Swift feedback and immediate error control using a lightweight simulation approach – A case study of the digital-twin-in-the-loop for machining thin-wall structures

Abstract

The field of Digital Twins is rapidly growing, with an emerging trend of using virtual representations to directly control process-related errors in manufacturing operations. This paper introduces the Digital-Twin-in-the-Loop that uniquely integrates the Digital Twin (DT) into the direct feedback loop of a notoriously error-prone machining operation of low-rigidity structures. The proposed approach bypasses the need for post-process workpiece measurements by utilizing the twin to estimate 3D deformations caused by machining forces and correcting the toolpath automatically. For the first time, a fast and process-oriented simulation method, based on a mass-spring-lattice model for “on-the-fly” monitoring of workpiece deflections, as well as a comparative scaling method are presented as the backbone of the Digital-Twin. As a case study an end-milling operation is considered, focusing on the correction of the toolpath to improve the surface profile of low-stiffness components which are prone to dimensional errors. Experimental results show that the proposed method significantly improves the geometrical accuracy of the machined surface with a good repeatability, reducing errors by 78.96%. This establishes the Digital-Twin-in-the-Loop as a relevant tool for the implementation of time-efficient machining environments, while maintaining rigorous accuracy through in-process monitoring.