Reactive scheduling in a make-to-order flexible job shop with re-entrant process and assembly: a mathematical programming approach |
| |
Authors: | Marta Castilho Gomes Ana Paula Barbosa-Póvoa Augusto Queiroz Novais |
| |
Affiliation: | 1. CESUR, Instituto Superior Técnico, Technical University of Lisbon , 1049-001 , Lisboa , Portugal marta.gomes@ist.utl.pt;3. CEG-IST, Instituto Superior Técnico, Technical University of Lisbon , 1049-001 , Lisboa , Portugal;4. UMOSE - Unit of Energy Systems Modelling and Optimization, National Laboratory of Energy and Geology , Est. Pa?o do Lumiar, 22, 1649-038 , Lisboa , Portugal |
| |
Abstract: | A mixed-integer linear programming model is presented for the scheduling of flexible job shops, a production mode characteristic of make-to-order industries. Re-entrant process (multiple visits to the same machine group) and a final assembly stage are simultaneously considered in the model. The formulation uses a continuous time representation and optimises an objective function that is a weighted sum of order earliness, order tardiness and in-process inventory. An algorithm for predictive-reactive scheduling is derived from the proposed model to deal with the arrival of new orders. This is illustrated with a realistic example based on data from the mould making industry. Different reactive scheduling scenarios, ranging from unchanged schedule to full re-scheduling, are optimally generated for order insertion in a predictive schedule. Since choosing the most suitable scenario requires balancing criteria of scheduling efficiency and stability, measures of schedule changes were computed for each re-scheduling solution. The short computational times obtained are promising regarding future application of this approach in the manufacturing environment studied. |
| |
Keywords: | reactive scheduling flexible job shop re-entrant process assembly mixed-integer linear programming |
|
|