocking. The relationship between the order lot size and the cost of purchasing and storing materials is shown in fig. .
Rice. . The ratio between the cost of ordering and maintenance
Stocks and order sizes x
Let x be the number of units purchased as a result of one order. As the number of units of material purchased increases, the running cost of inventory increases (curve A). At the same time, as the batch size increases, the number of orders per year decreases. This leads to a reduction in the costs associated with placing orders (curve B). Let's show this dependence on an example.
As can be seen from fig. , the total annual cost curve has a minimum at x = x 0 .
Let the annual need for materials be 500 units. And there is only one order. In this case, the stock of materials during the year is gradually reduced from 500 units. to zero, which roughly corresponds to an average stock of 250 units. Current inventory costs are determined on an average basis, and ordering costs arise once a year.
Size Average Stock
order is 250 units.
400
1/4 1/2 3/4 1 1/4 1/2 3/4 Time
Rice. . Scheme of continuous consumption of materials
With x = 500 and one order per year
Based on a quantitative assessment of the dependence of the costs of purchasing and storing materials on the amount of material purchased, it is possible to determine the size of the order that minimizes the value total costs under the following assumptions:
1. The total number of units that make up annual stocks of material is known.
2. The amount of demand is unchanged.
3. Order fulfillment occurs immediately, i.e. orders are fulfilled in deadlines, the lead time is known and constant.
4. Registration costs do not depend on their size.
5. The price of the material does not change during the considered period of time.
In accordance with the assumptions made, the costs of creating and maintaining reserves can be expressed by the formula
C \u003d C 1 n + C 2 q / 2,
where C 1 and C 2 are, respectively, fixed and variable costs associated with ordering and storing materials; n is the number of orders per year; q/2 - the average size stock.
Let's take the following cost values: C1 - the cost of supplying a unit of materials - 8.33 den. unit/unit; C2 - annual cost of maintaining stocks - 0.1 den. unit/unit Annual requirement for material Q = 1500 units. Then the economic order size is
From fig. it can be seen that the optimal lot size is in that area of the total cost curve, which has a relatively flat character. In fact, the total costs change as follows: with the size of the ordered batch of 400 units. they amount to 51.24 den. units 
, at 500 units. - 50.00 den. units, at 600 units. - 50.83 den. units and at 700 units. - 52.86 den. units From the above data it follows that with an increase in the batch size by 40% 
compared to its optimal value, there is a slight increase in total costs, by only 5.72% 
.
The above formula establishes the economic batch size for conditions of uniform and strictly defined (deterministic) inventory consumption. In the practice of the enterprise, there may be some partial deviations from these conditions:
1) delayed delivery. In this case, the material arrives within a certain period of time and is partially used before the last batch is delivered.
2) accelerated use. This means that the intensity of inventory consumption is such that there is a certain shortage of material.
Taking into account the noted special conditions, private models are built to determine the optimal batch of the order.
Determining the optimal lot size.
If the enterprise is its own supplier, then the problem of determining the optimal lot size is formulated, i.e., the quantity of products that must be manufactured to replenish the stocks of its own components. The flow diagram of materials, typical for this case, is shown in fig. . 
Production rate
400 Medium
stock
200
100
100 200 300 400 500
Production cycle, t 1
Inventory cycle, t
Rice. . Graph of the movement of the current stock during replenishment
Materials per finite interval
As can be seen from the diagram (Fig.), replenishment of the stock occurs in each cycle during the time t 1, and consumption during the entire cycle t is gradual. The necessary components begin to be manufactured upon receipt of the corresponding order and, as soon as they are ready, they are immediately sent to the consumer: to the warehouse of the recipient shop for further processing or to the picking warehouse of the assembly shop. The daily replenishment rate is determined from the condition
(p - Q) / 240,
where p is the annual volume of production of components.
If the rates of production (receipt) and consumption of materials are set, then the stocks will grow during the entire replenishment period and will reach a maximum value at the end of this period.
