Consider the following four-step assembly operation with quality problems. All r
ID: 374697 • Letter: C
Question
Consider the following four-step assembly operation with quality problems. All resources are staffed by one employee.
The first resource has a processing time of 5 minutes per unit.
The second resource has a processing time of 6 minutes per unit.
The third resource has a processing time of 3 minutes per unit. With a 30 percent probability, the flow unit coming out of the third resource has to be reworked. In that case, the operations at the first, second, and third resources are repeated. You can assume that (a) rework always succeeds and (b) the processing times for units in rework are same as for regular units.
The fourth resource has a processing time of 4 minutes per unit.
What is the capacity of the process?
Please, can you give the answer in two decimal places? This is the second time I post the question. I was given 10 as the answer which was wrong.
Explanation / Answer
Since there is a 30% probability that the item will be reworked , 0.30 out of every item are reprocessed in first , second and third resource.
Therefore effective reprocessing capacity of every resource ( first/second / third) will be 1.3 times of given capacity because of the Reprocessing factor.
Therefore,
Effective Processing time of first resource = 1.3 x 5 = 6.5 minutes / unit
Effective processing time of second resource = 1.3 x 6 = 7.8 minutes/ unit
Effective Processing time of the third resource = 1.3 x 3 = 3.9 minutes / unit
Processing time of 4th resource ( remains unchanged because of no reprocessing)= 4 minutes
It is always the bottleneck resource which decides capacity of a process. Bottleneck resource will be the one which will have highest processing time.
In this case, second resource has the highest processing time and hence acts as bottleneck resource.
Therefore Capacity of the process involves 7.8 minutes of processing per unit.
Therefore, its processing capacity i.e. number of units it can process in an hour = 60/7.8 = 7.69 ( rounded to 2 decimal places )
CAPACITY OF THE PROCESS IS 7.69 UNITS PER HOUR
CAPACITY OF THE PROCESS IS 7.69 UNITS PER HOUR
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