As a startup company all of our technology choices are crucial but our choice of printer technology has been the most significant of all. Although 3D printing has been around since the 1980's, no particular technology has emerged as the standard and a variety of options are available. We chose Objet Geometries' Polyjet technology for its optimum balance of high resolution, speed, material qualities and price.
Patented by Objet and introduced in 2000, Polyjet technolgy takes ink jet printing into three dimensions. By simultaneously jetting build and support material from hundreds of heads moving across the build tray, it creates layers approximately 1/1000th of an inch high. The heads are immediately followed by a curing UV light so that, layer by layer, a fully polymerized object is built.
With Polyjet technology we can additively fabricate objects with accurate details down to 0.0039-0.0078 in (0.1-0.2mm). Walls can therefore be as thin as 0.1-0.2mm. However, for best results, we recommend only attempting to print details as small as 0.1mm if they are isolated. Parts closer than 0.5mm risk running together. Overall the object can be as large as 11.58 x 7.58 x 5.85 in.
Our standard print material is Objet's VeroWhitePlus, an acrylic polymer with properties rather in between ABS and PVC. (See a table of standard properties below.) VeroWhitePlus is suitable for most applications but Blue, Gray and Black are also available. In addition a polypropylene-like material, DurusWhite, is also available for more demanding applications.
At first glance it seems counterintuitive that 3D printing should require additional material for support. Isn't the beauty of the technology that you build from scratch, only using the material you need? Well, yes and no.
Independent of the technology, printing in 3d requires building up from the bottom in layers. In order to attain high resolution, these layers are made as thin as possible - in the case of Polyjet technology, 0.001 inch. It can be compared to building a house with layers of paper. To continue this analogy, imagine that this house has a cantilevered balcony. When we first encounter this balcony in our construction we will only be building the first paper thin layer on the bottom of the balcony. Clearly this will not support itself.
This problem is solved by planning ahead and building layers of support material - from the ground up - so that when we reach the balcony we have a ready made surface upon which we lay our first and subsequent layers of build material. When construction is complete, the support material is removed.
There are a number of different approaches to both support material and how it is removed. For example, some technologies use build material for support structures. Others require soaking in a chemical bath, post build, to remove supports. Polyjet techology uses a UV-cured gel-like material to build supports. Immediately after completion of the build, this material can be removed by hand or water jet.