Flow production: organizational and economic characteristics. Release is the inverse value of the release cycle. The production cycle of products affects

Takt time is one of the key principles of lean manufacturing. Takt time sets the speed of production, which must exactly match the existing demand. Takt time in production is similar to the human heart rate. Takt time is one of the three elements of a just-in-time system (along with in-line production and the pull system) that ensures work is evenly loaded and identifies bottlenecks. For design production cells, assembly lines and creating lean manufacturing, an absolute understanding of takt time is necessary. This article discusses situations in which an artificial increase or decrease in takt time is possible.

What is takt time? The word tact comes from the German takt, which means rhythm or beat. The term beat time is related to musical terminology and refers to the rhythm that the conductor sets so that the orchestra plays in unison. In a lean production system, this concept is used to ensure the rate of production with the average rate of change in the level of consumer demand. Takt time is not a numerical indicator that can be measured, for example, using a stopwatch. The concept of takt time must be distinguished from the concept of cycle time (the time it takes to complete one operating cycle). The cycle time can be less than, greater than, or equal to the takt time. When the cycle time of each operation in a process becomes exactly equal to the takt time, one-piece flow occurs.

There is the following formula for calculation:
Takt time = available production time (per day) / customer demand (per day).

Takt time is expressed in seconds per product, indicating that consumers purchase products once every certain period of time in seconds. It is incorrect to express takt time in units per second. By setting the pace of production in accordance with the rate of change in consumer demand, lean manufacturers thereby ensure that work is completed on time and reduces waste and costs.

Reduced takt time. The purpose of determining takt time is to work according to customer demand. But what happens if takt time is artificially reduced? The work will be completed faster than required, resulting in overproduction and excess inventory. If other tasks are unavailable, workers will waste time waiting. In what situation is such an action justified?

To demonstrate a similar situation, let’s calculate the required number of workers on an assembly line on which the flow of single products is carried out:

Group size = sum of manual cycle times / takt time.

Thus, if the total cycle time for a process is 1293 s, then the group size will be 3.74 people (1293 s / 345 s).

Since it is impossible to employ 0.74 people, the number 3.74 must be rounded. Three people may not be enough to keep production pace in line with changing consumer demand. In this case, improvement activities must be carried out to reduce the cycle time of manual operations and eliminate waste in the process.

If the cycle time is fixed, then it is possible to round up by reducing the takt time. Takt time can be reduced if available production time decreases:

3.74 people = 1293 s per product / (7.5 hours x 60 min x 60 s / 78 parts);
4 people = 1293 s / (7 hours x 60 min x 60 s / 78 parts).

By employing four people, reducing takt time and producing the same volume in less time, the team's workload is evenly distributed. If these four people can keep production up to speed with customer demand in less time than usual, they will need to be rotated or assigned to process improvement issues.

Increasing takt time: 50 second rule. In the example above, we show when takt time can be reduced to improve efficiency. Let us now consider the case where the takt time should be increased.

A rule of thumb is that all repetitive manual operations should have a cycle time of at least 50 seconds (start to start time). For example, the operation of company assembly lines Toyota determined by the takt time 50 60 s. If the company needs to increase production volume by 5-15%, then introduce Extra time or in some cases using multiple assembly lines configured for longer takt times (for example, two lines with a takt time of 90 s instead of one line with a takt time of 45 s).

There are four reasons why the 50 second rule is important.

