ADVANCED MATERIALS & PROCESSES | MARCH 2026 18 Additive manufacturing (AM) has long been promoted as a material-efficient alternative to conventional subtractive processes. The underlying sustainability prospects of AM are increasingly being explored as the field matures and industrial adoption accelerates. Feedstock production, in the form of metal powders, wires, pellets, or filaments, often dominates both the economic cost and environ- mental footprint of AM processes and the parts produced. This reality, coupled with growing volumes of metallic and polymeric manufacturing waste, has prompted renewed interest in material “upcycling”—the transformation of manufacturing scrap, process by-products, or post-consumer waste into high-value feedstock suitable for AM. WHY UPCYCLING MATTERS IN AM Unlike conventional recycling, which typically involves energy-intensive remelting and may degrade material value, upcycling aims to retain or enhance material value while minimizing energy, emis- sions, and processing steps. This article reviews the state of the art in upcycling strategies across AM modalities, STATE OF THE ART IN MATERIAL UPCYCLING FOR ADDITIVE MANUFACTURING From machining scrap to recycled powders and polymers, upcycling is rapidly moving into mainstream AM—an overview of the processes, current state, impacts, and future view. Sweta Baruah, Knoxville, Tennessee composition are locally available or where recovery can be built into the AM workflow. Machining and Manufacturing Scrap. Metal chips generated during the machining of aerospace-grade aluminum, titanium, and steel alloys represent a high-volume, compositionally controlled waste stream. Traditionally remelted or downcycled, these chips have gained attention as direct feedstock candidates for solid-state and extrusion-based AM processes. highlighting pathways that are industrially relevant today and those likely to scale up in the near future, particularly for metallic systems where feedstock cost, qualification, and supply-chain resilience are key drivers. SOURCES OF WASTE AND UNTAPPED FEEDSTOCK Across AM, upcycling opportunities emerge wherever high volumes of waste streams with a fairly well-known Fig. 1 — Overview of material upcycling pathways enabling circularity in additive manufacturing. Diverse waste streams are converted into AM-compatible feedstocks that support solid-state, melt-based, and extrusion-based processes within a closed-loop manufacturing framework.
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