19623402 Scheduling and Sequencing by Johnson Rule
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Transcript of 19623402 Scheduling and Sequencing by Johnson Rule
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SCHEDULING & SEQUENCING
BY JOHNSONS RULE
GROUP MEMBERS
Rajendra kumar
Pratik
Puneet
Pintu
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DEFINATION
Establishing the timing of the use of
equipment, facilities and human activities in an
organization
Effective scheduling can produce:-
1) Cost savings
2) Increases in productivity
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Scheduling Difficulties
Variability in
Setup times
Processing times
Interruptions
Changes in the set of jobs
No method for identifying optimal schedule
Scheduling is not an exact science
Ongoing task for a manager
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Minimizing Scheduling Difficulties
Set realistic due dates
Focus on bottleneck operations
Consider lot dividing of large jobs
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SEQUENCING
JOHNSONSRULE
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SEQUENCING
Sequencing: Determine the order in which jobs
at a work center will be processed.
Workstation: An area where one person works,
usually with special equipment, on aspecialized job.
Priority rules: Simple hierarchy
used to select the order inwhich jobs will be processed.
Job time: Time needed for
setup and processing of a job.
Everything is
#1 Priority
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Priority Rules
FCFS - first come, first served
LTR - Least time required
LAR/LORLeast activity required/Fewestoperations required
EDD - earliest due date
CRS - critical ratio schedulingTop Priority
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JOHNSONS RULE
Technique for minimizing completion time for
a group of jobs to be processed on twomachines or at two work centers.
Minimizes total idle time
Several conditions must be satisfied
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Johnsons Rule Conditions
Job time must be known and constant Job times must be independent of
sequence
Jobs must follow same two-step sequence
Job priorities cannot be used
All units must be completed at the firstwork center before moving to second
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Example Of Johnsons Rule (Two Machines)
Job No. Time on M1 Time on M2 MC1 MC2 Sequence
St. Time End Time St. Time End Time
A 15 11 0 15 15 26 C
B 17 10 15 32 32 42 G
C 9 13 32 41 42 55 D
D 12 15 41 53 55 70 HE 14 14 53 67 70 84 E
F 12 10 67 79 84 94 I
G 12 14 79 91 94 108 JH 13 15 91 104 108 123 A
I 15 14 104 119 123 137 B
J 13 13 119 132 137 150 F
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Sequence MC1 MC2
(By Johnson's Rule) St. Time End Time St. Time End Time
C 0 9 9 22G 9 21 22 36
D 21 33 36 51
H 33 46 51 66E 46 60 66 80
I 60 75 80 94
J 75 88 94 107
A 88 103 107 118
B 103 120 120 130
F 120 132 132 140
So we can say that by
using Johnsons rule
of scheduling Time
saved in this case is :-
150 140 = 10
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Johnsons Rule for Three Machines
Condition:-Largest time on M2should be less
thanor equalto smallest time on M1or M2or
both.
If condition satisfied then we calculate:-
R1 = M1 + M2
R2 = M2 + M3
This whole can be understand by the help of
following example:-
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Job No. Time on M1 Time on M2 Time on M3 MC1 MC2
St. Time End Time St. Time End Time
A 16 12 11 0 16 16 28
B 15 11 12 16 31 31 42
C 12 10 13 31 43 43 53
D 13 9 15 43 56 56 65E 14 11 17 56 70 70 81
F 15 10 16 70 85 85 95
G 13 9 14 85 98 98 107H 12 12 17 98 110 110 122
TOTAL 84 115
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MC3
St. Time End Time
28 39
42 54
54 67
67 82
82 99
99 115
115 129
129 146
R1 R2 SEQUENCE
M1+M2 M2+M3 (BY JOHNSON'S RULE)
28 23 C
26 23 G
22 23 D
22 24 H
25 28 F
25 26 E
22 23 A24 29 B
Idle time on
Machine-2 is:-
122 84 = 38
Idle time on
machine-3 is:-
146 115 = 31
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SEQUENCE MC1 MC2 MC3
(BY JOHNSON'S RULE) St. Time End Time St. Time End Time St. Time End Time
C 0 12 12 22 22 35
G 12 25 25 34 35 49
D 25 38 38 47 49 64H 38 50 50 62 64 81
F 50 65 65 75 81 97
E 65 79 79 90 97 114
A 79 95 95 107 114 125
B 95 110 110 121 125 137
Total time saved by
Using Johnsons rule
Is:-
146 137 = 06
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CONCLUSION
Thus we can say that by using Johnsons rulewe can do more better sequencing of machines
and can save the time of production.
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