# Mass production

Автор работы: Пользователь скрыл имя, 15 Сентября 2013 в 02:30, курсовая работа

##### Описание

So in this course project the production line that produces vertical sleeve hole with gloss on one side have been designed. During designing we’ve calculated technical and economic parameters of the production line, built graphics that present the synchronization of operations and load of equipment, also the time limit graph have been made.
The production line, we’ve got include 10 operations, use 18 machines and refer to the unsynchronized production lines.

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Introduction

Mass production is the production of large amounts of standardized products, including and especially on production lines. The concepts of mass production are applied to various kinds of products, from fluids and particulates handled in bulk (such as food, fuel, chemicals, and mined minerals) to discrete solid parts (such as fasteners) to assemblies of such parts (such as household appliances andautomobiles).

Nowadays the main problems of mass production are:

1. Impossibility to load production line;
2. With the lack of mechanization and automation of labor, work in the production line is characterized by monotony, great intensity and turnover of workers;
3. Significant capital investments for the organization of mass production;
4. Reliability of the equipment is not very high;
5. Frequent changes of types of products, due to technological progress.

The object of the work is to design a production line that produces vertical sleeve hole with gloss on one side. So, the main tasks of the project are:

2. Calculate technical and economical parameters of the production line;
3. Build the graphics that shows the results of calculations.

1. Output data

According to the objective the production line should produce vertical sleeve hole and gloss on one side.

Table 1.1 - List of manufacturing operations and characterization of the equipment

№ of

operation

## Equipment

Equipment sign

Wholesale Price,

UAH

Engine power, kW

Dimensions mm

Occupied area, m2

1.

## Handling of enterance

2Н135

28675

4

2535×825

4,25

2.

Broach hole

7Б55У

149110

18,5

4070×1600

26,05

3

Turning

1И611П

166315

3

1790×670

8,83

4.

Mechanical milling cutter

6Р80

57350

3

1600×1875

14,3

5.

Boring holes Ø20

2Н125

22940

2,5

2350×785

3,59

6.

Locksmith treatment

Locksmith treatment

11470

-

1000×800

4,1

7.

Washing

Washing

17205

0,5

950×750

3,6

8.

Heat treatment

Heat treatment

34410

4

1020×950

6,2

9.

Internal grinding

3К227А

206460

4

2815×1900

24,07

10.

External grinding

3А-110В

177785

1.5

1600×1670

17,03

The minimum wage for the current period is 1147 UAH.

Table 1.2 - Duration of process operations

 Indicators # of operation Category of work Value The annual output (Nр), units./year. 57000 The complexity of operations (tшт i), min./unit 1 3 7,13 2 5 2,26 3 5 10,81 4 6 5,77 5 3 3,88 6 2 2,89 7 1 2,06 8 4 5,85 9 6 9,52 10 6 4,84 Net weight of item, kg/unit. 6,66 Consumption rate of metal, kg/unit. (НВМ) 5,661 Complexity of manufacturing the product norm – kg/unit 55,01

During determination of the rate of metal consumption we’ve used the coefficient 0,85. The complexity of manufacturing the product was got by summarizing of the values of the complexity of manufacturing operations.

2 Designing of a production line in machining

2.1 Features and benefits of the mass production

As it was said in the Introduction: mass production is the production of large amounts of standardized products, including and especially on production lines.

The economies of mass production come from several sources. The primary cause is a reduction of nonproductive effort of all types.  In mass production, each worker repeats one or a few related tasks that use the same tool to perform identical or near-identical operations on a stream of products. The exact tool and parts are always at hand, having been moved down the assembly line consecutively. The worker spends little or no time retrieving and/or preparing materials and tools, and so the time taken to manufacture a product using mass production is shorter than when using traditional methods.

The probability of human error and variation is also reduced, as tasks are predominantly carried out by machinery. A reduction in labour costs, as well as an increased rate of production, enables a company to produce a larger quantity of one product at a lower cost than using traditional, non-linear methods.

However, mass production is inflexible because it is difficult to alter a design or production process after a production line is implemented.

So in a nutshell, the advantages of mass production over traditional are following:

1. continuity of work;
2. the principle of parallelism;
3. easy to plan production process;
4. regular output;
5. reduce the time of production.

2.2 Calculation of the tact (τ) of the production line

The tact is the indicator of work of production line.

Tact is the time between release of two products on the production line.

The tact of the streaming line is defined by the formula:

τ = , (2.1)

Where:

Fdob - Day Fund-time (8h2) · 60 = 960 min., with 8-hour working day in two shifts;

BP - regulated time spent on maintenance of machine, take Bp = 60 min.;

Ndob - daily release program, units.

τ = (960 - 60) /227= 3,96 min. / unit.

The daily release program is calculated by the formula:

, (2.2)

Where:

Np - given year program production, units.;

nrd - the number of working days in a year (365-104-10)= 251 days

Ndob = 57000/251 = 227 units.

