Consider the following threestep process with rework The fir

Consider the following three-step process with rework. The first resource takes 5 minutes per unit, the second 3 minutes per unit, and the third 2 minutes per unit. After the third step, 60% of all units have to be reworked. For that, they have to revisit the second and third resources. In that case, the processing times are the same as the first pass. Moreover, rework also always fixes the problem. Assume each resource has one worker.

a. Where in the process is the bottleneck?
b. What is the capacity of the process?

Solution

Following is to be noted:

Effective processing time per unit   of any resource = Normal processing time ( 1 + rework percentage/100)

Accordingly ,

Effective processing time per unit for first resource = 5 minutes ( remarks: There is no rework at first resource )

Effective processing time per unit for 2^nd resource = 3 x ( 1 + 60/100 ) = 3x 1.6 = 4.8 minutes

Effective processing time per unit for 3^rd resource = 2 x ( 1 + 60/100 ) = 2 x 1.6 = 3.2 minutes

Since it effectively takes maximum time ( i.e. 5 minutes ) to process 1 unit at first resource level, bottleneck is at first resource level

Capacity of the process ( on per hour basis 0 = 60/ Capacity of the bottleneck resource per unit = 60/ 5 = 12 units

BOTTLENECK IS AT FIRST RESOURCE

CAPACITY OF THE PROCESS IS 12 UNITS PER HOUR