1. An assembly line with 17 tasks is to be balanced. The longest task is 2.4 min
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Question
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 worksheets 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? and (2) 15 minutes?
2) A manager wants to assign tasks to workstations as efficiently as possible and achieve an hourly output of four units. The department uses a working time of 56 minutes per hour. Assign the tasks shown in the accompanying precedence diagram (times are in minutes) to workstations using the following rules:
a. In order of most following tasks. Tiebreaker: greatest positional weight.
b. In order of greatest positional weight. Tie breaker: most following tasks.
c. What is the efficiency?
3. As part of a major plant renovation project, the industrial engineering department has been asked to balance a revised assembly operation to achieve an output of 240 units per eight-hour day. Task times and precedence relationships are as follows:
Do each of the following:
a. Draw the precedence diagram.
b. Determine the minimum cycle time, the maximum cycle time, and the calculated cycle time.
c. Determine the minimum number of stations needed.
(minutes) Immediate
Predecessor a 0.2 - b 0.4 a c 0.2 b d 0.4 - e 1.2 d f 1.2 c g 1.0 e, f
Explanation / Answer
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 worksheets 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? and (2) 15 minutes?
Solution :-
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:
@2.4 min : 450 / 2.4 = 187.5 units
@18 min : 450 /18 = 25 units
c. N = 187.5 ( 18 ) /450 = 7.5 which rounds to 8.
d. Output = OT/CT
So, CT = 450 /125 = 3.6 minutes per cycle.
e. Potential Output :
(1) CT = 9 min . : OT / CT = 450/9 = 50 units.
(2) CT = 15 min. : OT / CT = 450 / 15 = 30 units.
2) A manager wants to assign tasks to workstations as efficiently as possible and achieve an hourly output of four units. The department uses a working time of 56 minutes per hour. Assign the tasks shown in the accompanying precedence diagram (times are in minutes) to workstations using the following rules:
a. In order of most following tasks. Tiebreaker: greatest positional weight.
b. In order of greatest positional weight. Tie breaker: most following tasks.
c. What is the efficiency?
Solution :-
Desired output = 33.33 units per hour
Operating time = 60 minutes per hour
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