Rapid Prototyping: From Art To Part

Rapid Injection Molding Gets Big

With the ability to turn CAD models into real molded parts in as little as a day, Protomold’s rapid injection molding service is undeniably fast. Still, the service has never been a cure-all for the long lead time blues because Protomold’s automated tooling and molding systems impose size and geometry limitations that rule out some plastic part designs. Earlier today at the Pacific Design & Manufacturing Show in Anaheim, the company literally had some big news about those limitations. According to senior quality engineer Kevin Crystal, Protomold’s rapid injection molding system now accommodates parts with projected areas up to 175 in², up from  75 in² in the past. Maximum x-y dimensions have increased to 13.5 x 30.5 inches, subject to that projected area limit. Maximum depth for the large parts is now 3 inches from either side of the parting line, or 6-inches total for parts that can be divided equally between mold halves. Part volume now tops out at 59 in³. Protomold will run the large parts on a newly-acquired 750-ton molding machine. Lead time for the big parts will initially be 15 days.

3D System's New Desktop Modeler

Though best known for its high-end prototyping machines, 3D Systems has now created a new low-cost desktop modeler aimed at design engineers who want to build their own prototypes. And thanks to the machine’s compact size and low cost, those engineers may soon be able to build those models without even leaving their cubicles.

This new V-Flash modeler, which comes in versions for general purpose use and for hearing aid production, sells for just $9,900, a fraction of what the company’s stereolithography (SLA) machines cost. As for its desktop status, the new modeler measures 26 x 27 x 31 inches and weighs about 145 pounds.

V-Flash makes use of an entirely new technology platform that 3D Systems calls Film Transfer Imaging. For each cross-sectional layer of the model, the V-Flash sends out the build material on a retractable transparent film that extends from the machine’s disposable material cartridge. "It works something like a window shade," says Buddy Byrum, director of global marketing for 3D modeling products.

Working with the model upside down on a single-use build pad, the machine then selectively light cures the build material from below the film. The V-Flash repeats that process, building the part layer by layer with each cure cycle corresponding a particular part cross section. Uncured material rides back into the cartridge atop the film. Maximum build size is 9 x 6.75 x 8 inches, in the x, y and z directions, respectively.

According to Byrum, the machine has a resolution of +/-0.009 inches, which is the minimum pixel size of the system’s optics. The V-Flash can locate features within 0.002 to 0.005 inches and build vertical walls down to 0.25 inches. Build speed is currently about 0.5 inches/hour in the z-direction.

To keep the cost of the system low, 3D Systems put most of the machine’s complexity, and many of its wear components, within the disposable material cartridge. This 1.8 kg cartridge costs about $850 and contains 104 cubic inches of material. Do the math and that sounds like some pretty expensive modeling, but Byrum notes that the FTI process inherently has very high material utilization rates and requires relatively few material-intensive support structures. "Almost all the material becomes part of the part," he says. "The bottom line is that the cost per cubic inch is comparable to other technologies." He estimates that the cost of finished parts usually ranges from roughly $8.50 to $9.00 per cubic inch, depending on part geometry, orientation and other build factors.

Anyway, for true desktop modeling in design environments the convenience factor will likely outweigh any penny-pinching over model costs. "The idea is to put a modeler in every design engineer’s hands," says Byrum.

And 3D Systems isn’t alone in its push to make modeling more accessible with a low-cost, compact additive system. Another type of low-cost additive fabrication system from Desktop Factory debuted last year with an even lower price tag than the V-Flash. Read about it here. EnvisionTec, which has traded some legal barbs with 3D Systems over the technology used in the V-Flash, is also marketing a low-cost modeler. Read about it here.

Stratasys’ Latest Direct Digital Manufacturing Move

Suppliers of additive fabrication systems have been touting the potential for direct digital manufacturing for years. Now more of them are starting to walk that walk–by using their own additive machines to make parts for their new machines. The latest example comes from Stratasys, which this week revealed that 32 of the parts on its latest large-format fused deposition modeling (FDM) system were produced via FDM.  This machine, the FDM 900mc, features a big 3×2x3-ft build envelope and has been designed from the ground up to support direct digital manufacturing. Among the FDM parts on the new machine is a touch-screen bezel. With direct digital manufacturing, Stratasys can create this low-volume part on demand, saving an estimated $100,000 of tooling costs and at least six weeks of tooling lead time.  Stratasys isn’t alone in using its own technology to procure parts for its machines. EOS GmbH has employed a similar strategy on its Formiga P100 system. Read about it in this earlier post.  For a more comprehensive look at direct digital manufacturing news and some how-to tips, go to Design News’ Factory of the Future page.