Continued from part 1
#2 – Polyjet 3D Printers are very similar to your office variety ink jet printers, in that they have a bank of print heads that lay down a pattern of photo-polymer resin, and a gel like support material, with a UV light on the print carriage that cures each layer on every pass.
They build a model in horizontal layers that are 6-12 ten thousandths of an inch (.0006″-.0012″) thick. The resolution on the X-Y plane on some of the machines is as high as 600 dots per inch (dpi). Due to the high resolution of the print heads and layer thickness, the surface quality, and dimensional accuracy are superb.
After the model is printed, the gel support material is blasted away with a water jet and then they are dipped in a solution to remove any residue. These are my models of choice, when I intend to make very accurate molds for casting, as they require a minimal amount of sanding before I can clear coat them to achieve a smooth, glossy surface.
On the Eden class machines like the one that I have access to, there are several materials available, with Durus Grey being the usual resin of choice, as it is a fairly hard and tough acrylic like material. With a 19.6″x 15.7″x 7.9″ build envelope (x-y-z axis respectfully), it has the capability to produce rather large parts, or multiple smaller parts in a single build.
Objet machines in the Connex family have the capability to print several different resins, and can create 14 different materials in the same print. They can also create up to 51 digital materials that have properties ranging from rubber like, to rigid in the same model, so there is no need to glue different parts together to simulate an injection molded multishot product.