What does scheduling include?
Sequencing
Personnel scheduling
operating room planning
project scheduling
Define scheduling
timing of usage of resources
often represented in Gantt charts
What is the scheduling hierarchy?
- Aggregate planning
- master production schedule
- material requirements planning
- shop floor schedule
Two types of sequencing
Flow shop
- all jobs processed on all machines in same order
- each job once on each machine
- example: assembly line
Job shop
- not all jobs require all machines
- sometimes same machine multiple times
- different jobs need machines in different order
Which performance measures exist?
Completion time
Tardiness
Flow time
Makespan
Define completion time
-exact time when final job finishes on final machine
Define tardiness
-Difference between due date and completion date
Define flow time
-Duration between release of a job and time of completion
Define makespan
- duration needed to complete all jobs
- from release of ´first job to completion of final job
which major goals does scheduling have?
Minimize flow times
- minimize max. flow time
- minimize average flow size for all jobs
Maximize punctuality
- only if every job had due date
- minimize total tardiness
- minimize nr. of tardy jobs
Which priority rules exist
First come first served (FCFS)
Shortest processing time (SPT)
Earliest due date (EDD)
What is project scheduling
- Precedence relations
- displayed as network
what is the critical path?
- path with no slack
- helps identify processes that are critical in regards to timing
define slack
time between differnt steps in project process
-should be minimized as it causes additional costs
