Rework and postponement: a comparison of bottling strategies

This paper presents the results of a case study in a batch production facility for biological vaccines. The problem considered is that of finding the best bottling strategy for produced batches. A batch can be bottled directly after production, after positive intermediate test results, or after positive final test results. Strategies that start the bottling process quickly after production, have the advantages of a low capacity requirement for production tanks and of a small throughput time if all test results are positive. However, a production batch can only be reworked as long as it has not been bottled. So fast bottling reduces the possibilities for rework and therefore reduces the production yield. We present performance measures for comparing the different strategies and derive closed-form expressions for them. We illustrate the results obtained for the considered case.