Tact in production. In-line production: organizational and economic characteristics

Production characteristic

Working hours and time funds

Hours of operation include the number of working days per year, excluding weekends and public holidays, with two shifts per day, because an automated section is being developed. The full calendar annual fund of time shows the number of hours in a year 24363=8670h.

Excluding weekends and holidays, based on a five-day working week lasting 41 hours, we get the nominal time fund FN = 4320 hours.

We take into account equipment downtime for repairs, FD - the actual annual fund of equipment operation time for 2-shift operation.

PD = 3894 hours.

Determination of the release cycle

To justify the organization production process and determining the type of production, it is necessary to calculate the average production rate - and the average piece time - Tsh.sr. production of the product in the main operations.

The release cycle is determined by the formula:

(min/pcs) (3.3.1)

where Fd = 3894 hours;

Ng = 20000pcs - annual program for the production of parts;

fs = 3894 60/20000 = 11.7 min/pc

Determining the type of production

The type of production can be determined by the numerical value of the operation fixing coefficient, the calculation of which is carried out in accordance with GOST 3.11.08-74. Approximately the type of production can be determined by the value of the coefficient - Kc

where Tsht.sr - the average piece time of manufacturing the product, is determined according to the data of the current technical process.

Tsht.av. = 71.43/17 = 4.2 min.

Kzo \u003d 11.6 / 4.2 \u003d 2.7

1< Кс?10 - крупносерийное производство

Analysis of the manufacturability of the design of the part "Drive shaft"

Manufacturability - a property of the product, according to which the design of the part must comply with the use of the most advanced processing or assembly methods in the manufacture.

Rational designs of machines that provide the necessary operational requirements cannot be created without taking into account the labor intensity and material consumption of their manufacture. Compliance of the design of machines with the requirements of labor intensity and material consumption determines the manufacturability of the design. In an objective assessment of the manufacturability of the design of machines, their parts and assemblies, a number of positive factors are taken into account that determine the manufacturability of the design.

In an objective assessment of the manufacturability of the design of machines, their parts and assemblies, a number of positive factors are taken into account that determine the manufacturability of the design. These include:

The optimal shape of the part, which ensures the manufacture of the workpiece with the smallest allowance and the smallest number of machined surfaces;

The smallest weight of the machine;

The smallest amount of material used in the construction of machines;

Interchangeability of parts and assemblies with the optimal value of tolerance fields;

Normalization (standardization) and unification of parts, assemblies and their individual design elements.

The basic requirements for the manufacturability of the design of machine building parts are set out in the literature.

Part designs must consist of standard and unified structural elements (QED) or be standard as a whole. Parts must be made from standard or unified blanks. The dimensions of the part must have optimal accuracy. Surface roughness must be optimal. The physicochemical and mechanical properties of the material of the part, its rigidity, shape, dimensions must comply with the requirements of the manufacturing technology (including the processes of finishing and hardening treatment, applying anti-corrosion coatings, etc.), as well as storage and transportation.

The base surface of the part must have optimal indicators of accuracy and surface roughness, which provide the required accuracy of installation, processing and control.

Blanks for the manufacture of parts must be obtained in a rational way, taking into account the material, the given output volume and the type of production. The method of manufacturing parts should allow the simultaneous production of several parts. The design of the part must ensure the possibility of using standard and standard technological processes for its manufacture.

We will test the manufacturability of the “Drive shaft” part for manufacturability in accordance with Guidelines.

Requirements for the qualification of workers are low.

Control can be active or passive.

Passive control is carried out after the end of work, and it aims to register a marriage.

Active control is performed during the processing of the workpiece and its purpose is to prevent rejects, for example, when a given size is reached, the machine turns off.

In large scale and mass production organize production lines: machines are installed in the course of the technological process, the workpiece moves from machine to machine, either synchronously with the release cycle (on-line production), or without fulfilling the principle of synchronization of the operation.

Release stroke

F d - the actual annual fund of equipment operation in 1 shift (F d "2015).

n is the number of work shifts.

N is the annual output of products.

60 - conversion factor, hours per minute.

The release cycle is the time between the release or launch of two adjacent units of production.

In CS and MC production, synchronization of operations is often used, i.e. their distance is equal to or a multiple of the beat.

