Guidelines for practical work No. 3

“NETWORK PLANNING OF SCIENTIFIC AND TECHNICAL PREPARATION OF PRODUCTION”

Developed by Associate Professor, Ph.D. Prokhorov Yu.K.

Network planning of scientific and technical preparation of production

Formulation of the problem

A team of developers (researchers, designers, technologists, programmers, etc.) was given the task of developing the project and a deadline for completing the development was set. It is necessary to plan the development progress using the network planning and management method (NPC), which would ensure the completion of all work within a given target period.

Exercise

Based on the proposed list of works, it is necessary to create a network model (network graph) of project development, determine the expected duration of the work, calculate the parameters of the network model, determine the probability of completing the project within a given target period and evaluate the quality of the developed network model, optimize the network model, develop a work distribution schedule .

1. Basic concepts and definitions

A network model is a graphical representation of a technological sequence and connection of events that represent the result of one or more activities.

An event cannot be expressed in time - it represents the end of the work included in it.

In the network model, an event is represented by a circle with the event number indicated in it.

Work is any process that precedes the completion of an event. Work in the network model is depicted by an arrow.

There are:

Real work, i.e. requiring labor and time;

Waiting work that requires only time investment;

Fictitious work - a logical connection between two events, indicating that the data obtained during the completion of the preceding event are necessary for the completion of the subsequent event. In this case, there is no waste of time and resources. Fictitious work is represented by a broken arrow.

All work through intermediate events leads to the final event, which means achieving the goal outlined in the program.

Any continuous sequence of activities and events forms the paths of the network model.

Critical path is the complete path (from the initial to the final event) of maximum duration.

2. Rules for constructing the topology of the network model

A schematic representation of events and activities, showing their relationships, forms a topological model of the development process.

In order to avoid mistakes and related further incorrect decisions when building a network model, the following rules must be observed:

1. The network model is built from left to right: from the initial event to the final one.

2. The length of the arrow depicting the work does not express the duration of the work (the model is not built to scale).

3. The expected duration of work is indicated in the corresponding time estimates (days, weeks) above the arrow.

4. It is inappropriate to depict on a model work lasting less than the accepted unit of measurement (one day, one week), because This granularity makes ongoing management across the network difficult.

5. Works are coded by initial numbers ( ith) and final ( j th) events, and the code j th work events cannot be less than code ith work events.

6. In the network model, there should not be a single event, other than the initial one, that does not include any work.

7. In the network model there should not be a single event, except for the final one, from which no work would come out.

8. The network model should not contain works with the same codes, i.e. with common start and end events. If work ATo (k = 1, 2 ..., n) begin and end with events common to these jobs (Fig. 1), then in order for all these jobs to have different codes, it is necessary to enter into the network model (n-1) fictitious works Bt (t = l ,2..., n-1) (Fig. 2)

9. When building a network model, you should avoid crossing arrows whenever possible.

3. Determination of duration of work

One of the most important steps in constructing a network model is obtaining correct estimates of activity durations. The duration of work can be determined either by existing standards or using expert probabilistic estimates.

Formulas for determining the expected duration of work using the second method, depending on the number of expert estimates, are presented in Table. 1.

Table 1

Calculation dependencies for establishing the expected duration of work

and its variance based on expert assessments

Parameter name	Calculation formula
Expected duration of work based on three expert estimates
Expected duration of work based on two expert estimates
Dispersion (a measure of spread) of expected work duration with three estimates
Dispersion (measure of spread) of expected work duration under two estimates

Legend to the table:

tmin– the minimum duration of work, selected from the condition that the work will take place under the most favorable circumstances;

t nv– the most probable duration of work, chosen under average conditions in which no unexpected difficulties arise;

tmax– the maximum duration of work, selected from the conditions for performing this work under the most unfavorable set of circumstances.

4. Calculation of network model parameters

Reducing the duration of production processes is one of the most important tasks in organizing modern production, on the proper solution of which its effective, cost-effective operation largely depends.

This problem can be solved by introducing modern principles and methods of organizing production.

The organization of processes for creating new types of products covers the design, implementation in practice and improvement of the production preparation system. The production preparation system is an objectively existing complex of material objects, teams of people and a set of processes of a scientific, technical, production and economic nature for the development and organization of the production of new products.

