Batch splitting in an assembly scheduling environment

This paper presents mathematical models and algorithms for a production scheduling problem with batch splitting of assembly operations. The operation precedence is represented in an operations network, and the operations at any particular workcenter are split into suitable batch sizes on the available identical parallel processors for faster completion. The solution methodology comprises of a batch splitting algorithm followed by a batch scheduling algorithm. The batch splitting algorithm is developed based on a preemptive scheduling algorithm after incorporating non-zero setup times. The batch scheduling algorithm is based on a critical path algorithm for an operations network. The mathematical model also considers movesizes for batches which determine the threshold for the batch size that needs to be built up before it can be transferred for the successor operation. The computational results for different problem sizes show that the proposed solution scheme can satisfactorily solve this complex scheduling problem for cases where the standard solvers fail to generate solutions within practical time limits. Moreover, there is a significant reduction in makespan due to batch splitting.