Recycling metal cutting chips into a consolidated deposition with friction surfacing

Abstract

The objective of this research is to evaluate the feasibility of using metal cutting chips as a feedstock in solid-state metal additive manufacturing, with friction surfacing used as a demonstrator. To date, the recycling of metal cutting chips is an energy-intensive process. Compared to recycling processes that melt down metal chips, friction surfacing is a solid-state process, which should reduce the overall embodied energy needed to reuse the chips. While friction surfacing is primarily used for coating surfaces to improve their wear properties, it is also showing promising results as an additive manufacturing process for repair / remanufacturing features on large metal parts. Metal cutting chips of 316L stainless steel, produced by a milling operation, were pressed into hollow 304L stainless steel rods. The chip-filled rods were used as the [consumable] friction surfacing tools to deposit on 304L stainless steel substrates. The properties of the resultant deposits are analyzed and compared with deposits made by solid 304L and 316L tools, including deposition geometry, efficiency, process forces, and bond strength. Results indicate that a fully consolidated deposition can be created from the metal cutting chips using this process. Compared with a solid 304L tool, deposits made with metal chip-filled tools were narrower but thicker in the steady-state region when deposited with the same process parameters.