1. Performance. If the takt time is small, then even seconds spent as a result of unnecessary movements result in large losses of cycle time. Losing 3 s out of 30 s cycle time results in a 10% reduction in productivity. Losing 3 seconds out of a 60 second cycle results in a 5% reduction in performance. Losing 3 s out of a 300 s cycle to only 1%, etc. Therefore, if the takt time is a larger value (50 s or more), then this will not be a significant loss in productivity.
   Using one assembly line with a large number of operators working in a short takt time (eg 14 s) saves on investment costs (number of lines), but will result in higher operating costs. We have found that assembly lines designed to operate at speeds of 50 seconds or more are 30% more productive than lines with low takt times.
2. Safety and ergonomics. Performing the same manual tasks for a short period of time can lead to fatigue and muscle pain due to repetitive strain. When various operations are performed over a longer period of time (for example, in 60 seconds instead of 14 seconds), the muscles have time to recover before starting the operation again.
3. Quality. By performing a wide range of responsibilities (for example, five operations instead of two), each employee himself becomes an internal consumer of every operation except the last one. If a worker performs five operations, this forces him to pay more attention to quality, since an unsatisfactory result in operation 3 will be reflected in the performance of operation 4 and, therefore, will not be passed on unnoticed to the next stage.
4. Attitude to the work performed. It has been noted that workers experience greater job satisfaction when performing a task repeatedly, For example every 54 s, not 27 s. People enjoy learning new skills, they experience less fatigue when performing repetitive movements, but most importantly, employees feel that they are making a personal contribution to the creation of the product, and are not just doing mechanical work.

Takt time and investment. The importance of the 50 second rule can be illustrated by the example of a company engaged in the production and assembly of pumps for industry. The company used one long assembly line to create its product. As a result of increasing customer demand and additional testing requirements, the design of a new assembly line became necessary. On at this stage The company decided to apply lean manufacturing principles. One of the first steps was to determine takt time.

The takt time for this product of 40 s was calculated based on the highest demand. Considering the 50 second rule, the engineers responsible for this project, decided to design either one assembly line with a takt time of 80 s, operating in two shifts, or two conveyors with a takt time of 80 s, operating in one shift. Work on designing the assembly line was offered to several engineering companies. According to their estimates, the design of one line required from 280 to 450 thousand dollars. The development of two lines meant doubling the equipment units and the size of the initial investment capital. However, by using two conveyors, each could be configured to produce specific types of products, allowing production to become more flexible. In addition, increased productivity, employee satisfaction, and reduced safety and quality costs can offset the cost of designing an additional line.

Thus, by adhering to the simple rule that the speed of any manual operation should not be less than 50 seconds, losses can be avoided. When designing lean manufacturing processes, it is necessary to use the 3P (Production Preparation Process) method 1 and conduct a thorough analysis of takt time.

1 A method of designing a lean manufacturing process for a new product or fundamentally redesigning the manufacturing process for an existing process when there is a significant change in product design or demand. For more information, see: Illustrated Glossary of lean manufacturing/ Ed. The Marchwinskis and John Shook: Trans. from English M.: Alpina Business Books: CBSD, Center for the Development of Business Skills, 2005. 123 p. Note ed.

Based on the article Job Miller, Know Your Takt Time
and books by James P. Womack, Daniel T. Jones Lean Manufacturing.
How to get rid of losses and achieve prosperity for your company.
M.: Alpina Business Books, 2004
prepared by V.A. Lutseva

Production is called continuous production, in which, in a steady state, all operations are simultaneously performed on an orderly moving set of similar products, except perhaps for a small number of them with not fully loaded workplaces.

Flow production in its most advanced form has a set of properties that correspond to the maximum extent to the principles of rational organization of production. The main such properties are the following.

Strict rhythm of product release. Rhythm of release - This is the number of products produced per unit of time. Rhythm- is the release of products with a constant rhythm over time.

Release stroke- This is a period of time through which one or the same number of products of a certain type are periodically produced.

There are options for continuous production, in which, in principle, there is no rhythm of production at the level of individual copies of products. Strict regularity of repetition of all flow operations - This property consists in the fact that all operations of continuous production of a certain type of product are repeated at strictly fixed intervals, creating the prerequisites for the rhythmic release of these products.

Specialization of each workplace in performing one operation for the manufacture of products of a certain type.

Strict proportionality in the duration of all operations of continuous production.

Strict continuity of movement of each product through all production line operations.

Straightforward production. The location of all workplaces in a strict sequence of technological operations of continuous production. However, in a number of cases, for certain reasons, it is not possible to achieve complete straightness in the arrangement of workplaces, and returns and loops occur in the movement of products.

Types of production lines.

Production line - This is a separate set of functionally interconnected workplaces at which the continuous production of products of one or more types is carried out.

