Solution of Johnson's Rule
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Solution of Johnson's Rule

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Solution of example by using the Johnson's Rule rules:

   Given table:

Job Work Centre 1
(Drill)
Work Centre 2
(Lathe)
A 5 2
B 3 6
C 8 4
D 10 7
E 7 12

Set the sequence that will minimise the total processing time for the five jobs:
Step 1    :    The job with the shortest processing time is A, in work centre 2(with a
                    time of 2 hours).
                    Because it is at the second centre, schedule A last.

        A

        Step 2     :    Job B has the next shortest time(3).
                              Because that time is the first work centre, we should schedule it first and
                              eliminate it from the consideration.

B       A

        Step 3     :    The next shortest time is Job C(4) on the second machine.
                               Therefore, place it at last.

B     C A

          Step 4    :     There is a tie(at 7) for the shortest remaining job.
                               We can place E, which was on the first work centre, first.
                               Then D is placed in the last sequencing position.

B E D C A

        The sequencial times are:

Job B E D C A
Work Centre 1 3 7 10 8 5
Work Centre 2 6 12 7 4 2


Figure9     The Time-phased flow of this job sequence is illustrated graphically as below :

jr.jpg (14973 bytes)

 

Simulation by using Johnson's Rule  Simulation on Johnson's Rule

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