3D Printing
3D printing, also known as additive manufacturing, is a process used to create three-dimensional objects from a digital model by adding material layer-by-layer. The process begins with a virtual 3D representation of the object designed using computer-aided design (CAD). The model is then sliced into horizontal layers to convert it into an STL (standard tessellation language) file that is readable by the 3D printer. After transferring the data to the printer, the necessary settings are defined, and the printer produces the object one layer at a time, with each layer bonding and building upon the previous one. 3D printing enables the creation of highly intricate shapes and structures with high precision and repeatability, making it suitable for applications in aerospace, automotive, construction, fashion, food, jewelry, manufacturing, and medical sectors. Multiple techniques exist to print objects with diverse mechanical, thermal, and chemical properties from materials in molten, liquid, or powder states. Popular 3D printing technologies include VAT Polymerization, Fused Deposition Modeling, Powder Bed Fusion, and Jetting. For more information on how 3D printing can help minimize carbon footprints and contribute to sustainability, explore our 3D to 4D Printing for Added Sustainability Brochure.
Overview
Vat Polymerization
Vat polymerization uses photopolymerization to cure and solidify liquid polymer resin. Stereolithography (SL) was the first type of 3D printing developed and commercialized using this method. An SL printer uses mirrors positioned at the X-Y axes to direct a laser beam across a vat of resin to create a cross-section of the object. Digital light processing (DLP) uses a projector with an LCD screen or UV light source to flash light, creating each layer. This type of resin-based 3D printing is fast because an entire layer is exposed all at once. Masked stereolithography (MLA) uses an array of LEDs to shine UV light through a liquid crystal display (LCD) photomask.
Fused Deposition Modeling (FDM)
Fused deposition modeling (FDM), also called fused filament fabrication (FFF) or material extrusion, is the most common and inexpensive 3D printing technology. A spool of thermoplastic filament (e.g., PLA, ABS) is heated to its melting point and extruded through a nozzle onto a platform, where the molten material cools and solidifies. This technology is used in injection molding and modern plastic manufacturing for ready-to-use products.
Powder Bed Fusion
Powder bed fusion selectively cures polymer or metal powders with a thermal energy source to create a solid plastic or metal object. First, the powder is heated to a temperature just below its melting point. Then, a roller distributes a very thin layer of powder over the surface of the building bed before a laser passes over the layer to fuse it. Once a layer is completed, the powder bed sinks incrementally to form the next layer. Selective laser sintering (SLS) successively sinters polymer powder with a laser. Selective laser melting (SLM) involves fully melting metal powder instead of sintering it. Other forms of metal powder bed fusion include direct metal laser sintering (DMLS) and electron beam melting (EBM).
Jetting
Material jetting uses inkjet printer technology to add tiny droplets of photopolymers or wax onto a build plate. An ultraviolet (UV) light simultaneously cures the layers as they are printed. Material jetting (MJ) deposits material in a rapid, line-wise fashion, rather than point-wise. Therefore, multiple objects can be fabricated in a single line. Moreover, this method allows different materials to be printed in the same object. Drop-on-demand (DOD) 3D printing technology uses a set of two inkjets to deposit both the final object material and dissolvable support material simultaneously.