A Concurrent Engineering approach to selective implementation of alternative processes

During the last decade, integration between design and manufacturing has shown to be a major competitive weapon and much research work has been carried out about considering at the product design stage production process issues. Most of the literature on such techniques focuses on integrating the design of a product and the design of its manufacturing processes, disregarding issues related to the design and management of the manufacturing system. Nonetheless, decisions taken at the product and process design stage could have an influence on typical production planning and control issues such as, for example, minimising lead times and maximising machine utilisation. Many research works show the advantage of a higher process flexibility, in terms of machine utilisation, manufacturing lead time, inventory level, and the like (see, for example, Tsubone and Horikawa, The International Journal of Flexible Manufacturing Systems 11 (1999) 83 or Ferreira and Wysk, Journal of Manufacturing System 19 (2001)), but developing alternative machine possibility has a cost that is not negligible (International Journal of Production Economics 48 (1997) 237). Therefore, guidelines are needed for identifying for what items and for which operations to develop alternative processes. In this paper, the relationship between alternative processes availability and manufacturing system performances are investigated, showing that the advantage of additional alternative process decreases as the number of alternatives increases, and that given a certain number of alternative processes developed, there is a strong difference in performances depending on what alternative processes have been implemented. Then a new procedure is presented for guiding in selecting for which operations to implement alternative processes in order to maximise the flexibility advantages limiting the implementation cost. The proposed procedure is then tested, under different operating conditions, against a practical rule by means of a simulation model