A New Approach to the Automatic Design of FMS Through a Simple but Effective Forecast of Production Needs

Summary

This paper describes a Configuration System which evaluates the manufacturing needs of a given workpiece set and configures the appropriate FMS accordingly. The FMSs this system considers are composed of modular machining centres (MC) chosen among models differing in the machining cube size and in the spindle degrees of freedom.

The system goals are: first to find out the MC model capable of producing the desired workpieces in the most efficient way and, then, to configure the FMS and to estimate the process plan characteristics (plan time, fixturing needs, number of tools ….). In other terms, the proposed system tries to develop the FMSs after having generated and evaluated the characteristics of the process plans each MC model would perform with the given workpiece set.

This is accomplished by using a simplified CAPP, implemented on a lisp-machine, which is based on a symbolic description of the work pieces and of the MC models. The workpieces are approximated to their enveloping parallelepipeds and the system only considers their size, their shape and the position of each machining zone. MC models are described in terms of capability to contain pieces and to reach the machining zones. A crucial point of this work has been to develop a simple user interface to quickly describe the parts being machined.