According to the nomenclature of products assigned to submarines, the following are distinguished:

Single-subject PL, each of which is specialized in the production of one type of product

Multi-subject PL, at each of which several types of products are manufactured simultaneously or sequentially, similar in design or technology for their processing or assembly.

Based on the nature of the products passing through all operations of the production process, they are distinguished:

Continuous production lines, on which the products are continuous, i.e. without inter-operational follow-ups, they go through all operations of their processing or assembly

Discontinuous production lines, of which there are inter-operational beds, i.e. discontinuity in processing or assembly of products.

Based on the nature of the tact, they are distinguished:

Production lines with regulated cycles, in which the beat is set forcibly using conveyors, light or sound alarms.

Production lines with free takt, in which the execution of operations and the transfer of products from one operation to another can be carried out with slight deviations from the established design cycle.

Depending on the order of processing of products on them various types are divided into:

Multi-subject production lines with sequential batch alternation of batches of products of various types, in which each type of product is exclusively processed for a certain period, and the processing of different types of products is carried out in successively alternating batches. On lines of this type, it is necessary to rationally organize the transition from the production of products of one type to the production of another:

At the same time, the assembly of new types of products stops at all workstations of the production line. The advantage is the absence of loss of working time, however, this requires the creation at each workplace of a backlog of products of each type that are in the stage of readiness that corresponds to the operation performed at this workplace.

products of a new type are launched onto the production line until the end of the assembly of a batch of products of the previous type, and on the production line during the transition period, the maximum of two possible cycles is set for the old and new types of products. However, during the transition period, downtime of workers is possible at those workplaces where products are assembled with a lower required cycle than the one currently installed.

Group production lines, which are characterized by the simultaneous processing of batches of several types of products on the production line.

GOST 14.004-83

Group T00

INTERSTATE STANDARD

TECHNOLOGICAL PREPARATION OF PRODUCTION

Terms and definitions of basic concepts

Technological preparation of production. Terms and definitions of basic concepts

ISS 01.040.03
01.100.50
OKSTU 0003

Date of introduction 1983-07-01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR State Committee for Standards

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated 02/09/83 N 714

3. This standard corresponds to ST SEV 2521-80 in terms of paragraphs 1-3, 8-11, 13, 15, 20-24, 28-36, 40, 43, 50

4. INSTEAD GOST 14.004-74

5. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

6. EDITION (February 2009) with Amendments No. 1, 2, approved in February 1987, August 1988 (IUS 5-87, 12-88)


This standard establishes mechanical engineering and instrument making products used in science, technology and production *.
________________
* Including repair.


The terms established by the standard are mandatory for use in all types of documentation, scientific, technical, educational and reference literature.

Clauses 1-3, 8-11, 13, 15, 20-24, 28-36, 40, 43, 50 of this standard correspond to ST SEV 2521-80.

This standard must be used in conjunction with GOST 3.1109, GOST 23004 and GOST 27782.

There is one standardized term for each concept. The use of terms that are synonyms of a standardized term is prohibited. Synonyms that are unacceptable for use are given as a reference and are designated “NDP”.

For individual standardized terms, the standard provides short forms for reference, which are allowed to be used in cases that exclude the possibility of their different interpretation.

Established definitions can, if necessary, be changed in the form of presentation, without violating the boundaries of concepts.

The standard provides alphabetical index terms contained therein and an appendix containing terms and definitions of the scope of work and characteristics of the management of the Chamber of Commerce and Industry.

Standardized terms are in bold font and are short form- light, and unacceptable synonyms - italic.

(Changed edition, Amendment No. 2).

TERMS AND DEFINITIONS OF BASIC CONCEPTS OF TECHNOLOGICAL PREPARATION OF PRODUCTION

TERMS AND DEFINITIONS OF BASIC CONCEPTS OF TECHNOLOGICAL PREPARATION OF PRODUCTION

ALPHABETIC INDEX OF TERMS

(Changed edition, Amendment No. 1).