A production line with non-synchronized operations is called a variable-flow line; in this case, a backlog method is provided for a separate operation.

In SS production, the most appropriate is the group form of the organization of the technological process.

Its essence lies in the fact that subject-closed areas are created for the manufacture of a group of technologically and structurally similar products. For example, a section of shafts, pulleys.

Figure 4 - Structure of the CCI

aimed at the development, preparation for production and release of a new type of product.

Scientific PP aims to conduct research on the possibility of using advanced achievements of natural and applied sciences in a new product.

Design software aims to prepare design documentation for a new product (assembly, installation, instructions). The checkpoint is being implemented in the department of the chief designer.

CCI is a set of measures aimed at preparing for the release of a new product.

Initial information - design documentation and production volume.

The first function is testing for manufacturability, its goal is the technologist's confidence in the possibility of manufacturing a product under given production conditions.

Design and manufacture of service stations: tooling design bureau and tool production are under the influence of the chief technologist.

Management of the Chamber of Commerce. Her functions.

Organization of PP - preparation of materials, components.

4 Production and technological processes and their structure.

To manufacture a machine capable of fulfilling its official purpose, it is necessary to perform a set of works to convert the source material into parts, assembly units and products as a whole.

The whole range of these activities is a complex process.

According to GOST 14003-83, the production process is a set of actions of people and tools necessary for this enterprise, for the manufacture or repair of products.

The production process consists of technological processes: procurement (casting, forging, etc.); machining, heat treatment, transportation, etc.

The technological process is a part of the production process that contains purposeful actions to change or determine the state of the object of labor.

Definition is a control operation.

Figure 5 - The structure of the technological process.

Technological operations are a complete part of the technological process performed at one workplace.

In the technological process, the operations are numbered through 5.

For example: 5.10… or 05.10…

Installation - a part of the technological operation, performed with the unchanged fixing of the workpiece being processed or the assembled assembly unit.

AT technological documentation installations are designated by the letters A, B, etc.

Figure 6 - Scheme of designation of installations.

Position - a fixed position occupied by a permanently fixed workpiece together with a fixture relative to a cutting tool or a fixed piece of equipment to perform a certain part of an operation. Positions in the technological documentation are indicated by Roman numerals.

The concept of a position is present in operations performed on multi-spindle machines, as well as on machines such as machining centers.

For example, positions for a multi-spindle vertical machine.

This use of equipment is called dual index operation.

The operation consists of two setups and 8 positions.

On machines such as machining centers, body workpieces are often processed using rotary tables. This makes it possible to process the workpiece from different sides with one constant fixing. The processing of each side will represent a separate item.

Figure 9 - Processing 3 faces on the machine.

Technological transition- this is a completed part of the technological operation, characterized by the constancy of the tool and surfaces used under constant technological conditions.

Auxiliary transition- this is a completed part of a technological operation, consisting of human (or equipment) actions that are not accompanied by a change in the shape, size or surface roughness, but necessary to perform a technological transition. For example, install the workpiece, remove.

working stroke- the completed part of the technological transition, consisting of a single movement of the tool relative to the surface being machined, accompanied by a change in the shape, size, roughness and other properties of the workpieces.

Engineering technology- a science that studies and establishes the patterns of the flow of processing processes and parameters, the impact on which most effectively affects the intensification of processing processes and increase their accuracy. The subject of study in engineering technology is the manufacture of products of a given quality in the quantity established by the production program, at the lowest cost of materials and the minimum cost.

Detail- this is an integral part of the product, made of a homogeneous material without the use of assembly operations. A characteristic feature of the part is the absence of detachable and one-piece connections in it. A part is the primary assembly element of every machine.

assembly unit- this is a product connected from components assembled separately from the rest of the elements of the product. As part of assembly unit both individual parts and components of lower orders can act.

Manufacturing process is a set of interrelated actions, as a result of which raw materials and semi-finished products are converted into finished products. In concept manufacturing process includes:

In engineering, there are three type of production: massive, serial and singular.

AT mass in production, products are manufactured continuously, in large quantities and for a long time (up to several years). AT serial- batches (series) of products that are regularly repeated at certain intervals. AT single- products are made in small quantities and, often, individually.

criterion, which determines the type of production, is not the number of manufactured products, but the assignment to the workplace of one or more technological operations(so-called. coefficient of fixing technological operations k ).

