Production cost and tool reliabilities: The machining cycle influence in flexible plants

Abstract This paper aims to show how to quickly and efficiently evaluate the productivity and the related costs of a complex manufacturing plant (FMS), when the properties of tools must be regarded as probabilistic ones. In this field, the present study offers an analytical procedure that allows the calculation of damaged workpieces and broken tools as a function of the system reliability, when linked cutting operations on the same workpiece are considered. The system performance was examined referring to different control policies, i.e. the on-line check of each cutting operation and the off-line control of the workpiece when its cutting cycle has been performed. An FMS of four identical machining centers was assumed to cut four types of workpieces using ten different kinds of tools. The cutting system was simulated for three different sets of values of the productive mix and different numbers of linkages. The results obtained from the simulation method are in good agreement with those offered by the suggested analytical technique of forecasting.