1. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-1 Operations Management Short-Term Scheduling Chapter 15

2. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-2  Shows relative workload in facility  Disadvantages  Does not account for unexpected events  Must be updated regularly Gantt Load Chart

3. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-3 SMTWTFS Day Job Job A Job B Job C Repair n Used to monitor job progress Today Gantt Scheduling Chart

4. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-4  Specifies order jobs will be worked  Sequencing rules  First come, first served ( FCFS )  Shortest processing time ( SPT )  Earliest due date ( EDD )  Longest processing time ( LPT )  Critical ratio ( CR )  Johnson’s rule Sequencing

5. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-5 Priority Rules for Dispatching Jobs First come, first served The first job to arrive at a work center is processed first Earliest due date The job with the earliest due date is processed first Shortest processing time The job with the shortest processing time is processed first Longest processing time The job with the longest processing time is processed first Critical ratio The ratio of time remaining to required work time remaining is calculated, and jobs are scheduled in order of increasing ratio. FCFS EDD SPT LPT CR

6. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-6  Process first job to arrive at a work center first  Average performance on most scheduling criteria  Appears ‘fair’ & reasonable to customers  Important for service organizations  Example: Restaurants First Come, First Served Rule

7. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-7  Process job with earliest due date first  Widely used by many companies  If due dates important  If MRP used  Due dates updated by each MRP run  Performs poorly on many scheduling criteria Earliest Due Date Rule

8. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-8  Ratio of time remaining to work time remaining  Process job with smallest CR first  Performs well on average lateness CR Time remaining Work daysremaining Due date- Today's date Work (lead) time remaining = = Critical Ratio (CR)

9. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-9 Advantages of the Critical Ratio Scheduling Rule Use of the critical ratio can help to:  determine the status of a specific job  establish a relative priority among jobs on a common basis  relate both stock and make-to-order jobs on a common basis  adjust priorities and revise schedules automatically for changes in both demand and job progress  dynamically track job progress and location

10. PowerPoint presentation to accompany Operations Management, 6E (Heizer & Render) © 2001 by Prentice Hall, Inc., Upper Saddle River, N.J. 07458 15-10  Used to sequence N jobs through 2 machines in the same order © 1995 Corel Corp. SawDrill Job A Job B Job C Jobs (N = 3) Johnson’s Rule