The organization of preparation for the production of new products is aimed at the rational combination of all elements of the process of creating and mastering new technology in space and time, establishing the necessary connections and coordinating the actions of participants in this process, creating conditions for increasing the interest of scientists, engineers, and production workers in the accelerated development and organization of production of new highly efficient technology.

In conditions of complex production preparation, there is a need to apply the following methods of work planning and management:

methods of network planning and management that allow you to most fully cover the interconnections of the entire complex of work on production preparation;

methods for managing the progress of work: assigning deadlines for work performed, planning resources, determining the technical and economic parameters of the equipment being created;

methods of material and moral incentives for workers involved in the creation of new products, taking into account their contribution to reducing time and costs, achieving high technical and economic parameters of new equipment.

Let's consider the network planning and management method (NPM) in more detail. It makes it possible to coordinate in time the production of work included in a closed complex, sometimes numbering up to several thousand components. It allows you to plan in advance the sequence and interdependence of work, monitor the implementation of each work separately, identify and eliminate delays, as well as find hidden reserves and outline ways to use them. In addition, the SPU method allows you to determine the work on which the time for solving the entire complex of problems primarily depends; it allows you to highlight the least important secondary work that can lead to such undesirable consequences as an increase in their cost, downtime of performers, equipment, etc. . Also, when solving the listed issues, it allows you to approach not only from a qualitative, but also from a quantitative side, to indicate those works on the implementation of which the time for solving the entire complex also depends.

SPU methods are based on a graphical representation of a certain set of works, reflecting their logical sequence, relationship and duration, with optimization of the developed schedule using methods of applied mathematics and computer technology and its further use for the ongoing management of these works. 5

When applying SPC methods, the model of the planned process is depicted in the form of an oriented graph - a network in which the entire complex of works is divided into separate, clearly defined works. The concept of “work” in a network diagram denotes processes or a set of processes and can have the following meanings:

actual work is a labor process that requires time and resources, for example, the production of a prototype, its testing, etc.;

waiting - a process that requires time, but does not require resources, for example, drying, etc.;

fictitious work - an image of a logical connection between works; it is introduced to reflect the correct relationship of work and shows the exact order of their implementation.

Every work on a network diagram connects two events: the one immediately preceding the work, which is the initial event for it, and the one following it, which is the final event for it. An event can be the beginning of a set of works, the achievement of a final goal, etc. Unlike work, an event is not a process and has no duration. The duration of work, depending on the task, is characterized by various quantitative estimates: labor intensity, cost, material resources necessary to complete it, etc.

A sequence of activities in a network in which the final event of each activity coincides with the initial event of the activity following it is called a path. The duration of any path is equal to the sum of the durations of its constituent works. The full path, which has the longest duration, is called critical; its duration determines the total duration of the work package, therefore, in order to reduce the time required for completing the work package, it is necessary to reduce the time for completing the work lying on the critical path. On the network diagram, the critical path is highlighted with bold arrows. This advantage is especially important when implementing complex work packages that involve dozens and hundreds of departments and organizations performing the work. The remaining paths have a reserve time, which is defined as the difference between the late and early deadlines for completing their work. Activities that have zero slack are on the critical path and are called critical. The travel time reserve can be used entirely for one job or distributed among individual jobs located on this path only within the full time reserves of these jobs. If the entire travel time reserve is used entirely for one job, the time reserves of the remaining jobs lying on the maximum path will be exhausted. The time reserves on other paths passing through it will decrease and will be equal to the difference between the previous time reserve of these works and the used full time reserve of the work lying on the maximum path. In addition to full time reserves for work at intersections of paths of different durations belonging to paths with shorter durations, there are two types of time reserves.

Private reserve of the first type is formed in works immediately following events in which paths of different durations intersect. Its value shows what part of the total work reserve can be used to increase this and subsequent work belonging to the section of the path before the intersection with paths of longer duration, provided that this increase does not cause a change in the late date of the event that begins this work.

Private reserve of the second type is formed by works immediately preceding events in which paths of varying durations intersect. Its value shows what part of the total reserve can be used to increase the duration of the work and the duration of the work preceding it on the section of the path before the intersection with paths of longer duration, provided that this increase does not cause a violation of the early deadline for the completion of the final event of this work, and therefore reduction of time reserves for any of the subsequent work.

