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Economy of the enterprise - Pokropivny SF

11.4. Methods of organization of production

The production process is carried out in time and space. The organization of the production process in time was already considered by us. Spatial organization of the production process involves the placement of workplaces and their groups (plots, shops) on the territory of the enterprise and ensuring the movement of objects of labor on operations with the shortest routes. The combination of these two aspects of the construction of the production process is due to the application of the appropriate method of organization of production. There are two methods of organizing production: imprecise and permanent .

Organization of non-production

The following features are inherent to non-thread production: work items of various design and technology are processed at workplaces, for the quantity of each is small and insufficient for the normal loading of equipment; Workplaces are placed with the same type of technological groups without a definite link to the sequential execution of operations, for example, a group of turning, milling, drilling and other machine tools; Objects of labor move in the process of processing along complex routes, as a result of which there are large reserves for reducing breaks between operations. After separate operations, labor items often arrive at intermediate warehouses and await the release of the workplace for the next operation.

The non-flow method is mainly used in single and batch production. Depending on the nomenclature of products and their quantity, it can have various modifications. Usually three modifications are applied: single-technological, partion-technological and subject-group (Fig. 11.6).

In the conditions of a single production, a non-direct method is carried out mainly in the form of a single-technological modification, when individual objects of labor in units or small batches that do not repeat are processed in accordance with the procedures given above. In serial production, this method takes the form of a batch-technological or object-group modification.

Partionno-technological meodification differs from the single-technological one in that the objects of labor come in batches that are periodically repeated. The party of labor objects is an important calendar and planning standard for the organization of party production and its magnitude significantly affects its effectiveness. This influence is not unique. Of course, increasing the lot size ensures a reduction in the number of changes in equipment, as a result of which its use improves, the costs for preparatory and final works are reduced (adjustment, receipt and delivery of work, familiarization with technical documentation, etc.). In addition, operational planning and recording of production are simplified. However, the processing of items in large batches increases the amount of work in progress, requires large storage facilities, and hence additional costs.

Reducing the size of shipments of objects has an opposite effect on the efficiency of production. This explains the importance of determining the optimal batch size. In general terms, we can say that the optimal is a batch of items, which requires minimal total costs for its production. It is calculated in the process of operational management of production.

Single and partion-technological modifications of the inexpensive production method are very complex. Their shortcomings are somewhat weakened by the application of the subject-group method. The essence of the latter is that the whole aggregate of objects of labor is divided into technologically similar groups. The processing of the objects of each group is carried out according to approximately the same technology and requires the same equipment. This allows you to create subject-specific areas for processing a group, to increase the level of mechanization and automation of production. Subject-group methods create the prerequisites for the transition to in-line production.

The quantity of equipment in the non-exact production is determined separately for each group of the same type, technologically interchangeable machine tools:

(11.11)

Where M is the number of machines (machines) in the technological group;

N - the number of items to be processed on this equipment;

Ni - the number of items of the i- th name, processed for the billing period (usually per year);

Ti - the time norm for processing the i- th item, hours;

Т р - planned fund of time of work of units of the equipment for the settlement period;

К н - the coefficient of the fulfillment of the norm of time.

Equipment in non-flax production is predominantly universal, and workers are universals of high qualification. A higher level of specialization of equipment, as noted, is used in the case of application of group-object modification, since a smaller number of details of operations can be assigned to a certain subject-specialized area.

For inconsistent methods, a consistent (rarely sequentially-parallel) combination of operations is characteristic, which along with complex processing routes increases the duration of the production cycle. However, inaccurate production has a wide scope of application: it is used in industrial discrete processes. With small volumes of individual products, a non-accurate method ensures better utilization of the equipment, more complete utilization of it in time and in power, since the processing of objects can be distributed among the group machines, taking into account their parameters.

