Production lot-sizing decision making considering bottle-neck drift in multi-stage manufacturing system

Under a capacity constrained multi-product manufacturing system, the products are usually prepared and produced in lots. As a lot-sizing strategy is critical for effective production and high productivity, this encourages practical and research interest in the strategic batch sizing decision for a minimum procedure time in an order-to-delivery (OTD) operating environment. While the lot-sizing plan can be formed by studying the manufacturing parameters of the established bottleneck procedure, for a multi-stage manufacturing system, the bottleneck is not fixed and fluctuates with the production rate or batch size. This paper proposes a lot-sizing strategy to determine the optimal lot-size for each class of products taking bottleneck drifting into consideration. A queuing network analyser (QNA) method is employed to deal with the non-linear mixed integer programming model targeting at the total flow time minimization of the system. A practical case is presented and solved using the proposed method, and the results are validated with Flexsim, a simulation model.