Fig 5.

Time reserves are used in control systems for sequential restructuring of the schedule in order to optimize it. When monitoring its implementation, the amount of time reserve cannot always sufficiently fully characterize how intense the implementation of the adopted work plan is. Depending on the number of independent goals in specific work packages, the network diagrams describing them may contain one (single purpose), or several ( multi-purpose) final events.

According to the degree of coverage of the work package, network diagrams are divided into: complex (consolidated), covering all work performed by various organizations; private, including individual independent works of the complex performed by separate organizations; primary, containing work performed by individual responsible performers.

The listed network diagrams can be detailed or enlarged.

A network diagram can have the following types of structures: deterministic, which means that all types of work of a set of works and their relationships are precisely defined; random, if the works are included in the work package with some probability; mixed, when some work in the network diagram is probabilistic in nature.

To compile networks, it is necessary to accumulate a large amount of statistical material, as well as to use the labor of highly qualified specialists. Despite this, the effectiveness of network planning and management is great, especially for such work as the design of new types of equipment based on new scientific principles, the manufacture and installation of the most complex types of technological equipment, the capital construction of complex facilities, and complex work performed by many enterprises in the industry.

The use of network planning methods helps reduce the time required to create new facilities by 15-20%, ensuring the rational use of labor resources and equipment. 6

This is the best way to find information on the site.

Network planning for production preparation

from "Organization of production"

Network planning systems are a set of graphical and calculation methods, organizational and management techniques that allow modeling of complex processes for creating new equipment and operational management of the progress of work on its creation. The main planning document in the network planning system is the network schedule.
Construction of a network diagram. In the network model, events are indicated by circles, jobs - by arrows. The constructed graph must have one initial and one final event. An event is an intermediate or final result of one or more activities. It does not have a duration in time, but indicates the beginning of some work and can simultaneously be the completion of others.
In a network diagram, work is understood as any process that requires labor; waiting; requiring a certain amount of time; dependency, indicating that the start of a given job depends on the completion of the previous one. Graphically, the work is indicated by a solid arrow. An arrow that expresses only the dependence of one job on another is called a fictitious job and is indicated by a dotted line. It has a zero time rating. Work requires a lot of time. The duration of work in days (weeks) is shown above the arrow.
Any sequence of activities connecting the initial event with the final event is called a path. The path with the longest duration of work is called critical and is depicted with bold arrows.
Activities on the critical path have no slack. Therefore, failure to meet deadlines for any work on the critical path leads to a delay in the overall deadline for completing the entire complex. Activities that are not on the critical path have a slack time.
If the calculation of the early dates for the completion of an event is carried out from left to right, from the initial event to the final one, then when determining the later dates for the completion of events, the calculation must be carried out from right to left, from the final event to the initial one.
The main tasks of improving production preparation in modern conditions are to accelerate the processes of creating and introducing new equipment into production, increasing the efficiency of production preparation and mastering new types of products. Specific ways to solve these problems are implemented as a result of the search and use of internal production reserves.
The reserves for improving the preparation of production for the release of new products are unused opportunities to further reduce the time and costs of creating new equipment, improve the quality and efficiency of the created equipment. These reserves are divided into three large groups: accelerating the preparation of production for the release of new products; reducing the costs of developing and mastering the production of new products; increasing the technical level and efficiency of new types of products.
The use of reserves for accelerating production preparation should ensure a reduction in the period of development, development and introduction into production of new types of products.
The use of reserves for reducing production preparation costs ensures a reduction in labor costs, material resources and funds for the creation of specific types of new products.
Ш technical reserves - reserves for reducing production preparation time and costs due to mechanization and automation of work and development of the material and technical base for production preparation 111 reserves for improving production preparation management, i.e. reducing time and costs based on improved quality of management of the processes of creation and implementation of new technology. The process of creating new products requires significant labor, material and financial resources. But the new technology being created ensures savings in living and embodied labor during its production and operation. Comparison of the costs of new technology with the economic effect obtained from its implementation shows the economic efficiency of the new technology. The efficiency of the work performed during pre-production is reflected in the efficiency of the equipment being created. Hence the main economic task of preparing production at the lowest possible cost is to create technically advanced equipment that ensures the highest economic effect when introduced into production. Solving this problem requires the use of reserves for increasing the technical level and efficiency of the equipment being created.
These reserves, in turn, can act as design, technological and organizational-technical ones. Design reserves are reserves for improving the quality of products, reducing the costs of their manufacture and increasing the efficiency of operation by improving the designs of the equipment being created. Technological reserves are reserves for maintaining the quality of products and increasing the efficiency of their production and operation based on the use of progressive solutions in the process of technological preparation of production. Organizational and technical reserves are reserves for improving the quality and efficiency of new products by improving the organization of production preparation.
This group of indicators (Table 6) gives an idea of ​​the economic results of organizing the process of creating new equipment.
Share of new products in the total volume of output, % Y = -xYO p QH - volume of new products, r. p - total volume of production, rub.
Product renewal coefficient K = - xYO Qoe - volume of products mastered by production in the current year, rub.
Using the given system of technical and economic indicators, it is possible to analyze the state of production preparation at enterprises in the mechanical engineering industry. At the same time, the following types of analysis are distinguished II analysis of technical and economic indicators of the state of production preparation of a given enterprise 11 comparative analysis of the state of production preparation for a group of related enterprises in the industry II analysis of production preparation for one or a group of similar products of new technology. The purpose of analyzing the technical and economic indicators of production preparation for any particular enterprise is to establish the state of preparation organization and reveal the possibilities of reducing the time required to create new products, reducing production preparation costs, and improving the quality and efficiency of new equipment.
A comparative analysis of the state of production preparation for a group of related enterprises in the industry reveals opportunities to reduce the time and costs of production preparation and achieve a high technical and economic level of the equipment being created.
The purpose of analyzing production preparation indicators for one or a group of similar products of new technology is to get an idea of ​​the level of work at the preparatory stage and to determine the possibilities of reducing work time, costs for creating products of this type, improving their quality and efficiency.
The FSA process identifies opportunities to reduce additional costs and create high-quality structures with costs approaching target levels.

