Consider a four-station line in which all stations consists of single machines.
ID: 360786 • Letter: C
Question
Consider a four-station line in which all stations consists of single machines. Station 2 has average processing times of 2 hours per job, while the remaining stations have average processing times of 1 hour per job. Answer the following, under the assumption that process times are deterministic (as in the best case).
a). What are rb and To for this line?
b). How do rb and To change if a second identical machine is added to station 2? What effects will this have on performance?
c). How do rb and To change if the machine at station 2 is speeded up to have average processing times of 1 hour? What effects will this have on performance?
d). How do rb and To change if a second, identical machine is added to station 1? What effects will this have on performance?
e). How do rb and To change if the machine at station 1 is speeded up to have average processing times of 1/2 hour? What effects will this have on performance? Do your results agree or disagree with the statement "An hour saved at a nonbottleneck is a mirage (i.e., of no value)"?
Explanation / Answer
A.
T0 = 3 × 1 + 2 = 5 hours
and rb = 0.5 jobs / hour
B.
T0 will remain unchanged, =5 hours
while rb will be 1 job/hour
Increasing the bottleneck rate in the best stations will increase the throughput at WIP level greater than the critical WIP which will also increase. So, the final throughput will be more.
For cycle time it will be lower. This means that the performance will become better.
C.
Now T0 and rb will be affected.
The value of this is 4, which is higher and the maximum throughput will be 1 job/hour.
So, similar to (b) there will be improvement of the overall performance as the throughput will increase and the cycle time will be reduced.
Hence the performance in (b) is better than of this case.
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