Design of a damped tool holder to enhance the cutting capacity of slender turning tools

Many turning operations, particularly internal machining, require slender tools whose high dynamic flexibility can induce self-excited vibrations, limiting their cutting capability. Traditional solutions rely on anti-vibration bars that incorporate a tuned mass damper, a suspended mass between viscoelastic elements, to attenuate tool vibrations and enhance process stability. However, their design complexity increases the costs, making manufacturers reluctant to adopt them and motivating the search for alternative solutions that enhance process stability without the need of specialised bars. This study presents a novel strategy based on inducing modal coupling between the tool and the machine components, enabling tool damping without relying on anti-vibration tools. To implement this approach, a damped tool holder has been developed that can be easily integrated into existing machines. This device is designed to generate a frequency and damping controlled translational mode, aligned with the tool’s bending mode, enforcing the desired mode coupling to damp the tool. It operates over a wide frequency range, with tuning capability via a variable-stiffness spring, making it suitable for tools of different lengths and diameters. Its design and dimensioning follow the optimal tuning formulation outlined in this work, aimed at maximising process stability, and are supported by simulation tools. Both finite element simulations and stability lobe diagrams have been performed to optimise the dynamic response of the device and evaluate its impact on the process stability.