Chap 15 - Short-Term Scheduling Delta Airlines - 10 of flights are disrupted, 1

1. Chap 15 - Short-Term Scheduling Delta Airlines - 10% of flights are disrupted, 1/2 because of weather. Need to make last minute adjustments, lost revenue, overtime pay, food and lodging vouchers. $33 million - operations control center in Atlanta Schedule and route changes. Put people onto rival airlines. *F15.1 p617 Scheduling deals with the timing of operations, it begins with capacity planing, facility and equipment acquisitions. It produces job sequences and specific assignments of personnel, material and machinery. Scheduling goods and services in the short run (weekly, daily, or hourly basis). *Versatility in scheduling results in parts ready on a just-in-time basis, with low setup times, little work-in-process, and high machine utilization. By scheduling effectively, create greater capacity, lowers cost. This results in added capacity, flexibility provides faster delivery. Good scheduling contributes to dependable delivery.

2. Scheduling Examples: Hospital - Outpatient treatments, Operating rooms. University - Instructors, Classrooms. Factory - Production, Purchases. *Forward scheduling: starts as soon as the job requirements are known. Used by hospitals, clinics, fine restaurants. Jobs performed to customer order. Delivery as soon as possible. Can cause buildup of WIP. *Backward scheduling: begins with the due date of the final operation; schedules jobs in reverse order. Used in many manufacturing environments, catering, scheduling surgery. Assignments of date does not ensure that the work will be performed on time. machine breakdowns, absenteeism, quality problems, shortages. The Goals of Short-Term Scheduling, used to evaluate scheduling performance: Minimize completion time. Maximize utilization (personnel and equipment). Minimize WIP inventory. Minimize customer wait time.

3. Good scheduling should be simple, clear, easily understood, easy to carry out, flexible, realistic. The objective of scheduling is to optimize the use of resources so that production objectives are met. Inconsistent schedules often force employees to snooze, p619 20 million Americans work round-the-clock, graveyard shifts giving all workers several days off between shift changes fewer and less random schedule changes. A) Process-Focused Work Centers. High variety, low volume systems, job shops. Products made to order. Products need different materials and processing. *Scheduling can be complex. Loading - Assigning jobs to work centers. 2 Approaches: 1) Gantt charts - visual aids used to schedule resources and allocate time . Developed in late 1800s. a) Gantt Load Chart p622 - y axis is work center. b) Gantt Scheduling Chart p623 - y axis is job. Many versions, scheduled verse actual.

4. 2) Assignment method of linear programming - like module B. Minimize total costs or time required to perform tasks E4 p624, numbers in the table can be costs or times associated with each particular assignment. American league umpires, conflicting objectives: 1) Balance crew assignments among all teams. 2) Minimize travel costs. **Sequencing - determining the order that jobs will be done. Priority rules - especially applicable for process focused facilities like clinics, print shops, manufacturing job shops. Try to minimize completion time, # of jobs in the system, lateness, while maximizing facility utilization. a) First come, first served - The first job to arrive at a work center is processed first. Average performance on most scheduling criteria. Appears ‘fair’ to customers - Important for service, restaurants. b) Earliest due date - The job with the earliest due date is processed first. Emergency rooms & bad managers fighting fires.

5. c) Shortest processing time - The job with the shortest processing time is processed first. Best for minimizing job flow and # of jobs in the system d) Longest processing time - The job with the longest processing time is processed first. *Bottleneck Work Centers - Have less capacity than prior or following work centers, limits production output. Remedies: Increase capacity of bottleneck. Develop other routings or subcontract. Schedule throughput to match bottleneck, accept idleness at other workstations. Ensuring well-trained employees operate and maintain this constraint. Moving inspections and tests to a position just before the constraint. An hour lost at a bottleneck is an hour lost of the whole system. An hour saved at a non-bottleneck is a mirage. B) Repetitive Manufacturing - make standard products from modules. Want to satisfy customer demands, lower inventory investment, reduce the batch (or lot)size, and utilize equipment. Level Material Use - the use of frequent, high quality, small lot sizes to contribute to just-in-time production.

6. Advantages: Lower inventory levels. Shorter lead times. Improved component quality and hence improved product quality. Reduced floor space requirements. Improved communication among employees because they are closer together. Smoother production process, no “hidden” problems. McDonalds - the manager was spending 8 hours to prepare manually the work schedule for 150 employees. Forecasting sales - translated to hourly staffing needs for grill, counter, & drive through. Match to part-time availability's and work skills. Takes 15 minutes on PC and you can do “what if” analysis with a variety of operating conditions. C) Services - try to match fluctuation customer demand with the capability to meet the demand. *Other two emphasis was on material, but for services emphasis is on staffing levels. Services seldom have inventories. *Services are labor intensive and demand for labor can be highly variable. Bring in extra workers, often part-timers.

7. Systems: Appointment, doctors & lawyers. First-come-first-serve, retail shops, post office, fast food. Reservations, car agencies, symphonies, hotels, restaurants, minimizing customer waiting time. *Banks - cross training, loan officers can help the tellers during demand surge. *Airlines - flight crews, FAA work limitations verse union guarantee crew pay. Also need to make efficient use of the aircraft (large investment). SWA - 15 minute turnaround for many years. US Air - 7 trips/day up from 6. Cutting turnaround time from 45 min to 20. Need to clean, replenish food and drinks, fuel, baggage and freight.. *Cyclical Scheduling. Allow each employee to pick a “slot” in order of seniority. Changes to the schedule - need to trade with someone. No computer needed. Employees are usually like it. Offer predictability and flexibility. Mrs Fields Cookies p639 - every store could access headquarters scheduling expertise (centralized).