Abrasive Delivery During Magnetic Field-Assisted Internal Finishing of Complex Additively-Manufactured Channels

Abstract To reduce or eliminate waste, the near-net-shape geometries produced using additive manufacturing (AM) should be surface finished with minimal material removal. A major challenge in internal polishing of complex AM channels is to deliver the polishing tool and abrasive deep within these channels to smoothly finish them. One approach is the use of magnetic field-assisted finishing (MAF) to securely deliver a polishing tool and abrasive and finish surfaces with minimal material removal deep within complex channels made using AM. This study presents the development of a new hybrid polishing tool that can be manipulated within channels by magnetic force. This hybrid tool securely carries abrasive and delivers it to targeted machining locations within a channel, using either a fixed or loose abrasive phase as appropriate. These tools are made of magnetic particles, abrasive particles, and water-soluble binder, and can be fabricated in a variety of geometries matching desired workpiece geometries (e.g., planar, round, oval, D-shaped) to meet various industry needs. First, the effects of tool composition on its behavior inside a channel are experimentally characterized. Second, the relationship between the tool behavior—especially the abrasive delivery inside the channels—and material-removal characteristics are clarified by the internal polishing of 316L stainless steel tubes made using directed energy deposition (DED).