In this paper, we propose a method that uses a 3D scanner to efficiently turn a large backup roll weighing 50 60 –t from a free forged material. The material was prepared through free forging on a 17,000-t press; the machiningallowance was large and the distribution was uneven. Previously, skilled workers visually checked the shape of thematerial and manually performed roughing, which is a bottleneck in which machining defects often occur.
In this study, a 3D shape model was created through 3D scanning of the procedure to determine the centerline ofthe workpiece and create an efficient tool path for CNC rough turning. The proposed method was applied to fourproducts; the machining time was reduced by 35.7%, and no machining defects occurred thus far. The proposedmethod can be used to process not only backup rolls but also large rotating parts such as turbine shafts.