Layout - exercise week 7 PDF

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LayoutCritical thinking Exercises Layout decisions affect a wide range of facilities, from factories, supermarkets, offices, department stores, and warehouses, to malls, parking lots and garages, and kitchens. Layout is also important in the design of some products such as the interiors of automobil...

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Layout Critical thinking Exercises 1. Layout decisions affect a wide range of facilities, from factories, supermarkets, offices, department stores, and warehouses, to malls, parking lots and garages, and kitchens. Layout is also important in the design of some products such as the interiors of automobiles and the arrangement of components inside computers and other electronic devices. Select three different items from this list, or other similar items, and explain for each what the four or five key considerations for layout design are. 2. How can technology impact layout decisions? 3. What is the goal of line balancing? What happens if a line is unbalanced?

Exercises 1. An assembly line with 17 tasks is to be balanced. The longest task is 2.4 minutes, and the total time for all tasks is 18 minutes. The line will operate for 450 minutes per day. a. What are the minimum and maximum cycle times? b. What range of output is theoretically possible for the line? c. What is the minimum number of workstations needed if the maximum output rate is to be sought? d. What cycle time will provide an output rate of 125 units per day? e. What output potential will result if the cycle time is (1) 9 minutes? (2) 15 minutes? 2. For the set of tasks given below, do the following: a. Develop the precedence diagram. b. Determine the minimum cycle time and then calculate the cycle time for a desired output of 500 units in a seven-hour day. Why might a manager use a cycle time of 50 seconds? c. Determine the minimum number of workstations for output of 500 units per day. d. Balance the line using the greatest positional weight heuristic. Break ties with the most following tasks heuristic. Use a cycle time of 50 seconds. Task A B C D

Task time (seconds) 45 11 9 50

Immediate predecessor A B -

E F G H I J

26 11 12 10 9 10

D E C C F,G,H I

3. Develop a process layout that will minimize the total distance traveled by patients at a medical clinic, using the following information on projected departmental visits by patients and distance between locations. Assume a distance of 35 feet between the reception area and each potential location. Use the format shown.

1. Department stores : The department stores have product of layout or Line Layout is the arrangement of machines in a line (not always straight).The sequence in which they would be used in the process of manufacture of the product. This type of layout is most appropriate in case of continuous type of industries where raw materials is fed at one end and taken out as finished product at the other end. For each type of product a separate line of production will have to be maintained Garages: Garages have process layouts. There is a functional division of work under this method. For example, lathes are fixed in one department and welding activities are carried in another department of the factory.

Factory: Ibis type of layout is undertaken for the manufacture of large parts and assemblies- In this case, material remains fixed or stationary at one place, men and equipment are taken to the site of material- This is suitable in case of ship building, locomotives and heavy machinery industries etc The key considerations about designing the layout are: • Time taken to complete: The choice is layout depends on the time constraint. In case of high production requirements, the traditional layout can be altered • Various resources and theft... 2 Technology has tremendous impact on process selection due to changes in computer related technology and associated capabilities. The level of automation continues to change in companies, thereby affecting layout decisions. For example, newer machinery is smaller; therefore, the size of the machinery affects the work area size and ultimately the layout of the facility.

3. Đoán đại:

The goal: 

The goal of line balancing is to obtain task groupings that represent approximately equal time requirements. This minimizes the idle time along the line and results in a high utilization of labor and equipment.



Lines that are perfectly balanced will have a smooth flow of work as activities along the line are synchronized to achieve maximum utilization of labor and equipment

What happens if a line is unbalanced: Idle time occurs if task times are not equal among workstations; some stations are capable of producing at higher rates than others. These “fast” stations will experience periodic waits for the output from slower stations or else be forced into idleness to avoid buildups of work between stations. Unbalanced lines are undesirable in terms of inefficient utilization of labor and equipment and because they may create morale problems at the slower stations for workers who must work continuously. A third cause of an inability to perfectly balance a line is that a required technological sequence may prohibit otherwise desirable task combinations. The main goal of line balancing is to achieve a set of task groupings at workstations in the line that have equal time requirements to attain high utilization of labor and equipment. Unbalanced

lines have bottlenecks at some workstations and idle time at others. The resulting output is lower than it would be if the line could be balanced.

Excersie: 1.

OT = 450 minutes a. Minimum cycle time = length of longest task, which is 2.4 minutes. Maximum cycle time =  task times = 18 minutes. b. Range of output:

450 =187 . 5 units 2.4 450 @18 min . : =25 units 18 @2 . 4 min . :

N= c.

Dx ∑ t 187. 5(18 ) =7 . 5 , which rounds to 8 = 450 OT

Output=

450 OT Solving for CT, CT= =3. 6 minutes per cycle CT 125

d. e. Potential output:

CT=9 min .: (1)

OT 450 = =50 units CT 9

CT=15 min .: (2) 2.

a.

450 =30 units 15

Solutions (continued)

CT= b.

OT 7(60 ) = = D 500 .84 minutes = 50.4 seconds (maximum cycle time)

Minimum cycle time = maximum task time = 45 seconds (results in 560 units of production)

N=

∑ t =193

c. d.

CT

50. 4

=3. 83 or 4 stations

Task A

Number of followers 6

*PW 106

B

5

61

C

4

50

D

4

106

E

3

56

F

2

30

G

2

31

H

2

29

I

1

19

J

0

10

*Positional weight CT = 50 seconds Work Station

Task

Task Time

Time Remaining

Feasible tasks Remaining

I

A

45

5

–

III

D

50

–

–

III

B

11

39

C, E

E

26

13

C, F

C

9

4

–

G

12

38

H, F

IV

V

F

11

27

H

H

10

17

I

I

9

8

–

J

10

40

–

Solutions (continued)

I=1− e.

193 =22 .8 % (50 )(5)

3. 16.

No. of trips (two way) 1–2

0

1–3

40

1–4

110

3–A, 5–B, 1–C, 4–D, 6–E, 2–F.

1–5

80

An equivalent solution is the reverse order:

1–6

50

2–F, 6–B, 4–C, 1–D, 5–E, 3–F.

2–3

0

2–4

50

2–5

40

2–6

120

3–4

10

3–5

250

3–6

10

4–5

40

4–6

90

5–6

20

A reasonable (intuitive) assignment is:

(Ignore Reception since all locations are the same distance from it.)...