h 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; vRevising the schedules in light of changes in order status. ®上济充道大
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 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. 圈上泽充鱼大姿
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 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
h Introduction-Elements of the Shop Floor Scheduling Problems (Continued) Ratio of workers to machines Machine limited system:more workers than machine or equal number workers and machines; Labor-limited system:more machines than worker. Flow pattern of jobs:flow shop or job shop Flow shop:all jobs follow the same paths from one machine to the next; Job shop:no similar pattern of movement of jobs from one machine to the next. 圈上浒充鱼大
Introduction-Elements of the Shop Floor Scheduling Problems • (Continued) Ratio of workers to machines Machine limited system: more workers than machine or equal number workers and machines; Labor-limited system: more machines than worker. Flow pattern of jobs: flow shop or job shop Flow shop: all jobs follow the same paths from one machine to the next; Job shop: no similar pattern of movement of jobs from one machine to the next
Introduction-Elements of the Shop Floor Scheduling Problems (Continued) √Job sequencing Sequencing or priority sequencing:the process of determining which job is started first on some machines or work center by priority rule; Priority rule:the rule used for obtaining a job sequencing; Priority rule evaluation criteria To meet corresponding objectives of scheduling; Common standard measures: > Meeting due date of customers or downstream operations; Minimizing flow time(the time a job spends in the shop flow); > Minimizing WIP; > Minimizing idle time of machines and workers (Maximizing utilization). 圈上泽充鱼大姿
Introduction-Elements of the Shop Floor Scheduling Problems • (Continued) Job sequencing Sequencing or priority sequencing: the process of determining which job is started first on some machines or work center by priority rule; Priority rule: the rule used for obtaining a job sequencing; Priority rule evaluation criteria To meet corresponding objectives of scheduling; Common standard measures: Meeting due date of customers or downstream operations; Minimizing flow time (the time a job spends in the shop flow); Minimizing WIP; Minimizing idle time of machines and workers (Maximizing utilization)
Introduction-Elements of the Job Shop Scheduling Problems Flow shop: Each of the n jobs must be processed through the m machines in the same order. Task Each job is processed exactly once on each machine. An assembly line is a classic example of flow shop Every cars go through all the stations one by one in the same sequences; Same tasks are performed on each car in each station; Its operations scheduling is simplified as assembly line balancing; An assembly balancing problem is to determine the number of stations and to allocate tasks to each station. @上浒充道大皇
Introduction-Elements of the Job Shop Scheduling Problems An assembly line is a classic example of flow shop • Every cars go through all the stations one by one in the same sequences; • Same tasks are performed on each car in each station; • Its operations scheduling is simplified as assembly line balancing; • An assembly balancing problem is to determine the number of stations and to allocate tasks to each station. Flow shop: • Each of the n jobs must be processed through the m machines in the same order. • Each job is processed exactly once on each machine