Max stock level
Q max\u003d t 1 (p - Q) / 240,
and the average stock will be
Q cf \u003d (t 1 / 2) (p - Q) / 240.
Considering that the replenishment period is determined based on the average daily production volume t 1 = 240 q wholesale/p, the total annual costs associated with the replenishment and storage of materials will be
Where 
- production preparation costs (they largely determine the costs associated with processing and issuing orders), C units. - unit cost of production. Solving this equation with respect to q opt, we obtain the optimal volume of a production batch
.
If the difference between Q and p is close to zero, then q opt approaches infinity. This means that when demand equals output, manufacturing process must be continuous. If p is much greater than Q, then the optimal lot size is equal to the optimal order size, and restocking is possible on demand.
Let's assume that the part is produced in the plant and the pre-production cost is 8.33 den. units /unit The annual consumption of parts is 1500 units, the cost of maintaining a unit of stock is 0.1 den. units, and the volume of annual output is 12,000 units. Please note that we used the listed initial data earlier in Example 5. The optimal size of the production batch will be
= 535 units
The replenishment period will be
11 units
Total cycle time
or 0.35 240 = 84 days.
Determining the optimal order size subject to a wholesale discount. If a volume discount is given, then several calculations must be made to determine the actual order size, since the total cost function is no longer continuous. To find the global minimum of such a function, it is necessary to study its local minima, and some of them may be at price break points.
Assume that a supplier has offered the following prices, taking into account quantity discounts:
Price, den. units Order size
1,60 10000 - 19999
1.40 20,000 or more.
The specific costs of the consumer for the maintenance of stocks are respectively equal to 0.4 den. units, 0.32 den. units And 0.28 den. units Annual consumption 1000000 units. and delivery costs of 28.8 den. units
The optimal order size without discounts at a price of 2.00 den. units equals
= 
= 12000 units
If a 20% discount is given and the price is set at 1.6 den. units
= 
= 13416 units.
At a price of 1.4 den. units we get
= 
= 14350 units
Calculations show that the optimal order size at a price of 2.00 den. units Exceeds the upper order quantity limit (9999 pcs), so any lot size equal to or slightly less than 10000 pcs. will be disadvantageous. Since the calculation of the optimal batch size is based on the determination of the total annual costs, we will compare them only for batches larger than 10,000 units.
We found that for a price of 1.6 den. units Order size = 13416 units taking into account the data obtained, we calculate the total annual costs
C = 
1604293.12 den. units
To find the total annual cost at a price of 1.40 den. units And in the proposed structure of wholesale discounts to the price, we should use the minimum lot size of 20000 units, and not the value = 14350 units calculated above. For this case, the total annual cost will be
C = 
1404240.00 den. units
From the above calculations, we can conclude that it is advisable to purchase in batches of 20,000 units. Buying in larger or smaller lots will be less profitable.
Total
annual
costs
10000 2000 Lot size
Rice. . The effect of the wholesale discount on the total annual costs
The curve of total annual costs for the considered example is shown in fig. (the graph is not drawn to scale, but reflects the type of dependence characteristic of this example).
Determination of the optimal order size under the assumption of a shortage. In the classical economic order quantity model, there is no shortage of products needed for production. However, in cases where the loss due to a shortage is comparable to the cost of maintaining excess inventory, a shortage is acceptable. If available, the model of the optimal batch size requires taking into account certain methodological features. The most general case of the movement of the current stock under the assumption of a shortage of material is shown in fig. 20, where q n - the size of the stock at the beginning of each interval between deliveries t( maximum stock in case of shortage) . The entire interval t divided into two periods:
a) the time during which the stock in the warehouse is available, t 1;
B) the time during which the stock is absent, t 2 . The initial size of the stock q n under these conditions is taken somewhat less than the optimal lot size q opt. The task of inventory management is reduced to a quantitative determination of the size of the reduction and the establishment of the most rational value of the initial stock. The criterion for the optimality of the supply line is the minimum amount of transportation and procurement costs, the cost of maintaining the stock and the loss from the shortage.
