ABSTRACT
Three-dimensional (3D) printing (3DP) is an umbrella term for a variety of additive manufacturing processes, where a 3D object is built up one layer at a time. The layers are programmed from a computer-aided design (CAD) model, which consists of many discrete two-dimensional (2D) layers to represent the object. A variety of methods fall under the umbrella of 3DP, including a variety of different material types, in a range of forms. Material jetting processes involve the selective dispensation of droplets of liquid material, normally through an ink-jet print-head, onto a substrate. These droplets then solidify to form the final part. Powder bed fusion relies on inputting thermal energy to melt selected cross-sections of a powdered material. These melted regions solidify upon cooling, whereas the remainder of the build volume remains as a powder surrounding the parts. Directed energy deposition also relies on the use of thermal energy.