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After the calculation of the marked numerical parameters has been carried out for each of the network diagrams, the SPU service, on this basis, draws up a calendar schedule for the execution of work due to the preparation for mass production of all products of the planned quarter. If it is possible to obtain a schedule in which the process of preparing the production of each product is completed within an acceptable time frame, then one of the acceptable schedules is obtained. If not, then an analysis is made of the possible reduction in preparation time for the production of individual products by changing the composition or sequence of work in order to reduce the duration of the critical paths of the corresponding network diagrams, reduce the duration of individual work (primarily the work of critical paths), and more rational use or attracting additional resources, varying the start and end dates of work on critical paths, taking into account a more rational use of resources.

As a result of repeated sequential improvement of the initial work plan, it is possible either to obtain an acceptable schedule, or to come to the conclusion that given the limitations, determined primarily by the actual availability of resources, all products cannot be prepared within the agreed time frame. The latter is the basis for revising individual target dates for preparing the production of specific products or serves as a prerequisite for attracting additional resources. In this regard, the most appropriate final decisions for the given production association (enterprise) are made on the timing of completion of preparation for production of products and the use of resources, and a draft schedule is drawn up. On its basis, the recommended start and finish dates for work related to the preparation for production of each specific product are determined, a calendar plan is a recommendation for the work to be performed by each of the performers for a certain period of time, a resource consumption schedule, time parameters of degrees of freedom indicators necessary for analyzing and adjusting the plan - recommendations when making management decisions. After the SPU service has drawn up a schedule for preparing the production of products of a new range and, in order to implement it, has issued the corresponding task plans for the execution of work by each of the performers, the service monitors and records the progress of the planned work, identifying and analysis of emerging deviations between the planned and actual progress of work. On this basis, appropriate control actions are provided to ensure that any deviations that have arisen are eliminated, i.e., the progress of work is operatively regulated. Daily collection of information about the actual implementation of planned work is carried out by the control system service. To do this, at the beginning of each working day, one of the service workers looks through all the control cards and studies the actual status of the work for the current day, specified in these control cards. In addition to the information received by the employees of the SPU service in the process of studying the actual progress of work, relevant information is received from those in charge performers. This information is issued only in cases where there are any deviations in the actual progress of work from the planned one, namely, when new work appears or the need to perform previously envisaged work disappears, the wording of existing work and events changes, and the duration of work and actual their start and end dates. In all these cases, the responsible executive informs the SPU service about the changes that have occurred (Form 4). All information collected by the SPU service is processed, and on this basis, appropriate changes are made to the schedule and operational decisions are made aimed at eliminating deviations in the actual progress of work from the planned one. If it is not possible to eliminate the deviations that have arisen, then the SPU service adjusts the schedule for preparing the production of new products and the corresponding changes are communicated to the responsible executors. Thus, it is shown in detail how to solve all the main problems of managing the preparation of production of new products based on the use of network diagrams. Further improvement of the described production preparation management system would be the use of computers and economic and mathematical methods to find solutions to the problems described above. At the same time, as the experience of production associations and enterprises shows, computers should be used in stages to solve the problems of managing the preparation of production of new products in each specific enterprise, gradually freeing a