On-line Scheduling Of Multi-Server Batch Operations

Batching jobs in a manufacturing system is a very common policy in most industries. Main reasons for batching are avoidance of setups and/or facilitation of material handling. Good examples of batch-wise production systems are ovens found in aircraft industry and in semiconductor manufacturing. These systems often consist of multiple machines of different types for the range and volumes of products that have to be handled. Building on earlier research in aircraft industry, where the process of hardening synthetic aircraft parts was studied, we propose a new heuristic for the dynamic scheduling of these types of systems. Our so-called look-ahead strategy bases its decision to schedule a job on a certain machine upon the availability of information on a limited number of near future arrivals. The new control strategy distinguishes itself from existing heuristics by an integral approach that involves all machines in the scheduling decision, instead of only considering idle machines. It is shown by an extensive series of simulation experiments that the new heuristic outperforms existing heuristics for most system configurations. Especially in case of complex systems, where multiple products have to be handled by different types of machines the new heuristic proves its value as a practical scheduling tool. Important insight is obtained with regard to the relation between the system configuration and its performance.