Calculation of the amount of equipment for each operation conducted by the formula:

, (2.3)

Where:

nri - estimated number of machines on and one-operations units.;

tшт - an artificial time and th operation, min.;

τ - tact of streaming line, min. / units.

nр1= 7,13 / 3,96 = 1,8 units.                    nпр1 =2 units

nр2= 2,26 / 3,96 = 0,57 units.                    nпр2 =1 unit.

nр3 = 10,81 / 3,96 = 2,73 units.               nпр3 =3 units

nр4 = 5,77/ 3,96 = 1,46 units.                  nпр4 =2 units

nр5 = 3,88/ 3,96 = 0,98 units.                    nпр5 =1 unit

nр6= 2,89 / 3,96 = 0,73 units.                  nпр6 =1 unit

nр7 = 2,06 / 3,96 = 0,52 units.                  nпр7 =1 unit

nр8 = 5,85/ 3,96 = 1,48 units.                    nпр8=2 units.

nр9= 9,52/ 3,96 =  2,4 units.                   nпр9=3 units.

nр10 = 4,84/ 3,96 = 1,22 units             nпр10=2 units.

Nri is rounded to the first or next higher integer - get adopted npri number of machines.

Loading equipment ηзi also define for each i-th operation by the formula:

, (2.4)

ηз1 =( 1,8/2) * 100% = 89,95 %

ηз2 =( 0,57/1) * 100% = 57%

ηз3 =( 2,73/3) * 100% = 90,9%

ηз4 =(1,46/2) * 100% =72,8%

ηз5 = (0,98/1) * 100% = 98 %

ηз6 = (0,73/1) * 100% = 73%

ηз7 = (0,52/1) * 100% = 52%

ηз8 = (1,48/2) * 100% = 73,8%

ηз9 = (2,4/3 )* 100% = 80%

ηз10 = (1,22/2) * 100% = 61%

Loading of equipment for specific operations should not exceed 85 - 90% for creating of the reserve of the equipment to ensure the smooth operation of the production line. If the calculations would be higher than 85 - 90%, we should increase the number of machines.

For effective work of the equipment at the production line the level of loading of the machine should exceed 60-70%

Table 2.1 - Calculation of equipment on the production line (A):

Operation

name

tштi, хв.

nрi,шт.

nпрi, шт.

ηзі, %

tштi/nпрi

Degree of sinhronization Сі

1

7,13

1,8

2

89,95

3,565

0,202

2

Broach

entrance

2,26

0,57

1

57

2,26

-0,238

3

Turning

10,81

2,73

3

90,9

3,603

0,215

4

Boring

entrance Ø20

5,77

1,46

2

72,8

2,885

-0,027

5

Locksmith

treatment

3,88

0,98

1

98

3,88

0,308

6

Washing

2,89

0,73

1

73

2,89

-0,026

7

Heat

treatment

2,06

0,52

1

52

2,06

-0,306

8

Internal

grinding

5,85

1,48

2

73,8

2,925

-0,014

9

External

grinding

9,52

2,40

3

80

3,173

0,07

10

## enterance

4,84

1,22

2

61

2,42

-0,184

Total

55,01

13,88

18

74,84

29,662

, (2.5)

where m - number of operations.

= 13,88/18 = 0,77

Degree of non synchronization of operations is calculated by the formula:

, (2.6)

where - working tact on i operation;

- Average working tact of streaming line.

Average tact of the production line is found according to the formula:

= 29,66/10 = 2,966

С1 = (3,565– 2,966)/ 2,966=0,202

С= (2,26- 2,966)/ 2,966= -0,238

С3а   =(3,603- 2,966)/ 2,966=0,215

С4   =(2,885- 2,966)/ 2,966= -0,027

С5   =(3,88- 2,966)/ 2,966= 0,308

С=(2,89- 2,966)/ 2,966= -0,026

С7 =(2,06- 2,966)/ 2,966= -0,306

С8 =(2,925-2,966)/ 2,966 = -0,014

С9 =(3,173- 2,966)/ 2,966 = 0,07

С10  =(2,42- 2,966)/ 2,966 = -0,184

On the basis of the results we’ve got, we can plot the following graphics:

Figure 2.1 - Graph of synchronization of the operations

According to the level of synchronization the type of production line is determined. Organization of work and choose of transport means depends from the type of the line.

If at all operations the degree of desynchronization does not exceed 10%, then this line is synchronized continuous-flow. If at least one of operations exceeds the specified value, then this line should be called  unsynchronized

2.4 Equipment Selection

Selection of equipment in practice carried out simultaneously with the design process. This often guided by existing warehouse equipment. When selecting equipment in the project consider the following:

. 1) the ability to install and machining parts on a machine. For this the size of the details and macine are compared. For drilling machine, such as the basic size is diameter - maximum diameter drilling. For lathe - the height of the centers and the distance between the centers. The radius of details may not exceed the height of the centers and the length of detail - the distance between the centers;

2) the cost of the machine, we must use equipment with less price.

Choosing of the tools usually have to hold pricelist wholesale prices for machine tools.

Table 2.2 - Statement of equipment on the production line:

 Operation Name Model of machine Overall dimensions of machine, mm Quantity of machines Price, UAH. Engine power, kW One item Total One machine Total 1 2Н135 2535×835 2 28675 57350 4 8 2 7Б55У 4070×1600 1 149110 149110 18,5 18,5 3 1И611П 1790×670 3 166315 498945 3 9 4 6Р80 1600×1875 2 57350 114700 3 6 5 2Н125 2350×785 1 22940 22940 2,2 2,2 6 Bench press 1000×800 1 11470 11470 7 Washing 950×750 1 17205 17205 0,5 0,5 8 Heatequip 1020×950 2 34410 68820 4 8 9 3К227А 2815×1900 3 206460 619380 4 12 10 3А110В 1600×1670 2 177785 355570 1,5 3 Total 18 1915490 67,2

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