1、Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition1 Operations SchedulingOperations Scheduling Operations Management For Competitive Advantage CHASE AQUILANO JACOBS ninth edition Chapter 15 Operations ManagementFor Competitive Adva
2、ntage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition2 Chapter 15 Operations Scheduling Work Center Defined Typical Scheduling and Control Functions Job-shop Scheduling Examples of Scheduling Rules Shop-floor Control Principles of Work Center Scheduling Issues in Scheduling
3、Service Personnel Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition3 Work Center Defined A work center is an area in a business in which productive resources are organized and work is completed. May be a single machine, a group of
4、 machines, or an area where a particular type of work is done. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition4 Capacity and Scheduling Infinite loading (Example: MRP) Finite loading Forward scheduling Backward scheduling (Examp
5、le: MRP) Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition5 Typical Scheduling and Control Functions Allocating orders, equipment, and personnel. Determining the sequence of order performance. Initiating performance of the schedul
6、ed work. Shop-floor control. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition6 Work-Center Scheduling Objectives Meet due dates Minimize lead time Minimize setup time or cost Minimize work-in-process inventory Maximize machine ut
7、ilization Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition7 Priority Rules for Job Sequencing 1. First-come, first-served (FCFS) 2. Shortest operating time (SOT) 3. Earliest due date first 4. Earliest start date first (due date-l
8、ead time) 5. Least slack time remaining (STR) first Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition8 Priority Rules for Job Sequencing (Continued) 6. Least slack time remaining (per operation as opposed to per job) first 7. Smal
9、lest critical ratio (CR) first (due date-current date)/(number of days remaining) 8. Smallest queue ratio (QR) first (slack time remaining in schedule)/(planned remaining queue time) 9. Last come, first served (LCFS) 10. Random order or whim Operations ManagementFor Competitive Advantage The McGraw-
10、Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition9 Schedule Performance Measures Meeting due dates of customers or downstream operations. Minimizing the flow time (the time a job spends in the process). Minimizing work-in-process inventory. Minimizing idle time of machines or workers. Op
11、erations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition10 Example of Job Sequencing: First- Come First-Served Answer: FCFS Schedule Suppose you have the four jobs to the right arrive for processing on one machine. What is the FCFS schedul
12、e? Do all the jobs get done on time? No, Jobs B, C, and D are going to be late. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition11 Example of Job Sequencing: Shortest Operating Time Answer: Shortest Operating Time Schedule Suppos
13、e you have the four jobs to the right arrive for processing on one machine. What is the SOT schedule? Do all the jobs get done on time? No, Jobs A and B are going to be late. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition12 Exa
14、mple of Job Sequencing: Last-Come First-Served Answer: Last-Come First-Served Schedule No, Jobs B and A are going to be late. Suppose you have the four jobs to the right arrive for processing on one machine. What is the LCFS schedule? Do all the jobs get done on time? Operations ManagementFor Compet
15、itive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition13 Example of Job Sequencing: Earliest Due Date First Answer: Earliest Due Date First Suppose you have the four jobs to the right arrive for processing on one machine. What is the earliest due date first schedule
16、? Do all the jobs get done on time? No, Jobs C and B are going to be late. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition14 Example of Job Sequencing: Critical Ratio Method Suppose you have the four jobs to the right arrive for
17、 processing on one machine. What is the CR schedule? Do all the jobs get done on time? No, but since there is three- way tie, only the first job or two will be on time. In order to do this schedule the CRs have be calculated for each job. If we let today be Day 1 and allow a total of 15 days to do t
