Magnetically driven internal finishing of stainless steel tubes by a novel electrostatic flocking and drum-shaped polishing tool

High-quality internal surface finishing is essential for components used in critical industries such as aerospace and medical devices. Compared to conventional magnetic abrasive finishing (MAF), magnetically driven internal finishing (MDIF) represents a more flexible, controllable, and promising processing technology. However, the MDIF technique is constrained by the utilization of fixed-abrasive tools, which limit the attainable surface roughness to above 100 nm Ra. This study proposes a new MDIF tool that uses electrostatic flocking to coat a specially designed drum magnet with a flocking layer. Compared to manual flocking, this technique can more easily build a more uniform and directional flocking layer, improving material removal efficiency. Experimental results demonstrate that this method can reduce the internal surface roughness Ra of 316L stainless steel tubes from an initial average of 265 nm to 29 nm within 10 minutes, improving surface quality by over 89 %. Furthermore, repeatability experiments have shown tool performance to be highly consistent. Experiments on a larger-diameter tube verified the tool's dimensional versatility. This novel approach markedly advances the MDIF process and attains high efficiency nanofinishing, demonstrating substantial potential for precision internal finishing applications in high-demand industries.