A Study on Functions for Self-oiganized Layout and Autonomous Operation in Agile Manufacturing System

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In this study we investigate a manufacturing system with machining centers (MC) that can produce the variety of products with varying volume efficiently. A square arrayed layout of MCs is proposed with an auction based method for the operation as an extension of a serial-parallel layout. The given number of MCs, which is estimated for a given production plan are located on square grid points. Each MC holds toolsets for all processes of all products. An auction based method is applied to select an MC for the next processing of a pallet at the pallet changing station.By applying various bid types for the auction, it is observed that it is possible to generate a work flow in the system and/or to form a group of MCs producing a specific product when appropriate bid types are applied. We then developed a specialization algorithm which confines an MC to special processes of special products by deleting toolsets with low utilization and a generalization algorithm which relaxes the processing capability by adding toolsets when the utilization of an MC becomes too low or the queue at a PCS becomes too long. By these algorithms, the toolsets required for the system can be reduced considerably. To extend the function for the self organized layout, we consider an MC layout with sufficiently large number of MCs initially and then reduce MCs and toolsets considering their utilization. The proposed algorithm successfully applied yielding a layout which can produce the given total production volume with a given product mix. Algorithms for the specialization and generalization regarding to the toolsets are effectively applicable adapting the varying product mix, but a generalization algorithm adding MCs to cope with the increase of production volume is left to the further study.