Transcript Scheduling

Scheduling
Characteristics of a “job”
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Constituent operations
Due date
Time of arrival in shop
Starting time
Completion time
Flow time
Lateness
Characteristics of a
schedule
Two basic types of scheduling
Work-force
scheduling
Operations scheduling
Operations Scheduling
short-term plans designed to
implement the master
production schedule
 job
shop
 flow shop
Timing of job/operations
scheduled (Gantt chart)
 Job
or activity progress chart
 Machine chart
For n jobs, each requiring m
machines there are (n!)m possible
schedules
Measures
 Average
flow time of jobs
 Average lateness of jobs
 Makespan
Which of these would
Goldratt have said
 Idle time
was best?
 Past Due
 WIP
 Utilization
Scheduling heuristics
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FCFS – first come, first served
SPT – shortest processing time
EDD – earliest due date
Information Needed for
Scheduling
 Question:
What information
do you feel is needed to
accurately schedule an
operation?
Scheduling Class Activity
At the beginning:
400 birch in inventory
100 cherry past due
Equipment is set up for cherry
Scheduling Game Process.
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I will give you demand for week
Decide on how much of each type to process –
don’t forget open orders & birch forecast!
Record on decision log
Make a feasible schedule (don’t forget setups)
Turn in decision for week to me
When complete wait for actual birch demand for
week
Calculate profit/loss – give total to me
Get demand for new week