  In many manufacturing processes, batch processing is frequently needed for
capacity reasons. This applies both to parallel and serial batching. However,
while the serial batch processing is largely studied in the literature, as it
is related to the setup issues, the parallel batch processing is less
investigated. In parallel batching, the manufacturing facility (e.g., ovens for
burn-in operations) is able to accommodate, and process, several parts at the
same time and not to exploit such ability leads to a reduction in the capacity
of the manufacturing facility itself, which will be able to process less parts
per time unit. In this paper, the scheduling problem in batch processing
environments is considered. Specifically a column generation algorithm is
proposed for parallel batching in both single machine and parallel machine
layouts. Numerical results show that the proposed algorithm is able to achieve
good solutions in reasonable computation time due to the use of a new developed
lower bound much stronger than the literature available lower bounds.
