The development of inventory lot-sizing model and production and inventory planning simulation models for remanufacturing systems

2017-02-02T02:47:12Z (GMT) by Andrew Munot, Magdalene
Recently, remanufacturing has become an important production activity in many companies; a phenomenon that results from the increasingly strict environmental regulations, growing customer awareness of green environment and economical benefit. Nevertheless, remanufacturing systems remain uncertain and complex in nature due to the existence of several unique characteristics. In this context, this thesis provides a significant contribution to advancing the current knowledge on remanufacturing through the development and analysis of four valuable decision-making tools for remanufacturing. The first decision-making tool is developed to address inventory lot-sizing problems in a hybrid remanufacturing-manufacturing system with varying remanufacturing fractions. The existing inventory lot-sizing models mainly implement a constant remanufacturing lot-size, which results in delay of remanufacturing process, carryover of remanufacturable stocks after each remanufacturing process and storage of remanufacturable items over the entire manufacturing interval. Accordingly, a new integrated inventory lot-sizing model is developed, which implements variable remanufacturing lot-sizes to address the problems of varying remanufacturing fractions in a hybrid remanufacturing-manufacturing system. The new integrated inventory lot-sizing model is utilised to concurrently determine the optimal lot-sizes for remanufacturing, number of remanufacturing lots and lot-sizes for manufacturing. Case studies show that the new integrated inventory lot-sizing model leads to a cost saving when compared to a benchmark model that implements a constant remanufacturing lot-size. The second decision-making tool, an integrated production and inventory planning simulation model is developed to address a problem to determine the optimal remanufacturing policy for implementation in a remanufacture-to-stock system with varying inspection yields and availability of used products. Four-variants of the integrated production and inventory planning simulation models are developed and analysed, where different remanufacturing policies are examined for processing two different quality remanufacturable groups. Case studies show that for processing two different quality remanufacturable groups in a remanufacture-to-stock system with varying inspection yields and availability of used products, a policy which specifies simultaneous processing and utilising dedicated resources emerges as the optimal remanufacturing policy. By contrast, when resources are finite, a policy that specifies sequential processing and switching between the two quality remanufacturable groups to sustain production appears as the optimal remanufacturing policy. Unlike the second tool, the third decision-making tool is developed to address a problem to determine the optimal remanufacturing policy for implementation in a remanufacture-to-order system with varying inspection yields and availability of used products. Three-variants of the integrated production and inventory planning simulation models are developed and analysed, in which different remanufacturing policies are assessed for processing two different quality remanufacturable groups. Case studies show that for processing two different quality remanufacturable groups in a remanufacture-to-order system with varying inspection yields and availability of used products, a policy that specifies sequential processing and switching between the two quality remanufacturable groups to sustain production emerges as the optimal remanufacturing policy. Finally, the fourth decision-making tool is developed to address a problem to determine the optimal remanufacturing strategy for implementation in a remanufacturing system. Two-variants of the integrated production and inventory planning simulation models are developed and analysed, where different remanufacturing strategies are investigated for processing two different quality remanufacturable groups. Case studies show that for processing two different quality remanufacturable groups, a strategy that specifies carrying some finished products inventory at all times (i.e., a remanufacture-to-stock) emerges as the optimal remanufacturing strategy.