Laboratory and numerical investigation of cutting tool performance using a new small-scale linear cutting machine

Evaluation of the cutting and wear performance of cutting tools in full-face tunnel boring machines (TBMs) for soil and rock formations is critical for accurate project scheduling and cost estimation. The significant investment costs associated with mechanized tunneling necessitate comprehensive laboratory and numerical tests, such as linear cutting tests, to guide machine selection and cutterhead configuration. This study investigates the performance of cutting tools using a novel small-scale Linear Cutting Machine (LCM). To achieve this, a small-scale LCM was developed, and linear cutting tests were performed on nine rock specimens of varying geological origins. Each rock specimen measured 200 mm × 150 mm × 80 mm. The shear disk studied in this research is located 3.5 m from the center of the cutterhead. This shear disk travels a distance of 22 m with each rotation of the TBM cutterhead, considering the circumference of the circle. Based on the 1:10 scale conversion applied in this study, the constructed shear disk should also travel 2.2 m across the rock. Several cutting components are analyzed in linear cutting tests, including specific energy (SE), cutting coefficient (CC), and disk wear. Additionally, all laboratory tests were numerically modeled using the finite element method under identical boundary conditions. Results indicated that Basalt-1, due to its high porosity, required the highest specific energy, while softer rocks like travertine-1 exhibited the lowest. Also, the cutting coefficient increased with penetration depth, emphasizing its role in controlling friction and optimizing disc bearing performance. Fossiliferous limestone demonstrated the highest cutting coefficient due to its fine-grained structure and high friction. Identifying penetration depths that maximize excavation rates while minimizing forces, this study enhanced excavation efficiency and tool longevity.