This is the ratio of the number of all technological operations performed or to be performed to the number of jobs.

So, for mass production, it is characteristic that most jobs are assigned only one constantly recurring operation, for serial production - several periodically repetitive operations, for a single one - a wide variety of non-repeating operations.

Another distinguishing feature of production types is the release cycle.

The release cycle is determined by the formula:

where F E- annual, effective time fund of the workplace, section or workshop, h

P- annual production program for the release of a workplace, section or workshop, pcs.

AT- the number of days off in a year;
P p is the number of holidays in a year;
t p days - the duration of the working day, hour;
n cm - the number of shifts.

Plant production program- this is the annual number of manufactured products expressed in labor intensity:

where P 1 ,P 2 and P n- production programs for products, man-hour.

Production program of the shipyard (SRZ)

NOTE: The symbol XXXX or XXXX in the table refers to any number of man-hours. Nomenclature - the annual number of manufactured products, expressed in items.

Shipyard nomenclature

Release cycle calculation. Determining the type of production. Characteristics of a given type of production

The dependence of the type of production on the volume of production of parts is shown in Table 1.1.

With a part weight of 1.5 kg and N=10,000 parts, medium-scale production is selected.

Table 1.1 - Characteristics of the type of production

Serial production is characterized by a limited range of manufactured parts manufactured in periodically repeating batches and a relatively small volume of output than in single production.

The main technological features of mass production:

1. Assigning several operations to each workplace;

2. The use of universal equipment, special machines for individual operations;

3. Arrangement of equipment according to technological process, part type, or machine groups.

4. Wide application of spec. Fixtures and tools.

5. Compliance with the principle of interchangeability.

6. Average qualification of workers.

The value of the release cycle is calculated by the formula:

where F d - the actual annual fund of the operating time of the equipment, h / cm;

N - annual program for the production of parts, N=10,000 pcs

Next, you need to determine the actual fund of time. When determining the fund of operating time of equipment and workers, the following initial data for 2014 were adopted at a 40-hour working week, Fd = 1962 h / cm.

Then by formula (1.1)

The type of production depends on two factors, namely: on a given program and on the complexity of manufacturing a product. On the basis of a given program, the cycle of product release t B is calculated, and the labor intensity is determined by the average piece (piece-calculation) time T pcs for the operations of an existing production or similar technological process.

AT serial production the number of parts in a batch is determined by the following formula:

where a is the number of days for which it is necessary to have a stock of parts, for = 1;

F - number of working days in a year, F=253 days.

Analysis of the requirements for the accuracy and roughness of the machined surfaces of the part and a description of the accepted methods for ensuring them

The part "Intermediate shaft" has low requirements for the accuracy and roughness of the machined surfaces. Many surfaces are machined to the fourteenth grade of accuracy.

The part is technological, because:

1. Free tool access is provided to all surfaces.

2. The part has a small number of precise dimensions.

3. The workpiece is as close as possible to the shape and dimensions of the finished part.

4. The use of high-performance processing modes is allowed.

5. There are no very exact sizes, except: 6P9, 35k6, 30k6, 25k6, 20k6.

The part can be obtained by stamping, so the configuration of the outer contour does not cause difficulties in obtaining the workpiece.

In terms of machining, the part can be described as follows. The design of the part allows it to be processed for a pass, nothing interferes this species processing. There is free access of the tool to the processed surfaces. The part provides for the possibility of processing on CNC machines, also on universal machines, does not present difficulties in basing, which is due to the presence of planes and cylindrical surfaces.

It is concluded that, from the point of view of the accuracy and cleanliness of the machined surfaces, this part generally does not present significant technological difficulties.

Also, to determine the manufacturability of a part,

1. Accuracy factor, CT

where K PM - accuracy factor;

T SR - the average quality of the accuracy of the surfaces of the part.

where T i - quality of accuracy;

n i - the number of surfaces of the part with a given quality (table 1.2)

Table 1.2 - The number of surfaces of the part "Intermediate shaft" with a given quality

In this way

2. Coefficient of roughness, KSh

where K W - roughness coefficient,

Ra SR - average roughness.

where Ra i is the surface roughness parameter of the part;

m i - the number of surfaces of the part with the same roughness parameter (table 1.3).