The time during which
the stock is expressed in negative
Q 3n denominator
The time during which
the stock is expressed positively
value
Rice. . Cycle of movement of current stocks under the assumption of a shortage
The optimal order size is determined by the formula
. 
,
where C 3 is the loss due to a shortage of production per year.
With a significant increase in C 3 the ratio C 3 /(C 2 + C 3) approaches 1 and the optimal batch size tends to the value that it would be in the absence of stock shortages. If losses due to shortages are very small, then the ratio C 3 / (C 2 + C 3) tends to zero, and the optimal lot size tends to infinity, i.e., a large shortage of stocks is allowed.
Let the optimal lot size x be 500 units. And the loss from the deficit is 0.20 den. units in year. We find
= 613,
= 408.
Total cycle time
T = 
= 0.41 or 0.41 . 240 = 98.4 days.
The above calculations show that in the case when a shortage is allowed, there is a large value of the optimal order size (613 units instead of 500 units) and a long cycle time between order points (0.41 years instead of 0.33 years).
^
Questions for knowledge control
The concept of purchasing logistics
Purchasing process
Types of material requirements
Methods for determining needs
Material support based on planned targets
Determining the Economic Order Quantity
Calculation of the optimal production batch
Optimal order sizes under the assumption of a shortage
Types of material requirements
Under the need for raw materials and materials is understood as their quantity required by a certain date for a specified period to ensure the implementation of a given production program or existing orders.
The need for materials for a certain period is called periodic need. It is made up of primary, secondary and tertiary.
Under primary the need for finished products, assemblies and parts intended for sale, as well as for purchased spare parts, is understood. Calculation of the primary need is carried out using the methods of mathematical statistics and forecasting, giving the expected need. The risk of an incorrect assessment or an inaccurate forecast of needs is compensated by a corresponding increase in safety stock. The primary need is the basis of material flow management in enterprises operating in the field of trade. For industrial enterprises, the primary need should be decomposed into secondary components.
Under secondary understands the need for component parts, parts and raw materials necessary for the production of finished products.
Example. The furniture factory produces work tables for completing kitchen furniture. The sink is located in the table, which, in turn, is completed with a mixer of cold and hot water. The need for a sink and faucets is called secondary, since it can be determined from the primary need (number of work tables). If sinks and faucets are supplied to the distribution network as necessary spare parts, then there is both a primary and a secondary need for these products.
When calculating dependent requirements, the following are assumed to be specified: primary requirement, including information on volumes and terms; specifications or applicability information; possible additional deliveries; the amount of materials at the disposal of the enterprise. Therefore, deterministic calculation methods are used to determine dependent requirements. If this method of establishing the need is not possible due to the lack of specifications or the insignificant need for materials, then it is predicted using data on the consumption of raw materials and materials.
Under tertiary the production need for auxiliary materials and wearing tools is understood. It can be determined based on the secondary on the basis of indicators of the use of materials by conducting stochastic calculations based on the consumption of available materials or by expert means.
Depending on the accounting of cash reserves, there are gross- and net material requirements.
Under gross need is understood as the need for materials for the planning period without taking into account the available stocks in the warehouse or in production. Accordingly, under net need the need for materials for the planning period is understood, taking into account available stocks. It is defined as the difference between the gross demand and the inventory on hand by a certain date.
In practice, the total need for materials increases relative to the gross indicator by an additional need due to defects in production and maintenance and repair of equipment. After comparison with the amount of available stocks, the residual requirement is adjusted by the amount of current stocks. The ratio of different types of requirements for materials is shown in Fig.1.
Fig.1. The ratio of different types of material requirements
End of work -
This topic belongs to:
Theoretical part. Basic concepts of logistics
The theoretical part of the theoretical foundations and functional areas of logistics plan .. the basic concepts of logistics .. logistics has its own conceptual apparatus that includes the terms inherent in its category of concepts..
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