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MBA 8452 Systems and Operations Management

MBA 8452 Systems and Operations Management. Operations Scheduling. Objectives. Explain work center capacity Describe infinite and finite loading, forward and backward scheduling Solve scheduling problems Explain scheduling in service operations. Scheduling.

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MBA 8452 Systems and Operations Management

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  1. MBA 8452 Systems and Operations Management Operations Scheduling

  2. Objectives • Explain work center capacity • Describe infinite and finite loading, forward and backward scheduling • Solve scheduling problems • Explain scheduling in service operations

  3. Scheduling • Allocates resources over time (short-run) to accomplish specific tasks • Examples • Hospital: operating room, staff • University: course, classroom, instructor • Airline: flight departure, arrival, and crew • Factory: product production, worker

  4. Operations Scheduling • Work Center • An area in a business in which productive resources are organized and work is completed • Capacity and Scheduling • Infinite loading • Finite loading • Forward scheduling • Backward scheduling

  5. Typical Scheduling and Control Functions • Allocating orders, equipment, and personnel to work centers • Determining the sequence of job orders • Initiating performance of the scheduled work • Shop-floor control

  6. Work-Center Scheduling Objectives • Meet due dates • Minimize lead time • Minimize setup time or cost • Minimize work-in-process inventory

  7. Some Priority Rules for Job Sequencing • First-come, first-served (FCFS) • Shortest operating/processing time (SOT) • Earliest due date (DDate) • Least slack time remaining (STR) (due date - current date) - (remaining processing time) • Smallest critical ratio (due date-current date)/(remaining processing time)

  8. Job SequencingPerformance Measures • Average Lateness - meet due dates of customers or downstream operations • Mean Flow Time - minimize the time a job spends in the process

  9. Job Sequencing on One MachineExample Six jobs are lined up for processing on one machine. Their processing times (in order of arrival) and due dates are listed below What is the sequencing schedule using FCFS, SOT, STR, or DDate rule?

  10. Job Sequencing on One MachineExample--FCFS Rule Average lateness = 9.3 days Mean flow time = 22.5 days

  11. Job Sequencing on One MachineExample--SOT Rule Average lateness = 5.67 days Mean flow time = 18 days

  12. Job Sequencing on One MachineExample--STR Rule Average lateness = 7.67 days Mean flow time = 22.33 days

  13. Job Sequencing on One MachineExample--DDate Rule Average lateness = 5.17 days Mean flow time = 19.17 days

  14. Job Sequencing on One MachineExample--Schedule Chart Time (in days)

  15. Job Sequencing on One MachineSome General Results • For job sequencing on one machine/work center, schedule completion time (makespan) is always the same regardless of the job order • SOT minimizes average flow time and average waiting time • Earliest DDate rule minimizes the worst (maximum) lateness

  16. Job Sequencing on Two MachinesJohnson’s Rule • Minimizes the time to complete all jobs in both work centers/machines (makespan) • Procedure of Applying Johnson’s Rule • List the operation times for all jobs • Select the shortest operating time overall • If the SOT is for the: 1st machine - schedule that job first 2nd machine - schedule that job last • Repeat steps  and , until all jobs are scheduled

  17. Job Sequencing on Two MachinesExample--Johnson’s Rule Five jobs need to be processed at two workstations with the following processing time requirement What is the best sequence of jobs that minimizes the flow time of all jobs? Answer: B-A-D-E-C

  18. Job Sequencing on Two MachinesExample--Schedule Chart Makespan = 65 hours

  19. Shop-Floor (Production Activity) ControlMajor Functions 1. Assign priority to each shop order 2. Maintain work-in-process quantity information 3. Convey shop-order status information 4. Provide actual output data for capacity control purposes 5. Provide quantity by location by shop order for WIP inventory and accounting purposes 6. Provide measurement of efficiency, utilization, and productivity of manpower and machines

  20. Input Output Input/Output Control • Planned input should never exceed planned output (in the long run) • Focuses attention on bottleneck work centers Work Center

  21. Personnel Scheduling in Services • Scheduling consecutive days off • Scheduling daily work times • Scheduling hourly work times

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