APPENDIX (reference). TERMS AND DEFINITIONS OF WORK AND CHARACTERISTICS OF CCI MANAGEMENT

APPLICATION
Information

Electronic document text
prepared by Kodeks JSC and verified against:
official publication
Technological preparation system
production:
Collection of national standards. -
M.: Standartinform, 2009

For conditions of serial and small-scale production, the annual product production program is not carried out all at once, but is divided into batches. Lot of parts– this is the number of parts simultaneously launched into production. The breakdown into batches is explained by the fact that the customer often does not need the entire annual program at once, but requires a uniform supply of ordered products. Another factor is the reduction of work in progress: if, for example, 1000 gearboxes need to be assembled, then the production of 1000 No. 1 shafts will not allow the assembly of a single gearbox until at least one set is available.

The lot size of the parts affects:

1. On process performance and him cost price due to the share of time of preparatory and final work (T p.z.) per product

t pcs. = t pcs + T p.z. / n , (8.1)

Where t pcs. - piece-calculation time for a technological operation; t pcs – piece time for a technological operation; n– batch size of parts. The larger the batch size, the shorter the unit costing time for the technological operation.

Preparatory-final time (T p.z.) is the time for performing work to prepare for the processing of parts at the workplace. This time includes:

1. time to receive a task from the site foreman ( operating card with a sketch of the part and a description of the processing sequence);

2. time to familiarize yourself with the task;

3. time to obtain the necessary cutting and measuring tools, technological equipment (for example, a three-jaw self-centering or four-jaw non-self-centering chuck, a drill chuck, a rigid or rotating center, a fixed or movable rest, a collet chuck with a set of collets, etc.) in the tool room pantry;

4. time to deliver the required workpieces to the workplace (in case of non-centralized delivery of workpieces);

5. time to install the required devices on the machine and align them;

6. time to install the required cutting tools on the machine, adjusting to the required dimensions when processing two to three test parts (when processing a batch of parts);

7. time for delivery of processed parts;

8. time to clean the machine from chips;

9. time to remove fixtures and cutting tools from the machine (if they will not be used in the next work shift);

10. time to hand over fixtures, cutting and measuring tools (which will not be used in the next work shift) to the tool storeroom.

Typically, the preparatory and final time ranges from 10 to 40 minutes, depending on the accuracy and complexity of processing, the complexity of aligning fixtures and adjusting to dimensions.

2. For the size of the workshop: The larger the batch, the more space required for storage.

3. To the cost of production through unfinished production: The larger the batch, the larger the work in progress, the higher the cost of production. The higher the cost of materials and semi-finished products, the greater the impact of work in progress on production costs.

The batch size of parts is calculated using the formula

n = N´ f/F , (8.2)

Where n– batch size of parts, pcs.; N– annual production program for all parts of all groups, pcs.; F– number of working days in a year; f– the number of days of stock for storing parts before assembly.

Thus, N/F– daily graduation program, pcs. Number of days of stock to store parts before assembly f = 2…12. The larger the size of the part (more storage space is required), the more expensive the material and manufacturing (more money is required, more loans are required), the lower the number of days of stock for storing parts before assembly is set ( f = 2..5). On practice f = 0.5...60 days.

For continuous production, the starting cycle and release cycle are characteristic.

t h =F d m/N zap, (8.3)

Where t z – start stroke, F d m– actual equipment time fund for the corresponding work shift m, N zap – program for launching blanks.

The release cycle is determined similarly

t V =F d m/N issue, (8.4)

Where N vyp – part production program.

Due to the inevitable occurrence of defects (from 0.05% to 3%), the launch program must be larger than the release program by the corresponding proportion.

In mechanical engineering there are three types of production: mass, serial and individual and two working methods: in-line and non-in-line.

Mass production characterized by a narrow range and large volume of output of products continuously manufactured over a long period of time. The main feature of mass production is not only the number of products produced, but also the performance of one constantly repeating operation assigned to them at most workplaces.

The production program in mass production makes it possible to narrowly specialize jobs and arrange equipment along the technological process in the form of production lines. The duration of operations at all workplaces is the same or a multiple of time and corresponds to the specified productivity.

Release cycle is the time interval through which products are periodically produced. It significantly influences the construction of the technological process, since it is necessary to bring the time of each operation to a time equal to or a multiple of the cycle, which is achieved by appropriately dividing the technological process into operations or duplicating equipment to obtain the required productivity.

