Key factors and developmental directions with regard to metal additive manufacturing

Metal additive manufacturing is a new type of material-forming technology characterized by its short process and near net shape. Equipment, material and process are critical factors which serve as the supporter, key, and foundation respectively in terms of the development of this technology. In this paper, the characteristics of the equipment, material, and process of the different representative technologies were summarized. The relations among metal additive manufacturing equipment, manufacturing material, and manufacturing process as well as their roles in the metal additive manufacturing technology were analyzed. The research status of the raw material supply system, forming system, and control system were reviewed. The typical microstructure and mechanical properties of metal additive manufacturing materials, such as titanium alloy, nickel alloy, aluminum alloy, and steel, were summarized. The effects of the manufacturing process parameters on residual stress, porosity, accuracy, and microstructure were discussed. Problems associated with the manufacturing equipment, such as high cost, limited forming size, and low forming efficiency were discussed along with the problems associated with the material, such as high production cost and poor applicability. Furthermore, problems associated with the metal additive manufacturing process, such as difficult matching of process parameters and severe thermal accumulation, were elaborated as well. Future developmental goals in metal additive manufacturing include: (a) reducing the cost of manufacturing equipment and material, (b) expanding the range of product forming size, (c) improving the product printing accuracy and forming efficiency, (d) expanding the types and application scope of metal additive manufacturing material, (e) reducing the difficulty in the matching of process parameters, (f) improving product quality and comprehensive performance, and (g) developing new types of metal additive manufacturing technologies.