General Characteristics of In-line Production

Stream production is a highly efficient method of organizing the production process. In the conditions of flow, the production process is carried out in accordance with the principles of its rational organization. Stream production has the following features:

• For a group of workplaces, the processing or assembly of items of one name or a limited number of designations of constructively and technologically similar items is fixed;
• Workplaces are placed sequentially in the course of the technological process;
• The technological process has a high operational differentiation, one or several similar operations are performed at each workplace;
• Objects of labor are transferred from operation to operation per piece or small transport batches in accordance with the rhythm of work, which ensures a high degree of parallelism and continuity of the process.

Widely used special inter-operational transport (conveyors), which performs not only the functions of moving objects, but also sets the rhythm of work.

Flow methods are used to manufacture products in significant quantities and for a long time, i.e. in mass and large-scale production.

The main structural link of on-line production is the production line - a technologically and organizationally allocated group of jobs that produces one or several similar product sizes. The flow lines are different, so they are classified according to certain characteristics (Table 11.3).

Table 11.3

CLASSIFICATION OF STREAM LINES BY SEPARATE CHARACTERS

According to the nomenclature of products, the production lines are divided into one - and multi-subject . A single line is the line on which a product of the same size is processed or assembled for a long time. For the transition to the manufacture of products of a different size, the lines need to be reorganized (repositioning of the equipment, its replacement, etc.). These lines are used in mass production. A multi-objective is a production line, on which several types of products, similar in construction and production technology, are produced simultaneously or sequentially. Scope - serial production.

By the degree of continuity of the process, the production lines are divided into continuous and discontinuous . Continuous is the line on which the objects of labor move through operations continuously, i.e. without inter-operational expectation (parallel combination of operations). Discontinuous, or co-current, is a line that can not provide continuous processing of objects due to non-synchronous operations. Between operations with different productivity, the objects of labor await their turn for processing, forming periodic circulating stocks.

By the way the rhythm is supported, lines with a regulated and free rhythm are distinguished. On a line with a regulated rhythm, the objects of labor are transferred from the operation to the operation at precisely the specified time, i.e. in accordance with a given rhythm maintained by means of special means (most often a conveyor). The regulated rhythm is applied on continuous lines. On lines with a free rhythm objects from operation to operation can be transmitted with a deviation from the calculated rhythm. The overall rhythm in this case is ensured by the stable productivity of the worker at the first operation of the line or rhythmic signaling (sound, light).

Depending on the place of operations, the lines are divided into lines with a working conveyor and a conveyor with removal of objects for their processing. The working conveyor, except for transportation and support of the rhythm, is the direct place of operations. Such are the so-called assembly conveyors. Conveyors with removal of objects are characteristic for processes, whose operations are performed on technological equipment.

Conveyors with continuous and pulsating motion are distinguished by the method of transport. The conveyor with continuous motion has a constant speed and does not stop during operation. The conveyor with pulsating motion during the operations is stationary. It is activated periodically through a period of time, which is equal to the line's clock. Such conveyors are used when, under technological conditions, the performance of operations requires the immovable state of the object of labor.

Moving objects is not always possible and expedient (for example, in the process of assembling large-sized machines). In this case, a so-called stationary flow is organized, when the products are fixed on assembly stands, and specialized groups (brigades) of workers performing certain operations are moved. The number of groups (brigades) of workers is determined by the number of stands.

Features of the organization and parameters of the flow lines

The introduction of on-line production requires certain conditions. The main ones are:

• Sufficient output volume and extra-long duration of the production line;
• High stability and technological design of the product;
• The possibility of rational allocation of jobs and a clear organization of their services;
• Application of advanced technology, mechanization and automation of production processes.

Based on the analysis of products, the volume of its release, the state of the technological process, the possibilities for its improvement, the mass and dimensions of the products, a certain type of production line is chosen and its main parameters are calculated: the rhythm, the number of workplaces, the length of working areas, and the speed of the conveyor.

• The flow line cycle is the time interval through which the products move one after the other:

(11.12)

Where r is the stroke of the production line, min .;

Т р - planned fund of work time of a line for the settlement period, mines;

N - the volume of production for the same period in the natural measurement.

Calculating the running time of continuous production lines, it is necessary to take into account periodic short-term breaks in the work of the conveyor belt for workers' rest.

