lecture8bw - SMA 6304 M2 Factory Planning and Scheduling...

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SMA 6304 M2 Factory Planning and Scheduling Multi-Stage Control and Scheduling Stanley B. Gershwin November 15 and 20, 2001 Copyright c 2000 Stanley B. Gershwin. All rights reserved. Definitions Events may be controllable or not, and predictable or not. controllable uncontrollable predictable loading a part lunch unpredictable ??? machine failure Copyright c 2001 Stanley B. Gershwin. All rights reserved. 2 Definitions Scheduling is the selection of times for future controllable events. Ideally, scheduling systems should deal with all controllable events, and not just production. That is, they should select times for operations, set-up changes, preventive maintenance, etc. Copyright c 2001 Stanley B. Gershwin. All rights reserved. 3
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Definitions Because of recurring random events, scheduling is an on-going process, and not a one-time calculation. Scheduling, or shop floor control, is the bottom of the scheduling/planning hierarchy. It translates plans into events . Copyright c 2001 Stanley B. Gershwin. All rights reserved. 4 Definitions Control Paradigm System State Control Noise Observations This is the general paradigm for control theory and engineering. Copyright c 2001 Stanley B. Gershwin. All rights reserved. 5 Definitions Control Paradigm In a factory, State: distribution of inventory, repair/failure states of machines, etc. Control: move a part to a machine and start operation; begin preventive maintenance, etc. Noise: machine failures, change in demand, etc. Copyright c 2001 Stanley B. Gershwin. All rights reserved. 6
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Definitions Release and Dispatch Release: Authorizing a job for production, or allowing a raw part onto the factory floor. Dispatch: Moving a part into a workstation or machine. Release is more important than dispatch. That is, improving release has more impact than improving dispatch, if both are reasonable. (Wein observation.) Copyright c 2001 Stanley B. Gershwin. All rights reserved. 7 Definitions Requirements Scheduling systems or methods should . .. deliver good factory performance. compute decisions quickly, in response to changing conditions. Copyright c 2001 Stanley B. Gershwin. All rights reserved. 8 Performance Goals To minimize inventory and backlog. To maximize probability that customers are satisfied. To maximize predictability (ie, minimize performance variability). Copyright c 2001 Stanley B. Gershwin. All rights reserved. 9
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Goals For MTO To meet delivery promises. To make delivery promises that are both soon and reliable . For MTS to have FG available when customers arrive; and to have minimal FG inventory. Copyright c 2001 Stanley B. Gershwin. All rights reserved. 10 Performance Goals Objective of Scheduling t Cumulative Production and Demand earliness surplus x(t) production P(t) demand D(t) Objective is to keep cumulative production close to cumulative demand.
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This note was uploaded on 02/24/2012 for the course ENGINEERIN 2.852 taught by Professor Stanleyb.gershwin during the Spring '04 term at MIT.

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lecture8bw - SMA 6304 M2 Factory Planning and Scheduling...

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