Materials and Processes
The consumer-grade 3D printers you saw in the first video all printed with thermoplastic feedstock. Some industrial-grade printers print with thermoplastic as well. They're just able to do a lot more with it. Notice anything new and interesting about the traffic cone being printed by a Makerbot Replicator 2X? You got it! It's printing two colors: red and black. If you look at the top, you'll notice two lines of feedstock being used. The printer alternates between colors as needed.
This type of printing is technically called Extrusion Deposition, or more specifically Fused Deposition Modeling (FDM). An object is produced by extruding small beads of material which harden immediately to form layers.
We just jumped from a printer costing a couple thousand dollars to one that costs a couple hundred thousand. This Connex500 Polyjet printer can print with multiple types of thermoplastics. It cures the material using UV light. The platform lowers one thousandth of an inch with each pass of the printer head. It can print objects with moving parts by using two materials, a build material and a support material. The support material is removed after printing to allow integrated parts to move. Notice all of the applications for multi-material printing.
Now we move from Fused Deposition Modeling or FDM to Granular Materials Binding. Selective Laser Sintering or SLS uses a laser to sinter powdered material (typically metal), binding the material together to create a solid structure. The process involves a layer of powder distributed across the printing platform, lasers sinter the powder precisely according to the digital 3D blueprint, another layer of powder is added, more laser sintering, layer after layer is added and sintered as the printing platform is lowered incrementally until the object is finished. Once finished the block of powder material is removed and the printed object is excavated from its center.
Selective Laser Melting or SLM, is a similar process to SLS, except in this case, the powder is heated to melting. In SLS the sintering heats material without actually melting it. With SLM the material is melted by the lasers. Here SLM was used to manufacture a metal propeller. Electron Beam Melting, or EBM, gets hotter still. EBM technology manufactures parts by melting metal powder layer by layer with an electron beam in a high vacuum. Unlike sintering techniques used in SLS, parts produced by the melting techniques of EBM and SLM are fully dense, void-free, and extremely strong. Here EBM is used to create titanium mesh that's used in medical reconstructive surgery.
Our next 3D Printing process is Lamination. This technique was developed by the mCor company which uses standard copy paper. Sheets of paper are glued together a layer at a time, with each layer being precisely cut according to the digital 3D blueprint. When finished the final model is excavated from the center of the paper. This process also allows for colors to be added as an object is being printed using standard printer ink producing a lifelike model.
The final 3D Printing process is Photopolymerization, which utilizes stereolithography to produce a solid model from a liquid polymer using UV light. The most common of these techniques is called Digital Light Processing or DLP. With this technique the printing platform is dipped into a liquid polymer, where UV light solidifies portions of the polymer on the platform. Each dip adds another layer to the object. Here, the technique is used to manufacture custom ear molds.
The Peachy Printer is a kickstarter project which claims to be the first $100 3D printer. This Peachy Printer utilizes the sound output port of your computer to create small printed objects using the DLP technique.
In the next video, we'll look at all the ways 3D printers are being used.