Assembly Line Design

BADM 615
Assembly Line Design
Problems (Solutions)

Assembly Line Design Problems (Solutions)
The following tables give the tasks, task times, and predecessors that are to be performed on an assembly line. Consider the scenarios and answer the corresponding questions for each.
1. Scenario One:
Task
A
B
C
D
E
F
G
H

Seconds
20
7
20
22
15
10
16
8

Preceding Tasks
—
A
B
B
C
D
E, F
G

The workday is seven hours long; and the demand for completed products is 750 per day.
a. Find the takt time (workstation cycle time).

b. What is the theoretical minimum number of workstations?

c. Draw the precedence diagram.

C

E

20

15

A

B

G

H

20

7

16

8

D

F

22

10

1

BADM 615
Assembly Line Design
Problems (Solutions)

d. Balance the line.
Station

Candidate(s)

Choice
A

Work-Element
Time (seconds)
20

Cumulative
Time (seconds)
20

Idle Time
(seconds)
13.6

1

A, B
B

B

7

27

6.6

C, D, E, F

D

22

22

11.6

C, E, F

F

10

32

1.6

3

C, E

C

20

20

13.6

4

E

E

15

15

18.6

G

G

16

31

2.6

H

H

8

8

25.6

2

5

e. What is the efficiency of the line balance?

2. Scenario Two:
Task
A
B
C
D
E
F
G
H
I

Minutes
1
1
2
1
3
1
1
2
1

Preceding Tasks
—
A
B
B
C, D
A
F
G
E, H

a. Draw the precedence diagram.
C
2

B

E

1

3

D

A

1

I

1

1

F

G

H

1

1

2

2

BADM 615
Assembly Line Design
Problems (Solutions)

b. Given a takt time of four minutes, develop two alternative layouts for balancing.
Layout #1:
Station

Candidate(s)

Choice
A

Work-Element
Time (minutes)
1

Cumulative
Time (minutes)
1

Idle Time
(minutes)
3

1

A
B, F

B

1

2

2

F, C, D

F

1

3

1

C, D, G

C

2

2

2

D, G

D

1

3

1

3

G, E

E

3

3

1

4

G