Fuzzy Control of Spindle Torque in High-Speed Milling Processes

Torque control through feed rate and spindle speed manipulation can produce significant economic benefits for machining processes by reducing the cycle time. This paper focuses on the design and implementation of a fuzzy-logic-based torque control system, embedded in an open architecture computer numerical control (CNC), in order to provide an optimization function for the material removal rate. The control system adjusts the feed rate and spindle speed simultaneously as needed, to regulate the cutting torque using the CNC’s own resources without requiring additional hardware overhead. The control system consists of a two inputs (i.e., torque error and change of error) -two outputs (i.e., the feed rate and spindle speed increment) fuzzy controller, which are embedded within the kernel of a standard open control. Two approaches are tested and their performance is assessed using several performance measurements. These approaches are the two inputs-two outputs for the fuzzy controller and a single-output fuzzy controller (i.e., only feed rate modification). The results demonstrate that the proposed control strategy provides better accuracy, and machining cycle time than the others, thus increasing the metal removal rate.