ORIGINAL ARTICLE A metal additive manufacturing method: semi-solid metal extrusion and deposition Amin Jabbari 1 & Karen Abrinia 1 Received: 20 April 2017 /Accepted: 11 September 2017 # Springer-Verlag London Ltd. 2017 Abstract Different existing metal additive manufacturing (AM) processes have many shortcomings and a lot of activi- ties are centered on improving the final printed metal product. A new method of metal additive manufacturing has been pro- posed in this paper. Unlike most of the metal additive manufacturing processes, it does not use metal powder. The proposed method utilizes semi-solid metal (SSM) forming combined with deposition process as used in the most com- mon additive manufacturing process for polymers. SSM forming is a promising near net shape technology with several advantages, such as being a porosity-free product and having reduced shrinkage, controlled microstructure, and excellent mechanical performance. Implementation of this technology in metallic additive manufacturing improves the mechanical properties and cost savings. Complicated time-dependent be- havior of SSM makes it a challenging issue to utilize in addi- tive manufacturing. A wire feedstock as a metallic filament was employed for the proposed process. However, some ma- terial preparations were necessary to get the desired rheolog- ical properties at the deposition head. In this study, the strain- induced melt-activated (SIMA) process was applied on a low- melting-temperature Sn-Pb alloy to obtain the desired globular feedstock microstructure. Then, preconditioned wire was fed in a thixo-extruder, which was designed and built for the pro- posed method in this research. A semi-melted alloy was de- posited on the moving substrate to build a metallic part layer by layer. Various parameters of SIMA and thixo-extrusion processes, including wire thermomechanical cycle, feed rate, solid fraction, nozzle and chamber geometry, and others, were examined experimentally, and a sustainable semi-solid metal extrusion and deposition (SSMED) process was achieved. Finally, an acceptable metallurgical layer bonding was obtain- ed at the interface of the deposited layers, with good mechan- ical properties of the fabricated parts. The new proposed meth- od seems to have great potentials for metal additive manufacturing parts. Keywords 3D printing . Semi-solid alloy . Wire thixo-extruder . Metallic filament 1 Introduction Additive manufacturing is a technology that aims to reduce part costs by decreasing the material wastage and time to market [1]. It is one of the most growing and developing technologies in the recent years. The process includes layer- based manufacturing where the material is added in a layer- by-layer fashion to build the required product. AM could pres- ent better flexibility in geometry and great potential savings in time and cost [2]. There exist many different methods for this type of manufacturing for various materials such as polymers, ceramics, metals, and composites [3–8]. Complex industrial parts could be manufactured directly from CAD data using metallic additive manufacturing (AM). Up to date, there are three primary feedstock process forms for metal AM: (a) powder-bed methods, (b) powder-fed methods, (c) wire-fed methods; the first two uses laser or electron beam energy source for sintering/melting of the metal powder and the last one uses the same sources to melt a wire [6]. * Karen Abrinia cabrinia@ut.ac.ir Amin Jabbari a.jabbari@ut.ac.ir 1 School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran Int J Adv Manuf Technol DOI 10.1007/s00170-017-1058-7