APPLYING PRECEDENCE RELATIONSHIPS AND CAD/CAM SIMULATION IN TIME-BASED OPTIMIZATION OF PROCESS PLANNING

Optimization of process planning belongs to the group of combinatorial optimization problems which at the macro and micro level consists of the selection of machining operations, definition of sequences of machining operations and their grouping into processes, selection of manufacturing resources, machining parameters and strategies. The objective function used for evaluating process plans is mostly defined by manufacturing cost, manufacturing time, surface quality and surface accuracy. The main goal of this research refers to the process planning and optimization of manufacturing time by applying precedence relationships among machining operations, as well as the simulation technique within the CAD/CAM system. The precedence relationships are defined on the basis of dimensional, geometric, technological and economical precedence constraints. Based on these rules, precedence matrices for determining operation sequence for the given shaft part are formed, and afterwards, machining operations are grouped into appropriate processes. For the given rational variants of process plans, a simulation of machining process is performed within the Catia software system. The obtained output is the best variant of process plan for the shaft part on the basis of manufacturing time as the adopted objective function.