Damping investigation in boring bar using hybrid copper-zinc particles

Particle damping is one of the promising damping techniques in effectively suppressing chatter in boring process. In earlier studies, granular particles are packed with the single particle type used to suppress chatter. This paper attempts at a novel hybrid approach in particle damping to increase the effectiveness of chatter suppression and enhance the machining stability. In this hybrid approach, Copper and Zinc particles are used together in equal proportion for packing inside the boring bar. The study finds this combined packing significantly improves the damping characteristic compared to the unmodified boring bar and also bar packed with single (Cu or Zn) particle type. The assessment benchmarks were the dynamic characteristics, modal analysis, damping ratio, logarithmic decrement and resonance gap of the machining system, as well as the displacement amplitude of the boring bar and the surface roughness of the work piece. The displacement amplitude of the boring bar and the surface roughness of the work piece in the combined packing case are reduced by 55% and 80% respectively when it is compared to the unmodified case.