18、he work. The resulting CRs and order schedule are: CR(A)=(5-4)/15=0.06 (Do this job last) CR(B)=(10-7)/15=0.20 (Do this job first, tied with C and D) CR(C)=(6-3)/15=0.20 (Do this job first, tied with B and D) CR(D)=(4-1)/15=0.20 (Do this job first, tied with B and C) Operations ManagementFor Competi
19、tive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition15 Example of Job Sequencing: Johnsons Rule (Part 1) Suppose you have the following five jobs with time requirements in two stages of production. What is the job sequence using Johnsons Rule? Time in Hours Jobs St
20、age 1Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00 Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition16 Example of Job Sequencing: Johnsons Rule (Part 2) First, select the job with the smallest time in either stage. That
21、is Job D with the smallest time in the first stage. Place that job as early as possible in the unfilled job sequence below. Drop D out, select the next smallest time ( Job A), and place it 4th in the job sequence. Drop A out, select the next smallest time. There is a tie in two stages for two differ
22、ent jobs. In this case, place the job with the smallest time in the first stage as early as possible in the unfilled job sequence. Then place the job with the smallest time in the second stage as late as possible in the unfilled sequence. Job Sequence1 2 3 4 Job AssignedD A B C Time in Hours Jobs St
23、age 1Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00 Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition17 Shop-Floor Control: Major Functions 1. Assigning priority of each shop order. 2. Maintaining work-in-process quantity
24、 information. 3. Conveying shop-order status information to the office. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition18 Shop-Floor Control: Major Functions (Continued) 4. Providing actual output data for capacity control purpo
25、ses. 5. Providing quantity by location by shop order for WIP inventory and accounting purposes. 6. Providing measurement of efficiency, utilization, and productivity of manpower and machines. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ni
26、nth edition19 Input/Output Control InputOutput Planned input should never exceed planned output. Focuses attention on bottleneck work centers. Work Center Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition20 Principles of Work Cent
27、er 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. Operations Manage
28、mentFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition21 Principles of Job Shop Scheduling (Continued) 5. Speed of flow is most efficiently achieved by focusing on bottleneck work centers and jobs. 6. Reschedule every day. 7. Obtain feedback each day o
29、n jobs that are not completed at each work center. 8. Match work center input information to what the worker can actually do. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies, Inc., 2001CHASE AQUILANO JACOBS ninth edition22 Principles of Job Shop Scheduling (Continued) 9. Whe
30、n seeking improvement in output, look for incompatibility between engineering design and process execution. 10. Certainty of standards, routings, and so forth is not possible in a job shop, but always work towards achieving it. Operations ManagementFor Competitive Advantage The McGraw-Hill Companies
31、, Inc., 2001CHASE AQUILANO JACOBS ninth edition23 Personnel Scheduling in Services Scheduling consecutive days off Scheduling daily work times Scheduling hourly work times 第一、第二和第三组 第一组 首工序 尾工序 B 关键工序法(续) 关键工序法(续) 3.各组组内排序 第一组 M1 + M2 + M3 A 3 13 7 = 23 C 6 2 10 = 18 D 9 4 9 = 22 E 1 7 6 = 14 F 2 5
32、0 = 7 第一组内零件的投产顺序为 F E C D A 关键工序法(续) 第三组组内排序 只有一个零件 B 第二组组内排序 组内无零件 4.确定全部零件的投产顺序 第一组 第二组 第三组 F E C D A B 所以总的投产顺序为 : F E C D A B 零件甘特图 F E C D A B 优先规则法排序原理 M1 M2 M3 A11 B12 C43 等待队 E23 F43 等待队 C51 D31 E23 等待队 E32 A22 C51 优先规则排序法 优先规则举例: 规则名称 优先原则 优先级计算值 FCFS 先到的先安排 SPT 加工时间最短的作业 Pij TWORK 加工工作量最大
33、的工件 SLACK 余裕时间最少的工件 Di-t- SLACK/ FOPNR 余裕时间与剩余工序数 (Di-t- ) 之比最小的工件 m-i+1 工件号 第一工序 第二工序 第三工序 第四工序 总 工时 交货期 设备工时 设备 工时 设备工时 设备 工时 J1M1 5 M2 5 M37M432028 J2M2 7 M1 4 M31M461828 J3M3 2 M1 6 M43M271825 J4M3 4 M2 4 M16M421626 0 M2 M3 M4 M1 t11 t12 t13 t14 t21 t22 t23 t24 t31t41 t42 t43 t44 t32 t33 t34 7111623 23 22 27 2615 16 时间
