Operations Management Chapter 15 – Short-Term Scheduling PowerPoint presentation to accompany Heizer/Render Principles of Operations Management, 7e Operations Management, 9e © 2008 Prentice Hall, Inc 15 – Outline  Global Company Profile: Delta Air Lines  The Strategic Importance of ShortTerm Scheduling  Scheduling Issues  Forward and Backward Scheduling  Scheduling Criteria © 2008 Prentice Hall, Inc 15 – Outline – Continued  Scheduling Process-Focused Facilities  Loading Jobs  Input-Output Control  Gantt Charts  Assignment Method © 2008 Prentice Hall, Inc 15 – Outline – Continued  Sequencing Jobs  Priority Rules for Dispatching Jobs  Critical Ratio  Sequencing N Jobs on Two Machines: Johnson’s Rule  Limitations of Rule-Based Dispatching Systems  Finite Capacity Scheduling (FCS) © 2008 Prentice Hall, Inc 15 – Outline – Continued  Theory of Constraints  Bottlenecks  Drum, Buffer, Rope  Scheduling Repetitive Facilities  Scheduling Services  Scheduling Service Employees with Cyclical Scheduling © 2008 Prentice Hall, Inc 15 – Learning Objectives When you complete this chapter you should be able to: Explain the relationship between shortterm scheduling, capacity planning, aggregate planning, and a master schedule Draw Gantt loading and scheduling charts Apply the assignment method for loading jobs © 2008 Prentice Hall, Inc 15 – Learning Objectives When you complete this chapter you should be able to: Name and describe each of the priority sequencing rules Use Johnson’s rule Define finite capacity scheduling List the steps in the theory of constraints Use the cyclical scheduling technique © 2008 Prentice Hall, Inc 15 – Delta Airlines  About 10% of Delta’s flights are disrupted per year, half because of weather  Cost is $440 million in lost revenue, overtime pay, food and lodging vouchers  The $33 million Operations Control Center adjusts to changes and keeps flights flowing  Saves Delta $35 million per year © 2008 Prentice Hall, Inc 15 – Strategic Importance of Short-Term Scheduling  Effective and efficient scheduling can be a competitive advantage  Faster movement of goods through a facility means better use of assets and lower costs  Additional capacity resulting from faster throughput improves customer service through faster delivery  Good schedules result in more dependable deliveries © 2008 Prentice Hall, Inc 15 – Scheduling Issues  Scheduling deals with the timing of operations  The task is the allocation and prioritization of demand  Significant issues are  The type of scheduling, forward or backward  The criteria for priorities © 2008 Prentice Hall, Inc 15 – 10 Scheduling Repetitive Facilities  Advantages include: Lower inventory levels Faster product throughput Improved component quality Reduced floor-space requirements Improved communications Smoother production process © 2008 Prentice Hall, Inc 15 – 65 Scheduling Services Service systems differ from manufacturing Manufacturing Schedules machines and materials Inventories used to smooth demand Machine-intensive and demand may be smooth Scheduling may be bound by union contracts Few social or behavioral issues © 2008 Prentice Hall, Inc Services Schedule staff Seldom maintain inventories Labor-intensive and demand may be variable Legal issues may constrain flexible scheduling Social and behavioral issues may be quite important 15 – 66 Scheduling Services  Hospitals have complex scheduling system to handle complex processes and material requirements  Banks use a cross-trained and flexible workforce and part-time workers  Retail stores use scheduling optimization systems that track sales, transactions, and customer traffic to create work schedules in less time and with improved customer satisfaction © 2008 Prentice Hall, Inc 15 – 67 Scheduling Services  Airlines must meet complex FAA and union regulations and often use linear programming to develop optimal schedules  24/7 operations like police/fire departments, emergency hot lines, and mail order businesses use flexible workers and variable schedules, often created using computerized systems © 2008 Prentice Hall, Inc 15 – 68 Demand Management  Appointment or reservation systems  FCFS sequencing rules  Discounts or other promotional schemes  When demand management is not feasible, managing capacity through staffing flexibility may be used © 2008 Prentice Hall, Inc 15 – 69 Scheduling Service Employees With Cyclical Scheduling  Objective is to meet staffing requirements with the minimum number of workers  Schedules need to be smooth and keep personnel happy  Many techniques exist from simple algorithms to complex linear programming solutions © 2008 Prentice Hall, Inc 15 – 70 Cyclical Scheduling Example Determine the staffing requirements Identify two consecutive days with the lowest total requirements and assign these as days off Make a new set of requirements subtracting the days worked by the first employee Apply step to the new row Repeat steps and until all requirements have been met © 2008 Prentice Hall, Inc 15 – 71 Cyclical Scheduling Example Employee M T W T F S S 5 3 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 72 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 73 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 74 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Employee 2 2 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 75 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Employee 2 2 Employee 1 2 2 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 76 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Employee 2 2 Employee 1 2 2 Employee 1 1 1 Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 77 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Employee 2 2 Employee 1 2 2 Employee 1 1 1 Employee Capacity (Employees) Excess Capacity © 2008 Prentice Hall, Inc 15 – 78 Cyclical Scheduling Example M T W T F S S Employee 5 3 Employee 4 3 Employee 3 3 Employee 2 2 Employee 1 2 2 Employee 1 1 1 Employee Capacity (Employees) 5 3 Excess Capacity 0 0 © 2008 Prentice Hall, Inc 15 – 79 ... crews, catering, gate, ticketing personnel Table 15. 1 © 2008 Prentice Hall, Inc 15 – 11 Scheduling Flow Figure 15. 1 © 2008 Prentice Hall, Inc 15 – 12 Forward and Backward Scheduling  Forward... Output 270 270 270 270 Cumulative Deviation –50 –100 150 –200 –20 –10 +5 Cumulative Change in Backlog Figure 15. 2 © 2008 Prentice Hall, Inc 15 – 22 Input-Output Control Example Work Center DNC... Apply the assignment method for loading jobs © 2008 Prentice Hall, Inc 15 – Learning Objectives When you complete this chapter you should be able to: Name and describe each of the priority sequencing