1a2 Plant Loyout Patterns

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Plant Layout


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Arc Welding Processes

Lesson Objectives

When you finish this lesson you will

understand:

Learning Activities

1. Read Handbook Pp1-16,

2. Look up Keywords

3. View Slides;

4. Read Notes,

5. Listen to lecture6. Do on-line

workbook

7. Do homework

Keywords:
http://we019.eng.ohio-state.edu/we300/w300t/we300.htmhttp://we019.eng.ohio-state.edu/wenc/wenc.cfm


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PLANT LAYOUT PATTERNS

Functional Layout

Group similar machines in centers which performsimilar functions.

Product Layout

Group machines in a line to make a certain product -

Assembly Line

Group Layout

(Variation of product layout) Machines are arranged so

that specific parts can be made in a group - then movedto next station (maybe even another plant).

Fixed Position Layout

The part is assembled in one location - machines andmaterials brought together.


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Group Machines in centers which perform similar functions


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Example: Movable Crane Manufacture

Outside Storage:

Incoming Plate and Supplies

Finished Product Awaiting Delivery


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Plate moves to a plasma arc cutting with water table

parts cut for telescoping armsup to 3 arms

parts cut for cab section

parts cut for carrier frames


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Plates sub arc welded into telescoping arms

note fixturing table

arms slide inside each other so must be straight

largest arm move to flame cut area and pivot hole cut SMAW hardfacing done around pivot hole


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All arms moved to GMAW station where stiffeners are welded on


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Arms inspected for straightness and weld workmanship

Arms assembled inside each other


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All parts assembled and painted


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Strain gage attached for lift proof testing


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Proof Testing performed on each unit before storage or delivery


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Advantages Disadvantages


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Best use of specialization of

machines & employees

Flexiblevariety of productsGeneral purpose machines

less costly

Ability to follow diverse paths

Less vulnerable to shutdowns

Machine breakdown less of

problem

Small batch product economy

Suitable for incentive pay

General purpose machines slower

Work routing, scheduling difficult

Material handling costs high

Material moves slowly

Partially finished inventory high

large storage space

Communication difficult

Some limit to size of parts


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Turn to the person sitting next to you and discuss (1 min.):


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Thousands of pounds per week to departmentsThousands

of poundsfrom

department

Sq.

ft. 2 3 4 5 6 7 8 9 10 11 12 13

1 3000 90 10

2 10000 75 15

3 15000 20 45 5 5

4 4000 13 25 9000 5 12 3

6 15000 35 10

7 6000 5

8 1200 3 5 5

9 8000 18 20

10 6000 33

11 10000 90

12 2000 10

13 8000

Load Path Method to Determine Plant Layout


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1

3000

2

10,0004

4000

3

15,000

8

1200

12

2000

5

9000

6

15,000

13

8000

11

10,000

9

8000

7

6000

10

6000

Direct:

Indirect:

90

16

15

90+

16+

15+

75

75+

20

20+

45

45+

5

5+

5

5+

13

13+

2

2+

5

5+

12

12+

3

3+

35

35+

10

10+

5

5+

3

3+

5

5+

5

5=

18

18+

20

20+

33

33+

90

90+

10

10= 49982

Minimum Load Path Arrangement


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1

3000

2

10,0004

4000

3

15,000

8

1200

12

2000

5

9000

6

15,000

13

8000

11

10,000

9

8000

7

6000

10

6000

1 2

3

4

5

6

7

8

910

11

12

13

Fit

Into

Existing

Building

Space


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Beside Total Weight there are other considerationswhich should not be overlooked

Bulk

Fragility

Cooperation between departments

Common services = air, electric power loading

Isolation of noisy or hazardous department


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Group machines in a line to make a certain product - Assembly line

A C B F G

A D E

Pallet from Group Layout


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Example: Wheel Rim Manufacture


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Coil handling equipmentslit coils are fed into blank cutter


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Blank cutter cuts pieces to exact length


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Flat strip blank is rolled into a cylinder


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Cylinder is flash welded


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Cylinder is flared on each end to expand to outside

wheel dimensions


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Wheel is roll formed though 3 or 4 successive expansions

to final wheel contour


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The spider which was stamped on another line is mated with

the wheel and GMAW together


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A C B F G

A D E

Pallet from Group Layout


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Best for products

made in large

quantities

Low cost per unitFast

Low material

handling costs

Low storage &

inventory

Simplified training of

new workers

Fewer personnel

Large initial investment

Vulnerable to stoppage

Inflexiblenew designs not

introducedParts must fit exactno

rework along line

Not suitable for incentive pay

Absenteeism hard to handle

All stations must take same

time


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Make a list of all the assembly elements

Time for each element (we will do a time study exercise later)

List which elements must precede the current task

Task

Element

Element

Time

(min)

Preceding

Elements

Element

Description

1 0.2 Na Place axel on car

2 .4 1 Place studs on axel

3 .7 1 Lubricate axel

4 .3 2 Place tire on wheel

5 .8 3 Place wheel on axel

6 .6 37 .2 4

8 .2 4

9 .8 5


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Optimize the time flow by assigning task elements to

work stations such that:

The time at every work station is close to the same

The correct sequence of operations is maintained

The number of work stations is reasonable

The required number of parts per hour exit the line

Example: Suppose to make a reasonable profit (we will do

a cost analysis exercise later) we need 65 cars exiting the

assembly line per hour.

car

min92.0

hr

cars65

hr

min60

The slowest work station will

dictate the entire line speed,

thus the slowest station must

take less time than 0,92 minutes


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1

2

3

4

5

6

7

8

9

10

11

12

13

14

0.2

0.7

1,3

0.9

0.4 0.3

0.2

2,4,7

0.9

0.8

5

0.8

0.6

0.3

6,10

0.9

0.5

0.3

11,13

0.8

0.8

9

0.8

0.2

0.1

0.6

8,12,

14

0.9

Precedence Diagram

Work Stations


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Turn to the person sitting next to you and discuss (1 min.):


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1a2 Plant Loyout Patterns

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