Table 1.3 - The number of surfaces of the part "Intermediate shaft" with a given roughness class

In this way

The coefficients are compared with one. The closer the values ​​of the coefficients are to one, the more manufacturable the part is. From the above, we can conclude that the part is quite technologically advanced.

Sometimes in articles and trainings some basic production concepts are called differently. The source of the confusion seems to be the translations foreign literature people who do not have the appropriate education. And some "gurus" of production management carry these incorrect terms to the masses. Today we would like to understand concepts such as "production cycle" and "cycle of release" - with what they mean, how they are measured or calculated.

We have chosen these two concepts, as they are sometimes confused with each other. But, before moving on to strict definitions, we would like to make a reservation that we will only talk about those types of industries that are found in the furniture industry.

Consider the classical simplest sequence of parts passing through production chain in the manufacture of furniture bodies: cutting, edge banding, additive (drilling), commissioning (sorting according to orders), packaging of parts with the addition of fittings or assembling the body, shipping or warehousing.

Each operation from this process starts only after the previous operation is completed. Such a process is called sequential. And here we come to the definition of a cycle. In general, a cycle is a sequence of events, processes or phenomena that repeats in time. For production, this is a sequence of technological operations. The total time of such operations in a sequential manufacturing process is the cycle time or cycle time.

Often in the literature and even in the standards, a cycle is called not the sequence of events itself, but its duration. For example, say that the cycle is 36 hours. In our opinion, it is more correct to say that the duration (or time) of the cycle is 36 hours, the cycle lasts 36 hours. But we will not judge strictly, it is much more important that something completely different is not called a cycle.

Once again, the duration of the production cycle as a whole or part of it is called the calendar period of time during which this object of labor goes through all stages from the first operation (cutting) to shipment or delivery to the warehouse of the finished product (assembled body or packages of finished panels with fittings) .

The cycle can be depicted graphically in the form of a step diagram - a cyclogram. Figure 1 shows a cyclogram of the serial production process of a part, consisting of 5 operations, each of which lasts 10 minutes. Accordingly, the cycle time is 50 minutes.

It is important to note that the cyclogram can display the sequence of operations for processing both one part and the sequence of manufacturing the product as a whole. It all depends on the level of detail with which we consider the process. For example, we can take into account the total cabinet installation time, or we can decompose this process into separate components - the connection of the bottom and top with the side walls, the installation of the rear wall, the hanging of the facades. In this case, we can talk about the operating cycle. A separate cyclogram can be built for it, and then the overall production cycle will consist like a nesting doll - of internal mini-cycles.

Some novice furniture makers make the following mistake. Wanting to determine the productivity of future production and the cost of production, they time the operations for the manufacture of any product, sum up the time obtained and try to divide the duration of the shift of 480 minutes by the estimated cycle time. However, in real production, things are not so simple.

First, the parts are processed not one at a time, but in batches. Therefore, until all the parts from this batch are processed, the rest can lie in anticipation. These are the so-called batch breaks and their duration must be taken into account when determining the total processing time.

In addition, after finishing the processing of one part (or batch), the worker does not turn off the machine and does not leave. He starts processing the next part (or batch). Figure 2 shows an example of a cyclogram, which shows that as soon as a part is transferred to the next operation, the production of the next part (for the same or another product) immediately begins at this workplace. For clarity, the periods of processing of various parts are shown in different colors.

In Figure 2, all operations last exactly 10 minutes. The process of processing each part (product) is represented by a colored “ladder”, while the steps of the “ladder” of a different color are tightly “pressed” to each step of this ladder, since each next part is processed without delay.

But what happens if some operations are slower or faster than others? In figure 3, operation 2 lasts not 10, but 20 minutes. And no matter how hard we try to “compress” the multi-colored “stairs”, that is, the processing cycles of sequentially processed parts (products), they “rest” against each other with the longest steps. And between the other steps, there are gaps - these are breaks in inter-operational expectations.

These breaks are of two types. The next one after a long operation is quickly released and idle waiting for details. And the previous one is waiting for the release of the next machine. At the same time, at the previous operation, nothing prevents the processing of the following parts from continuing, but this creates an excess of heterogeneous workpieces before the slow operation and leads to an increase in the volume of work in progress.

