Improving Quality in Flexible Manufacturing Systems: A Systems Approach

In this paper, a Markov chain model is introduced to study quality in flexible manufacturing systems with batch productions. To improve the quality performance in such systems, we introduce the notions of quality improvability and bottleneck sequence. A flexible system is improvable in terms of quality with respect to sequencing if there exists another sequence which renders better quality. In addition, we define quality bottleneck sequence as the one that impedes the product quality in the strongest manner, i.e., the sequence that leads to the worst quality among all possible sequences. To identify quality improvability and bottleneck sequences, we develop indicators only based on the data available on the factory floor. Numerical experiments show that these indicators provide correct identification in most cases, and can be used for quality improvement effectively. A case study at an automotive paint shop is introduced to illustrate the applicability of the method.