7. An assembly line is to be designed to operate 7 1/2 hours per day and supply a steady demand of 300 units per day. Here are the tasks and their performance times:
TASK PRECEDING PERFORMANCE TASK PRECEDING PERFORMANCE
TASKS TIME(SECONDS) TASKS TIME(SECONDS)
a 70 g d 60
b 40 h e 50
c 45 i f 15
d a 10 j g 25
e b 30 k h, i 20
f c 20 l j, k 25
a. Draw the precedence diagram.
b. What is the workstation cycle time?
c. What is the theoretical minimum number of workstations?
d. Assign tasks to workstations using the longest operating time.
e. What is the efficiency of your line balance?
f. Suppose demand increases by 10 percent. How would you react to this? Assume that you can operate only 7 1/2 hours per day.
11. The flow of materials through eight departments is shown in the table below. Even though the table shows flows into and out of the different departments, assume that the direction of flow is not important. In addition, assume that the cost of moving material depends only on the distance moved.
1 2 3 4 5 6 7 8
2 15 25 4
3 5 40 5
4 5 10
5 1 20 30
7 3 10
a. Help construct a schematic layout where the departments are arranged on a 2 ? 4 grid with each cell representing a 10 ? 10-meter square area.
b. Evaluate your layout using a distance-times-flow measure. Assume that distance is measured rectilinearly (in this case, departments that are directly adjacent are 10 meters apart and those that are diagonal to one another are 20 meters apart).
The solution discusses questions regarding to an assembly line being designed.