For example, a part requires edging on only two longitudinal sides, but at the same time it has a very large number of holes in the filler operation. Therefore, the part that comes out of the edgebander has to wait until the drilling machine is free. If the edge banding machine continues to work, then soon mountains of workpieces will appear in front of the additive site.

The opposite situation is also possible - the edges are lined on all four sides of the part, moreover, with material of different thicknesses with rounded corners, and only a couple of holes need to be made on the additive. As a result, the drilling machine is released earlier and idles while waiting for the next parts to arrive.

If the processing of the next batch of parts requires equipment adjustment, then the time for this procedure must also be taken into account when calculating the cycle time. In some industries, setup times can last hours or even days. For furniture makers, this is usually a few minutes, and if CNC equipment is used, the changeover time can be practically reduced to zero.

And, finally, there are breaks between shifts, for cleaning, for lunch, smoke breaks, a night break. Since the production cycle in the furniture industry usually lasts several days, such interruptions will also affect its duration.

The cycle time for different processes is different. As a rule, the production of cases takes from 1 to 5 days (depending on the batch size), for complex products with a variety of technologies and materials (painting, drying, veneering, working with solid wood) it may take 2-3 weeks.

We have described the simplest sequential process above. However, if we turn to real experience furniture production, we will see that the finished product consists not only of the body, but also of facades, glassware, metal, decor. These parts are made in other areas and these processes can be performed in parallel in time. The total production time in this case is determined by the longest cycle. As a rule, this is the time for the manufacture of painted facades or solid wood parts.

In case we use the Just In Time (JIT) production principle, it is important to get all the parts from the parallel process by the time of packaging, so complex facades begin to be manufactured long before an order is sent to the shop for the production of simple ones. case manufacturing.

Let's go back to our sequential process of making cases. If the product design calls for panels with curved edges, the process becomes more complicated. The cutting parts go all together, but then some of the parts go to CNC machining centers, where figured parts are formed, which are transferred to edge banding machines for "curvilinear". A nesting operation can also be used, when non-rectangular parts are cut directly from full-size slabs. At the same time, in order to increase the useful output, a part of rectangular parts is sometimes added to the cutting maps, which are then returned to the stream for facing straight edges.

Thus, some of the operations in such a thread are performed sequentially, and some are performed in parallel. Such a process is called parallel-sequential (sometimes vice versa - serial-parallel). Calculate cycle time for this case more difficult - you have to take into account simultaneous processing and simple summation does not work here anymore. It is most convenient to carry out the calculation on the basis of the analysis of cyclograms of processes. In more complex cases, a network model of the process is built.

Let's return to the cyclogram in Figure 2. It is obvious that at the output of the production process every 10 minutes we get a finished part or product. This time is called the release stroke. This is the interval between the manufacture of this and the next part (kit, package, product). In the above example, the cycle coincides with the duration of each of the 5 operations.

If the operations differ in time, then the cycle is determined by the slowest of them. In Figure 3, the cycle is dictated by operation 2. That is, despite the fact that all operations except the second last 10 minutes, we can receive finished products only every 20 minutes.

Value reverse tact output is called rhythm. This is the number of parts produced per unit of time.

Speaking of tact and rhythm, you must always understand what units we are talking about - individual parts, batches, kits for one product, kits for one order.

A takt can also be called the time interval between the release of shift (daily) jobs. If we analyze the progress of a shift task in sections, then as a rule one can see that this volume of parts moves unevenly, stretching in space and sometimes mixing with parts from other applications. It is very important to achieve such a clear rhythm of production, so that on each day of the week it is clear in which area of ​​​​the shop the parts put into production on a certain day should be located.

Thus, we cannot give an unambiguous answer to the question of whether production is fast. At the exit, we can have a very short cycle - relatively speaking, each cabinet can leave the factory every minute. But at the same time, in production, the same cabinet can “freeze” up to several weeks. Or maybe a short cycle, that is, what we sawed in the morning is already shipped in the form of finished products in the evening. However, the number of products produced per day may be insignificant.

Strict definitions of tact, rhythm and cycle can be found in GOST 3.1109 82. However, it is important not to remember the definition of a particular term word for word, but to understand its meaning and role in the evaluation of the technological process.