Question

Determine the processing sequence for the five jobs to be processed on the two work centers shown below using Johnson's Rule. What is the total throughput time. Show your work.

Job	Center1	Center2
A	6	7
B	10	9
C	12	8
D	5	11
E	13	4

Answer 1

"As per Johnson’s Rule, Select the job with the shortest operation time. If the shortest operation time is for center1, then schedule that job first. If It is for the center2, then schedule that job at the last. If there is a tie, prefer the job on center1. Eliminate the assigned job from further consideration."
Here,
E at centre 2 has the shortest operation time of 4, so it will be scheduled at last that is fifth.

D at centre 1 has the next shortest operation time of 5, so it will be scheduled at first.

A at centre 1 has the next shortest operation time of 6, so it will be scheduled at second.

C at centre 2 has the next shortest operation time of 8, so it will be scheduled at second last that is fourth.

Next shortest operation time is 9 of Job B at centre 2 , so it will be scheduled at third.

Processing sequence for the five jobs to be processed on the two work centers using Johnson's Rule is :
D-A-B-C-E

Total throughput time calculation
Centre 1 - Cumulative operation time
D : 5
A : 11 (5+6)
B : 21 (11+10)
C : 33 (21+12)
E : 46 (33+13)

Centre 2 - Cumulative operation time
D : 16 (11+5) For centre 2's first job we will add operation time of first centre as well. Then we will take Cumulative of centre 2 operation times.
A : 23 (16+7)
B : 32 (23+9)
C : 40 (32+8)
E : 44 (40+4)

So, total throughput time is 44 (maximum value)