We consider a scheduling problem commonly observed in the metal working industry. We analyze a job shop
which is equipped with one batch processing machine (BPM), and several unit-capacity machines. Given a set of
jobs, their process routes, processing requirements, and size, the objective is to schedule the jobs such that the
makespan is minimized. The BPM can process a batch of jobs as long as the total batch size does not exceed the
machine capacity. The batch processing time is equal to the longest processing job in the batch. The problem
under study can be represented as Jm|batch|Cmax, using the three field notation. If no batches were to be formed,
the scheduling problem under study reduces to Jm||Cmax, which is known to be NP-hard. A network
representation of the problem using disjunctive and conjunctive arcs, and a Mixed-Integer Linear Programming
(MILP) are proposed to solve the problem. An experimental study was conducted to evaluate the proposed
mathematical formulation.
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