Abstract
A new investment planning method is proposed to determine purchase of suitable production equipment considering demand fluctuations by using portfolio for manufacturing systems consisted of CNC machine tools and jobs in this research. The portfolios are set to consider candidates of the purchasing production equipment for investment. Returns and risks considering demand fluctuations of the individual portfolios are required to select the best portfolio in the proposed investment planning method. The returns and the risks of the portfolios are calculated by using the returns and the risks of the purchasing individual production equipment for investment under assumptions that candidate production plans and probabilities that production plans correspond to demand have already been obtained. Profit of the manufacturing system is estimated in the cases where the production plans are carried out by using the purchased production equipment and existing that in order to calculate the returns and the risks of the purchasing individual production equipment.
