Operations Scheduling and Sequencing

Flashcards on Operations Scheduling and Sequencing.

Scheduling

Refers to the assignment of start and completion times to particular jobs, people, or equipment.

Sequencing

Refers to the determination of the order in which jobs or tasks are processed.

Shop performance

Focuses on machine utilization and work-in-process inventory. Common measures include makespan and flow time.

Due dates

Reflect promised delivery dates to customers and are vital to achieving customer satisfaction. Common measures include tardiness and lateness.

Staff scheduling

Attempts to match available personnel with the needs of the organization.

Appointments

Reservations of service time and capacity that help maximize the use of time-dependent service capacity, reduce the cost of providing services and the risk of no-shows, and accommodate customers and forecast their behavior.

Flow time

The amount of time a job spends in the shop or factory. Low flow times reduce WIP inventory.

Makespan

The time needed to process a given set of jobs. A short makespan aims to achieve high equipment utilization and resources by getting all jobs out of the shop quickly.

Lateness

The difference between the completion time and the due date (either positive or negative).

Tardiness

The amount of time by which the completion time exceeds the due date.

First come, first served (FCFS)

Used to prioritize jobs arriving intermittently. It focuses only on the time of arrival for the customer or job.

Shortest processing time (SPT)

Used to prioritize jobs in the short term. It minimizes average flow time and WIP inventory and maximizes resource utilization.

Earliest due date (EDD)

Also used to prioritize jobs in the short term. It minimizes the maximum of jobs past the due date.

Dispatching

The process of selecting jobs for processing and authorizing the work to be done.

Johnson’s Rule

Developed an algorithm for finding a minimum makespan schedule for a sequencing problem.

Schedule monitoring and control

Bar charts are helpful tools to monitor planned schedules, display and track jobs that are behind, on, or ahead of schedule.

The Clarke-Wright Method

A heuristic procedure that assumes each customer is being serviced individually from the depot and seeks to combine customers into longer routes to reduce the total travel time and remain within capacity restrictions.