To avoid interruptions in the operation of the production line, interoperational stocks (backlogs) of blanks or parts are provided at workplaces. Backlogs ensure continuity of production in the event of an unforeseen shutdown of individual equipment.

The flow organization of production ensures a significant reduction in the technological cycle, interoperational backlogs, backlogs and work in progress, the possibility of using high-performance equipment and a sharp reduction in labor intensity and cost of products, ease of planning and production management, the possibility complex automation production processes. With flow methods of work, working capital is reduced and the turnover of funds invested in production increases significantly.

Mass production characterized by a limited range of products manufactured in periodically repeating batches and a large production volume.

In large-scale production, special-purpose equipment and modular machines are widely used. The equipment is located not by type of machine, but by the items being manufactured and, in some cases, in accordance with the technological process being performed.

Medium production production occupies an intermediate position between large- and small-scale production. The batch size in mass production is influenced by the annual production of products, the duration of the processing process and the setup of technological equipment. In small-scale production, the batch size is usually several units, in medium-scale production - several dozen, in large-scale production - several hundred parts. In electrical engineering and apparatus engineering, the word “series” has two meanings that should be distinguished: a number of machines of increasing power for the same purpose and the number of simultaneously launched into production of the same type of machines or devices. Small-scale production according to your own technological features approaches unity.

Single production characterized by a wide range of manufactured products and a small volume of their output. A characteristic feature of unit production is the implementation of various operations at workplaces. Unit production products are machines and devices that are manufactured according to individual orders that provide for the fulfillment of special requirements. These also include prototypes.

In single production, electrical machines and devices of a wide range are produced in relatively small quantities and often in a single copy, so it must be universal and flexible to perform various tasks. In single production, quickly adjustable equipment is used, which allows you to switch from the manufacture of one product to another with minimal loss of time. Such equipment includes computer-controlled machines, automated warehouses, computer-controlled, flexible automated cells, sections, etc.

Universal equipment in single production is used only in enterprises built earlier.

Some technological methods that arose in mass production are used not only in serial, but also in individual production. This is facilitated by the unification and standardization of products and specialization of production.

Assembly of electrical machines and devices is the final technological process in which individual parts and Assembly units combined into a finished product. Main organizational forms the assemblies are stationary and movable.

For stationary assembly the product is completely assembled at one workplace. All parts and assemblies required for assembly are supplied to workplace. This assembly is used in single and serial production and is carried out in a concentrated or differentiated manner. With the concentrated method, the assembly process is not divided into operations and the entire assembly (from start to finish) is performed by a worker or team, but with a differentiated method, the assembly process is divided into operations, each of which is performed by a worker or team.

For moving assembly the product moves from one workplace to another. Workstations are equipped with the necessary assembly tools and devices; on each of them, one operation is performed. The movable form of assembly is used in large-scale and mass production and is carried out only in a differentiated way. This form of assembly is more progressive because it allows assemblers to specialize in certain operations, resulting in increased labor productivity.

During the production process, the assembly object must sequentially move from one workplace to another along the flow (such movement of the assembled product is usually carried out by conveyors). Continuity of the process during continuous assembly is achieved due to the equality or multiple of the execution time of operations at all workstations of the assembly line, i.e., the duration of any assembly operation on the assembly line must be equal to or a multiple of the release cycle.

The assembly cycle on the conveyor is the planning beginning for organizing the work of not only the assembly department, but also all the procurement and auxiliary workshops of the plant.

With a wide range and small quantities of manufactured products Frequent reconfigurations of equipment are required, which reduce its productivity. To reduce the labor intensity of manufactured products in last years based on automated equipment and electronics, flexible automated production systems(GAPS), allowing the production of individual parts and products of various designs without reconfiguring equipment. The number of products produced at GAPS is set during its development.

Depending on the designs and overall dimensions of electrical machines and devices, different assembly processes . The choice of technological assembly process, the order of operations and equipment is determined by the design, volume of production and the degree of their unification, as well as the specific conditions existing at the plant.

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