Chapter 17 - Scheduling. This chapter includes contents: Objectives in scheduling, loading, sequencing, monitoring, advanced planning and scheduling systems, theory of constraints, employee scheduling.
OPERATIONS MANAGEMENT: Creating Value Along the Supply Chain, Canadian Edition Robert S Russell, Bernard W Taylor III, Ignacio Castillo, Navneet Vidyarthi § CHAPTER 17 Scheduling § Learning Objectives Objectives in Scheduling Loading Sequencing Monitoring Advanced Planning and Scheduling Systems Theory of Constraints Employee Scheduling 17-2 § What is Scheduling? Last stage of planning before production occurs Specifies when labor, equipment, and facilities are needed to produce a product or provide a service 17-3 § Scheduled Operations Process Industry Linear programming EOQ with noninstantaneous replenishment Mass Production Assembly line balancing Project Project -scheduling techniques (PERT, CPM) Batch Production Aggregate planning Master scheduling Material requirements planning (MRP) Capacity requirements planning (CRP) 17-4 § Objectives in Scheduling Meet customer due dates Minimize job lateness Minimize response time Minimize completion time Minimize time in the system Minimize overtime Maximize machine or labor utilization Minimize idle time Minimize work-inprocess inventory 17-5 § Shop Floor Control (SFC) Schedule and monitor day-to-day job shop production Also called production control and production activity control (PAC) Performed by production control department Loading - check availability of material, machines, and labor Sequencing - release work orders to shop and issue dispatch lists for individual machines Monitoring - maintain progress reports on each job until it is complete 17-6 § Loading Process of assigning work to limited resources Perform work with most efficient resources Use assignment method of linear programming to determine allocation 17-7 § Assignment Method Perform row reductions subtract minimum value in each row from all other row values Perform column reductions subtract minimum value in each column from all other column values Cross out all zeros in matrix use minimum number of horizontal and vertical lines If number of lines equals number of rows in matrix, then optimum solution has been found Make assignments where zeros appear ‾ ‾ ‾ ‾ Else modify matrix: subtract minimum uncrossed value from all uncrossed values add it to all cells where two lines intersect other values in matrix remain unchanged Repeat steps and until optimum solution is reached 17-8 § Assignment Method 17-9 § Assignment Method 17-10 § Advanced Planning and Scheduling Systems Advanced planning and scheduling (APS) Add-ins to ERP systems Constraint-based programming (CBP) identifies a solution space and evaluates alternatives Genetic algorithms based on natural selection properties of genetics Manufacturing execution system (MES) monitors status, usage, availability, quality 17-34 § Advanced Planning and Scheduling 17-35 § Theory of Constraints Not all resources are used evenly Finite scheduling approach Concentrate on the ”bottleneck” resource Synchronize flow through the bottleneck Use process and transfer batch sizes to move product through facility 17-36 § Drum-Buffer-Rope Drum Bottleneck, beating to set the pace of production for the rest of the system Buffer Inventory placed in front of the bottleneck to ensure it is always kept busy Determines output or throughput of the system Rope Communication signal; tells processes upstream when they should begin production 17-37 § TOC Scheduling Procedure Identify bottleneck Schedule job first whose lead time to bottleneck is less than or equal to bottleneck processing time Forward schedule bottleneck machine Backward schedule other machines to sustain bottleneck schedule Transfer in batch sizes smaller than process batch size 17-38 § Synchronous Manufacturing 17-39 § Synchronous Manufacturing 17-40 § Synchronous Manufacturing 17-41 § Employee Scheduling Labor is very flexible resource Scheduling workforce is complicated, repetitive task Assignment method can be used Heuristics are commonly used 17-42 § Employee Scheduling Heuristic Let N = no of workers available Di = demand for workers on day i X = day working O = day off Assign the first N - D1 workers day off Assign the next N - D2 workers day off Continue in a similar manner until all days are have been scheduled If number of workdays for full time employee < 5, assign remaining workdays so consecutive days off are possible 17-43 § Employee Scheduling 17-44 § Employee Scheduling 17-45 § Employee Scheduling 17-46 § Automated Scheduling Systems Staff Scheduling Assign workers to standardize shift patterns Schedule Bidding Workers bid for certain shift positions or schedules Schedule Optimization Creates demand-driven forecast of labor needs Assigns workers to variable schedules Uses mathematical programming and artificial intelligence techniques 17-47 § COPYRIGHT Copyright © 2014 John Wiley & Sons Canada, Ltd All rights reserved Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd The purchaser may make back-up copies for his or her own use only and not for distribution or resale The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein ... time 1 7-1 5 § Simple Sequencing Rules 1 7-1 6 § Simple Sequencing Rules: FCFS 1 7-1 7 § Simple Sequencing Rules: DDATE 1 7-1 8 § Simple Sequencing Rules: SLACK 1 7-1 9 § Simple Sequencing Rules: SPT 1 7-2 0... Rules: Summary 1 7-2 1 § Sequencing Jobs Through Two Serial Process 1 7-2 2 § Sequencing With Excel 1 7-2 3 § Johnson’s Rule 1 7-2 4 § Johnson’s Rule 1 7-2 5 § Excel for Johnson’s Rule 1 7-2 6 § Guidelines... lines intersect other values in matrix remain unchanged Repeat steps and until optimum solution is reached 1 7-8 § Assignment Method 1 7-9 § Assignment Method 1 7-1 0 § Assignment Method - Setup Solution