A novel vibration-assisted magnetic abrasive polishing method for complex internal surface finishing

摘要

Components with complex internal surfaces are increasingly important for air or fluid flow applications in aerospace and automotive industries. Recently, as an emerging manufacturing technology, three dimensional (3D) additive manufacturing (AM) technology enables a one-step fabrication of these complex internal surfaces. Although 3D AM technology eliminates the need for complex assembly process, due to the rough surface finish and poor surface and sub-surface integrity, achieving a favourable surface condition is quite challenging. Therefore, a post-polishing process is essential for these 3D AM complex internal surfaces. This paper presents a novel vibration-assisted magnetic abrasive polishing (VAMAP) method to finish a kind of complex internal surface which has a double-layered tube structure fabricated by selective laser melt (SLM) Inconel 718. The set-up consists of a pair of magnets located externally to the workpiece as well as a diametrically magnetised cylindrical magnet located at the centre of the workpiece, along the axial direction. Owing to the magnetic field, the magnetic abrasives are attracted to the internal surface of the outer tube and external surface of the inner tube. Moreover, a relative movement is generated by a rotary motion or linear vibration between the workpiece and magnetic abrasives. Therefore, the surfaces between the inner and outer tubes were polished. The results show that the surface roughness was reduced from about 7 μm Ra to 0.5 μm Ra, and a uniform material removal was obtained on both of the polished surfaces.