The most fundamental concept to understand 3D printing is the process by which objects are built. The process is called additive manufacturing. 3 Conversely, the process that computer numeric control (CNC) machines use to form objects (starting with a block of material and cutaway parts to form the object) is called subtractive manufacturing. Both forms of manufacture use a Cartesian plot (X, Y, and Z axes) to position the hardware to execute the build. Thus, the mechanical movements for 3D printing are very similar to the mechanisms used in CNC machines.
In both cases, there are three axes of movement controlled by a computer, and capable of very high precision movement. Additive manufacturing has several forms or types that refer to the material used and the process used to take the material and form the object. However, they all use the same basic steps (called a workflow) to create the object. Let’s start from a raw idea and see how the idea is transformed into a physical object using additive manufacturing. The following lists the steps in the process at a high level. An object is formed using computer-aided design (CAD) software. The object is exported in a file format that contains the standard tessellation language for defining a 3D object with triangulated surfaces and vertices (called an .stl file).The resulting .stl file is split or sliced into layers, and a machine-level instruction file is created (called a .gcode file) using computer-aided manufacturing (CAM) software. The file contains instructions for controlling the axes, direction of travel, temperature of the hot end, and more. In addition, each layer is constructed as a map of traces (paths for the extruded filament) for filling in the object outline and interior. The printer uses its own software (firmware) to read the machine-level file and print the object one layer at a time. This software also supports operations for setting up and tuning the printer. This last step is where most 3D printing forms differ. That is, they vary slightly in the mechanism used and the materials used to form the object. However, all additive types use the same concept of taking an object and building it in layers.
