We have been using stereolithography (SLA) and FDM (fusion deposition modeling) for rapid prototyping for quite some time at Omnica. SLA is still the best method for large parts, but for most of the rapid prototyping we do, Fused Deposition Modeling, and more recently, Polymer-Jet 3D printing is what we use most often. The parts that these newer "additive manufacturing" methods produce, work quite well as accurate patterns for our urethane molding shop, "one- off" models, and in some cases, robust components.
In 2004 we purchased our first Stratasys FDM printer. It was costly, but there were so many advantages of owning one, we made the decision to invest in the relatively new process. In the past few years, these and other 3D printers have become much more affordable. We now have six rapid prototyping machines.
We recently added another Objet rapid prototyping system to our tool kit. It is an Object 30 Pro, a polyjet machine that can print up to eight different materials, including transparent and high-temperature photopolymers. There are other benefits our customers will realize from this new addition, and you can read about them here. We have other rapid prototyping machines and methods that help speed our development processes.
All five 3-D printers offer real speed and cost benefits to our customers.
The two refrigerator-sized FDM machines are two Elites, a 1200ES Dimension models made by Stratasys. They build parts layer by layer, with strands (0.005"-0.0013") of tough ABS plastic. Thickness of the layers depends on the build speed, but since the filaments are relatively coarse, parts that come directly from the FDM machines can be "cosmetically challenged". They are not quite smooth enough to be used as silicone mold patterns or finished prototypes with minimal post finishing. Useful applications are tool handles, custom fixtures and rugged internal working components of finished products.
The Elite printers have a smallish envelope build size but it doesn't limit the size of the parts we can produce. A real advantage of ABS is that it is easily and effectively joined by solvent bonding, a process of chemically melting and joining parts together that results in a solid piece when the solvent evaporates. The Fortus is an industrial model that has a larger build envelope, and it can produce parts with more types of production plastics.
It is the method we used when we built a sixteen-inch model of the Omnica sphere for the MD&M Show. We designed the three lobes of our logo as nested parts (like rose petals), and built them concurrently. We solvent-bonded them together, sanded, and then painted the completed sphere afterwards. It looks like it was constructed as a single unit. The Stratasys representative at the show was so impressed; he photographed it for his colleagues.
The auto industry uses larger versions of the machines to in-expensively build holding fixtures and templates. As another useful application, businesses can sometimes avoid the heavy cost of injection molding by using FDM and ABS plastic to produce low volume articles.
The other Objet PolyJet™ printers, an EDEN 500V and an Alaris 30, have nearly ten times finer resolution than the Dimension printers. Rather than using an extruded filament to build models, the PolyJet (Polymer-Jet 3D Printing) builds thin layers with liquid polymer which are UV-cured after each pass of the applicator head. The fine layer thicknesses result in parts that are easy to smooth and finish. They can build with special high durometer (hard) materials, and others which are typically used to simulate silicone and rubber. The Objet printing process can produce parts with walls less than 1/32" thick, a critical benefit that for us is especially important. In the medical device field many handheld products require finely featured thin wall sections.
We upgraded our additive rapid prototyping capabilities with an Objet Eden500V 3D printer. It replaces our older Eden330. This is a high resolution machine (0.0006" layer thickness) that creates models with minimal stair-steps on sloped surfaces, and it has a larger build envelope than our other five 3D rapid prototyping machines.
According to Mike Ammerman, our modelshop manager (at left), there are two other features that make this a great addition for our clients. The printer is capable of a quick-build mode that can cut time and materials costs, and unlike the other printers, this one can run unattended for 72 hours, eliminating botched restarts for large jobs. He adds by saying this machine is the best we've had for producing silicone mold patterns. Mike cast over 3000 parts last year, so he has a good idea what he's talking about.
All of our 3D printers use non-toxic and "office-friendly" processes.
Additive material rapid prototyping machines build models with integral supporting structures that are later discarded after the process has completed. Without the integral structures there would be no other way to maintain accuracy, create undercuts, or allow for moving components in a finished part. Unlike traditional stereolithography, the support structures of Omnica's printed parts are not considered to be toxic waste. They are readily disposable without restriction.
Our clients won't need a vivid imagination now that we can show them a picture in the morning, and a model later that afternoon.