The Process
The process of 3D printing begins by creating a virtual model of what you want to make using a 3D Modeling software. Some common software are AutoCAD, Blender, and SketchUp. This virtual model is called a Computer Aided Design, or CAD, file. After the design is finished, the CAD file is sent to a 3D Printer in the form of a .stl, .obj, or .VRML file . The 3D Printing hardware slices the design into 2D layers less than a millimeter thick. The 3D Printer then prints out the 3D object one layer at a time, building it from the bottom up.
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3D Printing Methods
There are many techniques by which a 3D object can be created. There are six that I think are particularly notable. Hod Lipson and Melba Kurman are the authors of Fabricated: The New World of 3D Printing. I will use their idea and separate the techniques of 3D printing into two groups: Printers that bind raw materials together, and printers that deposit raw materials in layers.
Printers That Bind
Stereolithography (SLA) - SLA was invented by Charles Hull in 1983. This method of 3D printing uses a liquid polymer or resin, and a laser to create 3D objects. A laser traces out the first layer of the 3D creation from the sliced CAD file onto the surface of the polymer or resin. The resin or polymer hardens when in contact with laser light. Then a piston moves the vat of liquid down less than a millimeter, while a sweeper puts a thin layer of resin or polymer on top of the first layer. The laser traces out the next layer. This process repeats until the object is complete.
Selective Laser Sintering (SLS) - SLS was invented in the 1980’s by Carl Deckard and Joseph Beaman. SLS is very similar to Stereolithography, except that it uses powder, not liquid, material. It uses the same process as SLA as well. A laser traces one layer at a time, and a sweeper applies more powder in between layers. SLS can use powdered metal, nylon, ceramic, glass and more. The variety of materials makes this method popular for creating customized products. Three Dimensional Printing (3DP) - It was developed in the late 1980’s by Paul Williams and Professor Eli Sachs. 3DP uses a process in which a print head squeezes adhesive or glue onto powdered material. After the first layer is completed, a sweeper adds more powder on top. Printers that use this technique don’t use a laser, can print in multiple colors at once, and can use a variety of materials, including powdered metal, clay, glass, sawdust, and ground up bones. This makes 3DP well liked among home users and hobbyists. |
Printers That Deposit
Fused Deposition Modeling (FDM) - The method was first developed in 1989 by Scott Crump, who later co-founded Stratasys Inc. 3D printers that use FDM build objects layer upon layer by melting a plastic filament and extruding it out of a print head. The print head lays down the first layer of the object from the sliced CAD file. Then the build platform moves down a tiny bit so the print head can lay down the next layer. This process continues until the design is complete. Another way a product can be produced using FDM is where the print head moves up and down and the build platform is stationary. At the moment, FDM printers use plastic filament wound on spools. This technique is popular for home users and hobbyists, and can be found in stores like Staples and Best Buy.
MultiJet Printing (MJP) - Invented in 1996 by 3D Systems, one of the largest AM organizations today. This method is similar to FDM; they both use print heads. Instead of melting and extruding plastic filaments, a UV curable resin or polymer is jetted onto a build platform, then is immediately cured by a UV light. MultiJet Printers can print in multiple colors at once, unlike most 3D Printers. Laminated Object Manufacturing (LOM) - It was developed in the late 1980’s to the early 1990’s by Michael Feygin and Sung Sik Pak of Helisys Inc. LOM doesn’t use a print head like FDM or MJP. Instead, LOM printers laminate thins sheets of adhesive paper, plastic, or metal together to create 3D objects. First, a computer controlled knife or laser cuts out the first layer of the object from the adhesive material. The excess material is taken away, and a new sheet is added on top. The next layer is cut out, then is fused to the layer below it with heat and pressure. This continues until your creation is finished. |
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