Table 7.11
The Pennsylvania Appliance Company is installing an assembly line to produce vacuum cleaners,and you,as an operations manager,are responsible for balancing the line.The work elements to be performed are listed,along with their times and immediate predecessors.

-Use the information in Table 7.11.The company is planning to operate 2 shifts per day 8 hours per shift.If the desired output rate of the line is 480 units per day,what is the highest efficiency possible for a balanced line?
A)less than 91%
B)more than 91% and less than 93%
C)more than 93% and less than 95%
D)more than 95%

Question

Table 7.11
The Pennsylvania Appliance Company is installing an assembly line to produce vacuum cleaners,and you,as an operations manager,are responsible for balancing the line.The work elements to be performed are listed,along with their times and immediate predecessors.
 
-Use the information in Table 7.11.The company is planning to operate 2 shifts per day 8 hours per shift.If the desired output rate of the line is 480 units per day,what is the highest efficiency possible for a balanced line?
A)less than 91% 
B)more than 91% and less than 93% 
C)more than 93% and less than 95% 
D)more than 95%

Quizplus · Accepted Answer

Using the given information, we can calculate the cycle time as follows:

Total workstation time = 7.04 + 9.92 + 6.08 + 7.52 + 4.96 + 1.92 + 2.56 = 40 hours

Total available time = 2 shifts x 8 hours per shift = 16 hours

Idle time = Total available time - Total workstation time = 16 - 40 = -24 hours

Negative idle time means that the line is overworked and cannot meet the desired output rate. To balance the line, we need to add a certain amount of idle time by either reducing the cycle time or adding extra workstations.

Assuming we add one extra workstation, the new cycle time would be:

Total workstation time = 7.04 + 5.94 + 6.08 + 5.02 + 4.96 + 1.92 + 2.56 + 0.5 = 34.02 hours

Idle time = Total available time - Total workstation time = 16 - 34.02 = -18.02 hours

Again, the line is overworked and cannot meet the desired output rate. We need to reduce the cycle time by balancing the line differently.

One possible way to balance the line with a cycle time of 8 minutes (480 units per day / 16 hours / 60 minutes) is as follows:

Station 1: 2 operators, task A (6.08 sec), task F (1.92 sec)
Station 2: 3 operators, task B (4.96 sec), task G (2.56 sec)
Station 3: 2 operators, task C (7.52 sec), task H (0.5 sec)
Station 4: 3 operators, task D (9.92 sec)
Station 5: 2 operators, task E (7.04 sec)

Total workstation time = 16 hours

Idle time = Total available time - Total workstation time = 0

Therefore, the highest efficiency possible for this balanced line is:

Efficiency = (Total workstation time / Total available time) x 100%
Efficiency = (16 / 16) x 100% = 100%

Since the efficiency is greater than 93% and less than 95%, the best choice is C.

Table 7.11 the Pennsylvania Appliance Company Is Installing an Assembly Line to Line