• If objects of labor are transferred not individually, but by transport parties ( nm ), then they leave the line at certain intervals, called the rhythm of the line :

(11.13)

Where R is the rhythm of the lines, min .;

In the case where a continuous production line is organized, synchronization of operations is carried out after the determination of the clock. Operations are considered synchronized when the duration of each of them is equal to or is a multiple of the line clock. Synchronization of operations is achieved by a number of technological or organizational measures: differentiation, concentration of operations, reduction in their duration due to certain improvements, etc.

• The number of jobs is calculated for each operation by the formula

(11.14)

Where - The estimated number of jobs in the ith operation. It is rounded to a larger integer M, after which the workload factor (K3) for each operation ( i ) is calculated:

(11.15)

• Conveyor speed in m / min. ( V ) depends on its tact and the distance between products:

(11.16)

Where l is the distance between the centers of two adjacent products on the conveyor, m.

The speed of the conveyor, which moves continuously, is limited to a rational mode of work. On a pulsating conveyor, which is switched on periodically, it is set to the maximum, taking into account the safety rules of labor.

• On the working conveyor with continuous movement and movement of the worker within the working area assigned to it. The length of the working area is determined by the formula:

(11.17)

Where L i is the length of the working area, m.

When processing or assembling small products and the low speed of the conveyor, the worker can sit in one workplace (assembling the clock, installing radio equipment and sub).

The spatial arrangement of the production lines can be different depending on the number of workplaces, the type of vehicles, and the area of ​​the sections (workshops). The simplest and most common is the straightforward placement of jobs in the process. But this is not always possible, so a two-row, circular, zigzag arrangement is used. Adjacent production lines should be placed so that it is convenient to transport objects of labor between them. In the case of the organization of line processing and assembly of products, auxiliary lines providing the assembly conveyor are placed perpendicular to it.

Trends in the development of in-line production

Stream production due to high specialization, mechanization and a clear organization of the production process is highly effective. Its effectiveness is manifested in high labor productivity, a reduction in the production cycle and in-process production, better use of fixed assets. All this ensures a reduction in production costs. At the same time, line production has certain drawbacks.

The most notable of these is the primitivization of workers' labor, limiting it to the performance of elementary mechanical operations, which is a consequence of the high differentiation of the technological process. This makes labor on the production line insubstantial, contrary to the general trend of increasing the educational and qualification level of workers. Quite unattractive is the hard rhythm of work on the production lines, the absence of the most elementary creative elements in labor.

This lack of in-line production is overcome by its automation and creation of automatic production lines. Ныне автоматические линии широко применяются в массовом производстве.

Как существенный недостаток поточного производства в его традиционной узкоспециализированной форме можно назвать и противоречие между его тяготением к конструктивно-технологической стабильности (то есть его консерватизмом) и требованиями динамичности производства, постоянного обновления продукции в соответствии с научно-техническим прогрессом и потребностями рынка. Узкая специализация рабочих мест, их жесткая привязанность к ходу технологического процесса создают трудности для перехода на выпуск новой продукции. Возникает необходимость в замене оборудовании, его перемещении, создания новой оснастки, переквалификации рабочих, что связано с большими затратами времени и средств.

Эта отрицательная сторона поточного производства постепенно нейтрализуется повышением гибкости технологических систем, применением станков с числовым программным управлением, внедрением автоматических многофункциональных манипуляторов-роботов.
Объединение станков с ЧПУ, роботов, автоматических транспортных средств и складов под общим управлением с помощью ЭВМ позволяет создавать гибкие автоматизированные системы (ГАС) с дальнейшим приобщением к ним автоматического проектирования продукции. Такие системы соединяют преимущества поточного (высокая производительность) и непоточного (гибкость) производства, могут применятся во всех его типах, и являются особенно эффективными в серийном производстве.

Они быстро и без больших затрат времени и средств переналаживаются на выпуск другой продукции (в переделах технических возможностей). Для этого необходимо всего лишь изменить программу производственного процесса, записанную на машинном носителе. Гибкие автоматизированные системы — стратегическое направление развития техники и организации производства.