Batch scheduling with quality-based changeovers

Four of the main modeling frameworks for batch scheduling are compared and extended to include quality-based changeovers (QBC), a procedure in which the equipment cleaning operation in between batches can be avoided given that enough batches of the second product are performed in a row. QBC has been ignored up to this point in scheduling models. The frameworks considered are: State-Task Network (STN), Maximal State-Task Network (m-STN), Resource-Task Network (RTN), and Unit-Operation-Port-State-Superstructure (UOPSS). The results indicate the STN and m-STN formulations are limited for large-scale problems, the RTN is difficult to extend, but performs better as the number of changeovers increases, while the UOPSS is very intuitive and has a good performance for large scale problems. The use of lazy constraints for changeovers does not improve the computational efficiency. The inclusion of QBC does not add significant computational burden to the four frameworks.