Ops Case Study

Pages: 12 (2025 words) Published: April 21, 2015
The manufacturing engineers at Toshiba have designed a prototype assembly line sheet for their new notebook. The manager has to make decisions to improve the line for better productivity over time, and reducing the cost. Furthermore, the company focuses on reducing number of components and assembly requirements.

1.)

What is the daily capacity of the assembly line designed by the engineers? Assume that the assembly line has a computer at every position when it is started at the beginning of the day.

Assumption: Every position in the assembly line has a computer at the beginning of the day.
The cycle time of the line: 120 seconds. (From Table B on page 11) Hours of operation of the line: 7.5 hours = 27,000 seconds.
Production Capacity= Total Operating Time / Cycle Time
Production Capacity = 27,000/120 = 225 units per day.

2.)

When it is running at the maximum capacity, what is the efficiency of the line relative to its use of labor? Assume that the supporter in not included in efficiency calculation.
When the line runs at maximum capacity, production capacity = 225. Number of Work Stations in the engineers’ designed assembly line = 6. Cycle time for the line = 120 seconds. (Refer Table B on page 11) Total task time = 893 seconds.

To calculate “efficiency”, in this case the software load time (310 seconds) is not included because there is no labor or supervision required for the task. Therefore, the total task time to calculate efficiency is:

893 – 310 = 583 seconds.
Efficiency = ∑ Task time / (Number of Work Stations * Cycle Time) Efficiency = 583 / (6*120) = 0.8097 = 80.97%
1

3.)

How should the line be redesigned to operate at the initial 250 units per day target, assuming that no over time will be used? What is the efficiency of your new design?

Required production capacity for the new line is 250 units per day, operating for 7.5 hours a day.
To design a new assembly line, a new cycle time is calculated for a higher required production capacity (250 units per day).
Total Operating Time of the Assembly Line = 7.5 hours = 27,000 seconds. Required Production Capacity = 250 units per day.
Cycle Time = Total Operating Time / Production Capacity
Cycle Time = 27000 / 250 = 108 seconds.
The precedence diagram is followed to assign order of tasks at various work stations. For precedence diagram, Figure 3.1 (Designed according to Table A, refer page 11).

Figure 3.1
Criteria used to balance the assembly line with the following order of preferences: 1. Assign the task with the largest number of following tasks. 2. Assign the task with the largest task time.
3. Task 15-Software Load is not assigned a work station because of zero labor. 2

Remaining Time

Work Station

(seconds)

(seconds)

1

--

--

108

1, 3

3

24

84

1, 4

4

36

48

5, 6, 7, 8 , 9

9

29

19

--

--

--

108

1, 5, 6, 7, 8, 10

10

26

82

1, 5, 6, 7, 8, 11

11

52

30

5, 12

12

7

23

5, 13

5

22

1

--

--

--

108

1, 6, 7, 8, 13

1

75

33

7, 13

7

32

1

--

--

--

108

2, 6, 8, 13

2

61

47

6, 8, 13

8

44

3

--

--

--

108

6, 13

6

39

69

13

13

5

64

14

14

11

53

15

310

6

16

60

108 - 60 = 48

--

7

17

60

108 - 60 = 48

--

2

3

4

5

Table 3.2

3

Efficiency = ∑ Task time / (Number of Work Stations * Cycle Time) Efficiency = 583 / (7*108) = 0.7712 = 77.12%
The Total Idle Time for the assembly line is 173 seconds

Since the efficiency of the new line is lower than that of the engineers’ design, a different approach is followed to setting the cycle time to minimum. From the data, the highest task time is for TASK 15 – Software Load (310 seconds). This task does not need a separate work station as there is no labour required for it. The next...