19623402 scheduling and sequencing by johnson rule

8/13/2019 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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19623402 scheduling and sequencing by johnson rule

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