A novel chatter-resistant boring bar design with lattice structure and non-Newtonian fluid

Due to the low dynamic stiffness of long boring bars, chatter is a significant challenge for boring operations, resulting in poor surface finish and reduced tool life. Various passive chatter suppression techniques have been developed to enhance their dynamic performance, including the use of lattice structures and fluid-based solutions. The present study proposes a chatter-resistant boring bar design that integrates a lattice structure with a non-Newtonian fluid. Four different lattice structures and a shear-thickening fluid (STF) consisting of 15 wt% fumed silica dispersed in 85 wt% polyethylene glycol were considered during the design phase. The designed boring bars were fabricated using direct metal laser sintering (DMLS), followed by hot isostatic pressing (HIP). After adding the STF to the boring bars, their dynamic performance was evaluated using hammer impact tests, stability diagrams, and cutting tests on Ti-6Al-4 V specimens. The results showed that lattice structures with higher Maxwell numbers exhibited superior dynamic performance, particularly in terms of dynamic stiffness and stability, whereas lower numbers resulted in higher receptance. Adding STF to the boring bars introduced an additional energy dissipation mechanism, which significantly enhanced damping performance under dynamic loading conditions. Consequently, the proposed design reduced receptance by 64% and increased the stability limit by 102% compared to the full boring bar. The findings show that incorporating a lattice structure and a non-Newtonian fluid into boring bars can effectively suppress chatter during boring operations.