Fundamental study of fused-coating based metal additive manufacturing

Fused-coating based metal additive manufacturing (FCAM) is a newly established direct metal forming process. This method is characterized by deposition metal materials in a crucible and under the driving pressure the molten metal is extruded out from a special designed nozzle. Hence, dense metal parts with different kind of materials can be built on the moving substrate layer by layer. It provides a method to fabricate metal components with lower costs, clean and cheap materials compared with other AM processes. To study the feasibility of this new AM methodology, an experimental system with a molten metal stream generator, a fused-coating nozzle, a process monitor unit, an inert atmosphere protection unit and a temperature measurement unit has been established. In order to determine the proper parameters in the building process, a metal fused-coating heat transfer model analysis and experimental study is performed by using Sn63-37Pb alloy in building threedimensional components. The process parameters that may affect fabrication are molten and substrate temperature, layer thickness, the substrate-speed, the temperature of substrate, the distance between the nozzle and substrate and the pressure. Microscopy images were used to investigate the metallurgical bonding between layers. The influence of different parameters on the layer thickness and width was studied quantitatively. At last, the optimal parameter was used to fabricate complex metal parts to demonstrate the feasibility of this new technology compared with other AM methods.