MELJUN CORTES - Operations Management 15th Lecture (SCHEDULING)

8/9/2019 MELJUN CORTES - Operations Management 15th Lecture (SCHEDULING)

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MELJUN CORTES,MBA,MPA,BSCS,ACSMELJUN CORTES,

MBA,MPA,BSCS,ACS

Operations Management

MELJUNELJUN

MELJUN CORTES,BSCS,ACS

Department of ICT

Faculty of Information

Technology


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MBA,MPA,BSCS,ACS

H

APTER

15

Scheduling

MELJUNELJUN


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MBA,MPA,BSCS,ACS

Scheduling: Establishing the timing of theuse of equipment, facilities and human

activities in an organization

Effective scheduling can yield

Cost savings

Increases in productivity

SchedulingScheduling


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MBA,MPA,BSCS,ACS

High-Volume SystemsHigh-Volume Systems

Flow system: High-volume system withStandardized equipment and activities

Flow-shop scheduling: Scheduling for high-

volume flow system

WorkCenter #1 Work Center#2

Output


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MBA,MPA,BSCS,ACS

Build A

A Done

Build B

B Done

Build C

C Done

Build D

Ship

JAN FEB MAR APR MAY JUN

On time!

Scheduling Manufacturing OperationsScheduling Manufacturing Operations

High-volume

Intermediate-

volume

Low-volume

Service

operations


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MBA,MPA,BSCS,ACS

High-Volume Success FactorsHigh-Volume Success Factors

Process and product design Preventive maintenance

Rapid repair when breakdown occurs Optimal product mixes

Minimization of quality problems

Reliability and timing of supplies


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MELJUN CORTES,MBA,MPA,BSCS,ACSMELJUN CORTES,MBA,MPA,BSCS,ACS

Intermediate-Volume SystemsIntermediate-Volume Systems

Outputs are between standardized high-volume systems and made-to-order job shops

Run size, timing, and sequence of jobs

Economic run size:

Q

DS

H

p

p u0

2

=


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Scheduling Low-Volume SystemsScheduling Low-Volume Systems

Loading- assignment of jobs to processcenters

Sequencing- determining the order inwhich jobs will be processed

Job-shop scheduling Scheduling for low-volume

systems with many

variationsin requirements


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Gantt Load ChartGantt Load Chart

Gantt chart- used as a visual aid for loading

and scheduling

W o r k

Cen te r

M on . T u es. W e d . T h u rs . F ri.

1 Job 3 Job 4

2 Jo b 3 Job 7

3 Job 1 Job 6 Job 7

4 Jo b 10

Figure 15.2


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Infinite loading Finite loading

Vertical loading

Horizontal loading

Forward scheduling

Backward scheduling

Schedule chart

LoadingLoading

CO S

SCS CS


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SequencingSequencing

Sequencing: Determine the order in whichjobs at a work center will be processed.

Workstation: An area where one personworks, usually with special equipment, on a

specialized job.

MELJUN CORTES

MBA MPA BSCS ACS


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SequencingSequencing

Priority rules: Simple heuristicsused to select the order inwhich jobs will be processed.

Job time: Time needed forsetup and processing of a job.

Everything is

#1 Priority

MELJUN CORTES MBA MPA BSCS ACSMELJUN CORTES

MBA MPA BSCS ACS


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Priority RulesPriority Rules

FCFS - first come, first served SPT - shortest processing time

EDD - earliest due date

CR - critical ratio

S/O - slack per operation

Rush - emergency

Top Priority

Table 15.2


MBA MPA BSCS ACS


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3.249.6722.17CR

2.686.3318.33EDD

2.636.6718.00SPT

2.939.0020.00FCFS

AverageNumber of

Jobs at the

Work Center

Average

Tardiness

(days)

Average

Flow Time

(days)Rule

Example 2Example 2Table 15.4


MBA MPA BSCS ACS


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Two Work Center SequencingTwo Work Center Sequencing

Johnsons Rule: technique for minimizingcompletion time for a group of jobs to be processed

on two machines or at two work centers.

Minimizes total idle time Several conditions must be satisfied


MBA MPA BSCS ACS


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Johnsons Rule ConditionsJohnsons 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


MBA MPA BSCS ACS


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Johnsons Rule Optimum SequenceJohnsons Rule Optimum Sequence

1. List the jobs and their times at each workcenter

2. Select the job with the shortest time

3. Eliminate the job from further consideration4. Repeat steps 2 and 3 until all jobs have been

scheduled


MBA MPA BSCS ACS


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Scheduling DifficultiesScheduling 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


MBA MPA BSCS ACS


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Minimizing Scheduling DifficultiesMinimizing Scheduling Difficulties

Set realistic due dates Focus on bottleneck operations

Consider lot splitting of large jobs


MBA MPA BSCS ACS


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Scheduling Service OperationsScheduling Service Operations

Appointment systems Controls customer arrivals for service

Reservation systems

Estimates demand for service Scheduling the workforce

Manages capacity for service

Scheduling multiple resources Coordinates use of more than one

resource


MBA MPA BSCS ACS


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Cyclical SchedulingCyclical Scheduling

Hospitals, police/fire departments, restaurants,supermarkets

Rotating schedules

Set a scheduling horizon Identify the work pattern

Develop a basic employee schedule

Assign employees to the schedule


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Service Operation ProblemsService Operation Problems

Cannot store or inventory services Customer service requests are random

Scheduling service involves

Customers Workforce

Equipment

MELJUN CORTES - Operations Management 15th Lecture (SCHEDULING)

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