THE 3D PRINTING PROCESS
3D printing is an additive process, which means that the object is constructed by adding material in layers. This is in contrast to “subtractive” manufacturing, through which an object is constructed by cutting or machining raw material into a desired shape.
Almost all consumer 3D printers use a type of plastic to create objects. The two most popular plastics are Acrylonitrile Butadiene Styrene (ABS), which is also used to make Lego and is chemical-based, and Polylactic Acid (PLA), which is derived from natural sources, such as corn or sugarcane. PLA tends to be stiffer than ABS. Whichever plastic the 3D printer uses – some can actually use both – the raw material comes in the form of filament, usually 1.75mm or 3mm in width, which is stored on a spool attached to the 3D printer.
When the filament is attached to the printer, it is fed through the print head. The print head contains a heated tube that the filament passes through, heating it and liquefying it before it is extruded by the print nozzle. The liquid plastic is then deposited as ultra-fine lines generally about 100 microns thick, or roughly 0.1mm, which quickly solidifies and fuses to build up layers. Some printers can deposit layers as thin as 16 microns, or 0.016mm.
To make the object 3D, the print head needs to be able to move in multiple dimensions. Many printers use a gantry-type system where the print head is attached to a metal frame, letting it move both horizontally and vertically. The print bed will then move up and down to add a third dimension. In some printers the print head can move in all three dimensions. Print jobs can take minutes, hours or even days for more complicated objects.