运营管理第14版蔡斯ipptchap022

WORK CENTER SCHEDULING Chapter Twenty-Two Copyright 2014 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill/Irwin Learning Objectives LO22-1: Explain work center scheduling. LO22-2: Analyze scheduling problems using priority rules and more specialized techniques. LO22-3: Apply scheduling techniques to the manufacturing shop floor. LO22-4: Analyze employee schedules in the service sector. 22-2 Manufacturing Execution Systems Manufacturing execution system (MES): an information system that schedules, dispatches, tracks, monitors, and controls production Real-time linkage to: MRP Product and process planning Systems that extend beyond the factory Service execution system (SES): an information system that links schedules, dispatches, tracks, monitors, and controls the customers encounters with the service organization 22-3 The Nature and Importance of Work Centers Work center: an area in which production resources are organized and work is completed May be a single machine, a group of machines, or an area where work is done Can be organized according to function, product in a flow, or group technology Jobs need to be routed between functionally organized work centers to complete the work 22-4 Loading Infinite loading: work is assigned to a work center based on what is needed No consideration to capacity Finite loading: schedules each resource using the setup and run time required for each order Determines exactly what will be done by each resource at every moment during the day 22-5 Scheduling Forward scheduling: the system takes an order and schedules each operation that must be completed forward in time Can tell the earliest date an order can be completed Backward scheduling: starts with due date and schedules the required operations in reverse sequence Can tell when an order must be started in order to be done by a specific date 22-6 Limitations Machine-limited process: equipment is the critical resource that is scheduled Labor-limited process: people are the key resource that is scheduled Most actual processes are either labor limited or machine limited but not both 22-7 Types of Manufacturing Processes and Scheduling Approaches 22-8 Typical Scheduling and Control Functions 1.Allocating orders, equipment, and personnel 2.Determining the sequence of order performance 3.Initiating performance of the scheduled work 4.Shop-floor control 22-9 Objectives of Work-Center Scheduling 1.Meet due dates 2.Minimize lead time 3.Minimize setup time or cost 4.Minimize work-in-process inventory 5.Maximize machine utilization 22-10 Job Sequencing Sequencing: the process of determining the job order on machines or work centers Also known as priority sequencing Priority rules: the rules used in obtaining a job sequence Can be simple or complex Can use one or more pieces of information Common rules shown on next slide 22-11 Priority Rules for Job Sequencing 22-12 Standard Measures of Schedule Performance 1.Meeting due dates 2.Minimizing the flow time 3.Minimizing work-in-process inventory 4.Minimizing idle time 22-13 Example 22.1: n Jobs on One Machine 22-14 Example 22.1: FCFS and SOT Rules 22-15 Example 22.1: EDD and LCFS Rules 22-16 Example 22.1: Random and STR Rules 22-17 Comparison of Priority Rules 22-18 Scheduling n Jobs on Two Machines Two or more jobs must be processed on two machines in a common sequence. Wish to minimize the flow time from the beginning of the first job to the finish of the last job. Use Johnsons rule. 22-19 Steps to Johnsons Rule 1.List the operation time for each job. 2.Select the shortest operation time. 3.If the shortest time is on the first machine, do first. If the shortest time is on the second machine, do the job last. For ties, do first. 4.Repeat steps 2-3 for each remaining job. 22-20 Example 22.2: n Jobs on Two Machines 22-21 Example 22.2: Scheduling Jobs 22-22 Example 22.2: Optimal Schedule of Jobs Using Johnsons Rule 22-23 Scheduling a Set Number of Jobs on the Same Number of Machines Some work centers have enough machines to start all the jobs. Here the issue is the particular assignment of individual jobs to individual machines. Assignment method: a special case of the transportation method of linear programming. 1.There are n things to be distributed to n destinations. 2.Each thing assigned to one and only one destination. 3.Only one criterion can be used. 22-24 Example 22.3: Assignment Method Assignment Matrix Showing Machine Processing Costs for Each Job 22-25 Example 22.3: Step 1 Row Reduction 22-26 Example 22.3: Step 2 Column Reduction 22-27 Example 22.3: Step 3 Apply Line Test 22-28 Example 22.3: Step 4 Additional Reduction 22-29 Example 22.3: Optimal Solution 22-30 Example 22.3: Optimal Assignment and Their Costs Job I to Machine E$3 Job II to Machine B4 Job III to Machine C2 Job IV to Machine D5 Job V to Machine A3 Total Cost$17 22-31 Shop-Floor Control: Major Functions 1.Assigning priority of each shop order 2.Maintaining WIP quantity information 3.Conveying shop-order status information to the office 4.Providing actual output data for capacity control purposes 5.Providing quantity by location by shop order for WIP inventory and accounting 6.Providing measurement of efficiency, utilization, and productivity 22-32 Gantt Chart 22-33 Tools of Shop-Floor Control 1.The daily dispatch list 2.Various status and exception reports a.Anticipated delay report b.Scrap report c.Rework report d.Performance summary reports e.Shortage list 3.An input/output control report 22-34 Some Basic Tools of Shop-Floor Control 22-35 Shop Capacity Control Load Flow 22-36 Principles of Work Center Scheduling 1.There is a direct equivalence between work flow and cash flow. 2.The effectiveness of any job shop should be measured by speed of flow through the shop. 3.Schedule jobs as a string, with process steps back-to-back. 4.A job once started should not be interrupted. 5.Speed of flow is most efficiently achieved by focusing on bottleneck work centers and jobs. 22-37 Principles of Job Shop Scheduling (continued) 6.Reschedule every day. 7.Obtain feedback each day on jobs that are not completed at each work center. 8.Match work center input information to what the worker can actually do. 9.When improving output, look for incompatibility between engineering design and process execution. 10.Certainty of standards, routings, and so forth is not possible, but always work toward achieving it. 22-38 Personnel Scheduling in Services Scheduling consecutive days off Scheduling daily work times Scheduling hourly work times 22-39 Software for Employee Scheduling 22-40 ScheduleSource Inc. of Broomfield, Colorado, offers an integrated suite of tools for workforce management named TeamWork. At the heart of TeamWork is a customizable and automated employee scheduling system. The benefits of TeamWork software include features such as Web based Optimized schedules Zero conflict scheduling Time and attendance recordkeeping E-ma