DETERMINATION OF AN OPTIMAL CONFIGURATION OF OPERATING POLICIES FOR DIRECT-INPUT-OUTPUT MANUFACTURING SYSTEMS USING THE TAGUCHI METHOD

Some modem manufacturing systems have workstations directly integrated with a centralized storage and handling system for work-in-process. W e consider a Direct-Input-Output manufacturing system(DIOMS) which has a number of machine centers placed along a built-in automated storage /retrieval system(AS/RS). The storage/retrieval(S/R) machine handles p arts placed on pallets for the machine centers located at either one o r both sides of the AS/RS. This paper investigates the operational asp ect of DIOMS by the Taguchi method. Four operating policies including input sequencing control. dispatching rule for the S/R machine, machin e center-based part type selection rule, and storage assignment policy are treated as design factors. For the performance characteristics, m ean flow time and throughput are adopted. The number of machine center s, the number of part types, demand rate, processing time and the rate of each part type. vertical and horizontal speed of the S/R machine, and the size of a local buffer in the machine centers am considered as noise factors in generating various DIOMS environments. A robust desi gn experiment with inner and outer orthogonal arrays are conducted by computer simulation, and an optimal configuration of operating policie s is presented which consists of a combination of the level of each de sign factor. The validity of the optimal configuration is investigated by comparing its SN ratios with those obtained by an experiment with full factorial designs.