significant number of management employees from the labor-intensive work of primary information processing. Ultimately, with the use of computers, the problems of finding optimal schedules for preparing the production of new products must be solved. Their determination and adjustment should be made in the computer center (CC) on the basis of information coming from the SPU service, as well as from responsible executors. When drawing up calendar plans, it is advisable to use methods and algorithms determined by specific situations for finding solutions to scheduling problems, determined by the appropriate formulation of each specific task, as discussed in detail above. The draft optimal calendar plan for preparing the production of new products, calculated in the computer center, is issued to the SPU service, after which it is agreed upon by the employees of this service with the responsible persons and approved by the chief engineer of the given enterprise or production association. From the moment of its approval until the completion of the entire range of work provided for in preparation for the production of new products in accordance with the drawn up plan, operational regulation of the progress of the work performed is carried out. To do this, the computer center receives daily operational information about the actual implementation of planned work. On its basis, the center compiles various reports and documents during the actual execution of work. This output information is sent to the control system service and is used by the heads of various departments when making decisions aimed at eliminating bottlenecks that have arisen. The output information is structured in such a way that each manager receives only the information that is necessary for him and is sufficient for analysis and making management decisions. In addition to issuing various reports and documents on the actual progress of work, once a month in the computer center, in accordance with the assessment of the progress of work, operational plans and schedules for preparing the production of products for the next one to two months are formed. After approval, the schedules are communicated to responsible executors through the SPU service.

"St. Petersburg State Technological Institute

(Technical University)"

UGS (code, name)_____________________________________________

Specialty (specialization)_________________________________

Faculty_____________________________________________________

Department ______________________________________________________________

COURSE PROJECT

Topic: “Network planning and management of technical training

production of new products using the example

Student _________________ __________________

Supervisor,

job title ________________ ___________________

(signature, date) (initials, surname)

3) Subprogram for the design and manufacture of non-standard equipment and accessories;

4) Subprogram for technological development of production of new products to the specified design level.

For each subprogram, local network graphs are built, which are then stitched into a general network graph of the target scientific and technological program.

Decisions made under subprogram 1. Decisions under the subprogram provide for the use of high-tech technological processes; its implementation should begin after receiving fully revised technological documentation based on the results of testing prototypes of new products. Depending on the novelty of technological processes, decisions are made on the reconstruction of workshops and the layout of production areas.

The most important solutions for updating production technology should be considered the widespread use of CNC equipment in combination with robotic devices. Accordingly, the management system is also subject to change, as production becomes more flexible, focused on individual orders of product consumers. The primary organizational element in the management of flexible automated production (FAP) is a flexible production module (FPM), operating in autonomous mode. Several technologically connected GPMs and an automated transport and warehouse system (ATSS) form a flexible automated section (GAS). In turn, GAUs of different technological purposes, united by common production tasks, are included in the organizational structure of a flexible automated workshop (GAS).

In conditions of frequent changes in manufactured products, production flexibility is complemented by functional computer-aided design (CAD) systems and an automated system for technological preparation of production (ASTPP). At the same time, the possibilities for the effective use of automated control systems depend on the information content of design and technological classifiers, determined by the level of continuity of design solutions in CAD.