Need help on D and F only. Thanks! You have just been assigned the job of settin
ID: 376210 • Letter: N
Question
Need help on D and F only. Thanks!
You have just been assigned the job of setting up an electric fan assembly line with the following tasks and precedence relationships:
Task Time (minutes) Description Predecessors
A 2.8 Assemble Frame None
B 2.1 Assemble motor housing None
C 1.1 Mount motor housing in frame A,B
D 0.5 Attatch Blade C
E 1.8 Assemble and attatch safety grill D
F 1 Test E
The assembly line will be running 8 hours per day and 5 days per week. The demand forecast is 500 items per week. Your goal is to minimize the number of workstations necessary to complete enough units to satisfy the demand forecast.
a) Draw the precedence diagram
b) What is the takt time (in minutes) that we need to produce the required number of units? (4.8 minutes)
c) What is the theoretical minimum number of workstations that you will need? (2)
d) Assign the tasks to the workstations to balance the line using the longest operating time rule (meaning the takt time you calculated above). ???????
e) What is the efficiency of the balanced line? Since you have a balanced line with workstations, the takt time will be equal to the maximum total time among your workstations. (64.58%)
An engineer finds an alternative way of assembling and attaching the safety grill. It would take a little longer and increase the task time of task E to 3 minutes, but it could be done right after the frame is assembled. Tasks B, C, and D could be done before or after the safety grill is attached. Task F must still be the last task in the production process.
f) Would you benefit from redesigning the production process and using the new method? Why? What is the efficiency of this line? Explain answer.
(Hint: The new line can be one of the following two ways. Pick one of them.)
A->E C>D>F B->C- DExplanation / Answer
As per LPT:
F.
Vs
the new one:
Each line in the new one is optimized and has 100% efficiency A->E and then to F with the parallel is the best option
Task Pre Time ES EF Critical LS LF Slack Takt Line remaining time Line remaining time Total A NA 2.8 0 2.8 yes 0 2.8 0 4.8 1 2 B NA 2.1 0 2.1 0.7 2.8 0.7 2 2.7 C A,B 1.1 2.8 3.9 yes 2.8 3.9 0 2 1.6 D C 0.5 3.9 4.4 yes 3.9 4.4 0 2 1.1 E D 1.8 4.4 6.2 yes 4.4 6.2 0 1 0.2 F E 1 6.2 7.2 yes 6.2 7.2 0 2 0.1 9.3 Efficiency 95.83% 97.92% 96.88%Related Questions
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