Development and Implementation of Modular Turning Dynamometer with Miniature Load Cell ^†

This study presents the design, development, and implementation of a novel modular three-axis cutting force measurement system for turning lathes. The system employs miniature load cells in an innovative two-channel slotted dynamometer structure, offering a cost-effective and compact alternative to conventional dynamometers. The primary structure utilizes a cantilever concept, in which cutting forces induce deformation, compressing strategically positioned load cells. A 300 kgf load cell measures the main cutting force, while a 100 kgf load cell detects the feed force. Additionally, a 20 kgf load cell measures the radial force through a sliding tool holder mechanism. Finite element analysis was employed to optimize the dynamometer’s parameters, striking a balance between maximum deflection and structural integrity. The optimized design achieved a safety factor of 4.377, with maximum deflections of 8.81 µm and 9.89 µm for the main cutting and feed force measurements, respectively. Static calibration of the load cells demonstrated robust correlations between voltage and force, with the coefficient of determination (R²) values exceeding 0.999. The system’s precision was evaluated through cutting experiments on mild steel of varying depths (0.5, 0.75, 1.0 mm) and feed rates (0.105, 0.150, 0.210 mm/rev). The experimental results indicate that the main cutting force consistently exceeded feed and radial forces across all conditions. The system exhibited high precision, with relative standard deviation (RSD) percentages below 5% on average and not exceeding 7.5% in individual experiments. This modular dynamometer design offers a flexible, precise, and cost-effective solution for cutting force measurement in turning operations. Its modularity facilitates easy maintenance and adaptation to various cutting conditions, rendering the developed modular turning dynamometer suitable for both research and industrial applications.