Production Planning Control Operations Scheduling Dr.Na genG Prof.Zhibin JIANG Department of Industrial Engineering Management Shanghai Jiao Tong University
Production Planning & Control Dr. Na GENG Prof. Zhibin JIANG Department of Industrial Engineering & Management Shanghai Jiao Tong University Operations Scheduling
Operations Scheduling Contents ·Introduction Job Shop Scheduling Terminology ·Sequencing Rules Sequencing Theory for a Single Machine Sequencing Theory for Multiple Machines .Assembly Line Balancing Advanced Topics for Operations scheduling 国上泽充鱼大皇
Operations Scheduling Contents • Introduction • Job Shop Scheduling Terminology • Sequencing Rules • Sequencing Theory for a Single Machine • Sequencing Theory for Multiple Machines • Assembly Line Balancing • Advanced Topics for Operations scheduling
Introduction-What is Operations Scheduling Forecast of future demand Implement the production orders generated in MRP under given objectives Aggregate plan Allocate production resources (machine,workers et al.)to production orders (jobs or tasks Master production schedule(MPS) and their due dates)in an Schedule of production quantities by optimized manners; product and time period The results are time allocations of production resources to different Material Requirement Planning(MRP) jobs (job sequences on each Generate production orders and production resources); purchase order All the orders can be completed while all production resources are Operations Scheduling utilized with their loads being To meet quantities and time balanced. requirements for MRP @上浒充鱼大睾
Introduction-What is Operations Scheduling ? • Implement the production orders generated in MRP under given objectives ; • Allocate production resources (machine, workers et al.) to production orders (jobs or tasks and their due dates) in an optimized manners; • The results are time allocations of production resources to different jobs (job sequences on each production resources); • All the orders can be completed while all production resources are utilized with their loads being balanced. Forecast of future demand Aggregate plan Master production schedule (MPS) Schedule of production quantities by product and time period Material Requirement Planning (MRP ) Generate production orders and purchase order Operations Scheduling To meet quantities and time requirements for MRP
Introduction-Optimal schedule rules Significant issues for determining optimal or approximately optimal scheduling rules are the following. 1)The job arrival pattern 2)Number and variety of machine in the shop 3)Number of workers in the shop. 4)Particular flow patterns. 5)Evaluation of alternative rules. 国上泽道多
Introduction- Optimal schedule rules • Significant issues for determining optimal or approximately optimal scheduling rules are the following. 1) The job arrival pattern 2) Number and variety of machine in the shop. 3) Number of workers in the shop. 4) Particular flow patterns. 5) Evaluation of alternative rules
Introduction-Objectives of Job Shop Scheduling Objectives of operations scheduling 1)Meet due date; 2)Minimize WIP inventory; 3)Minimize the average flow time through the systems; 4)Provide for high machine/worker(time)utilization (minimize idle time); 5)Provide for accurate job status information; 6)Reduce setup cost; 7)Minimize production and worker costs Proper trade off between cost and quality is one of the most challenging strategic issues facing a firm today. 国上泽充鱼率
Introduction-Objectives of Job Shop Scheduling • Objectives of operations scheduling 1) Meet due date; 2) Minimize WIP inventory; 3) Minimize the average flow time through the systems; 4) Provide for high machine/worker (time) utilization (minimize idle time); 5) Provide for accurate job status information; 6) Reduce setup cost; 7) Minimize production and worker costs Proper trade off between cost and quality is one of the most challenging strategic issues facing a firm today
Introduction-Objectives of operations Scheduling Some of these objectives conflicts, Reduce WIP inventory Worker idle time may increase or machine utilization may decrease; Reasons:differences in the throughput rate from one part of the system to another may force the faster operations to wait. As an example,if there is no buffer for WIP between 1 and 2, what happens? Input Buffer (work-in-process) Output Fig8-3 A Process Composed of Two Operations in®ies¥克鱼大
Introduction-Objectives of operations Scheduling • Some of these objectives conflicts, Reduce WIP inventory Worker idle time may increase or machine utilization may decrease; Reasons: differences in the throughput rate from one part of the system to another may force the faster operations to wait. Fig 8-3 A Process Composed of Two Operations in Series As an example, if there is no buffer for WIP between 1 and 2, what happens?
Introduction-Objectives of operations Scheduling Some of these objectives conflicts, Finding the proper mix between WIP inventory and worker idle time is equivalent to choosing a point on the trade-off curve of these conflicting objectives. (a) 0000 59 Work-in-process 国上泽充道大多
Introduction-Objectives of operations Scheduling • Some of these objectives conflicts, Finding the proper mix between WIP inventory and worker idle time is equivalent to choosing a point on the trade-off curve of these conflicting objectives
Introduction-Objectives of operations Scheduling Some of these objectives conflicts, A true improvement in the overall system would mean that the entire trade-off curve undergoes a downward shift. 6 Improved system Work-in-process luol sodl to oaqmo W 圆上帝充道大酱
Introduction-Objectives of operations Scheduling • Some of these objectives conflicts, A true improvement in the overall system would mean that the entire trade-off curve undergoes a downward shift
Introduction-Functions of Scheduling and Control The following functions must be performed in scheduling and controlling a shop floor: Allocating orders,equipment,and personnel to work centers or other specified location-Short term capacity planning; Determining the sequence of orders(i.e.job priorities); Initializing performance of the scheduled work,commonly termed the dispatching of jobs; Shop-floor control,involving Reviewing the status and controlling the progress of orders as they are being worked on; Expediting the late and critical orders; Revising the schedules in light of changes in order
Introduction-Functions of Scheduling and Control • The following functions must be performed in scheduling and controlling a shop floor: Allocating orders, equipment, and personnel to work centers or other specified location-Short term capacity planning; Determining the sequence of orders (i. e. job priorities); Initializing performance of the scheduled work, commonly termed the dispatching of jobs; Shop-floor control, involving Reviewing the status and controlling the progress of orders as they are being worked on; Expediting the late and critical orders; Revising the schedules in light of changes in order status
Introduction-Elements of the Shop Floor Scheduling Problems The classic approaches to shop floor scheduling focuses on the following six elements: Job arrival patterns:static or dynamic Static:jobs arrive in single or batch; Dynamic:jobs arrive over time interval according to some statistical distribution. Numbers and variety of machines in the shop floor If there is only one machine or if a group of machines can be treated as one machine,the scheduling problem is much more simplified; As number of variety of machines increase,the more complex the scheduling problems is likely to become. 圈上泽充道大酱
Introduction-Elements of the Shop Floor Scheduling Problems • The classic approaches to shop floor scheduling focuses on the following six elements: Job arrival patterns: static or dynamic Static: jobs arrive in single or batch; Dynamic: jobs arrive over time interval according to some statistical distribution. Numbers and variety of machines in the shop floor If there is only one machine or if a group of machines can be treated as one machine, the scheduling problem is much more simplified; As number of variety of machines increase, the more complex the scheduling problems is likely to become
