Stratasys, Inc. (Minneapolis, MN; www.stratasys.com) is the exclusive
North American distributor of the "CAD to Metal" process from Arcam AB
(Molndal, Sweden; www. arcam.com). This process uses electron-beam
melting (EBM) to transform titanium alloy (Ti6Al4V and Ti6Al4V ELI) or
cobalt chromium (ASTM F75) powder into real metal parts. Although
medical implants (using cobalt chromium powder) is a big application
area, the auto industry uses EBM, as well. Parts up to about 8 x 8 x 8
in. are built by layering metal powder. A 4-kW electron beam operating
in a vacuum chamber melts the layer of powder along a contour defined
by a solids modeler. Upon completion, the net-shape part is cleaned.
(Its "semi-rough" finish can be polished as needed using conventional
machining methods.) Larger metal parts can be created by e-beam welding
parts together. EBM operates like a picture tube, explains Kirby Quirk,
senior sales executive, direct metals manufacturing, for Stratasys.
Basically magnets steer and accelerate electrons through a little
aperture. "There are no moving parts. No mirrors, servos, nothing to
get out of whack or out of adjustment. You don't have to worry about
dust on the mirrors. It makes no noise. It just runs."
Another advantage of this system is that the e-beam source does not
waver from the time it's installed till the time it burns out. This is
unlike the lasers used in conventional RP and direct manufacturing
systems. "Lasers are like people," explains Quirk. "Once they are born,
they get weaker and slower as they get older." Moreover, replacing the
e-beam element costs a fraction of what it costs to replace the laser
in conventional systems. Plus, like a light bulb, replacing the e-beam
source is a cinch. (The life expectancy of the e-beam source is not yet
known.) Because metal parts are produced directly, the lead and prep
times for casting and traditional machining are greatly reduced, in
some cases eliminated. The functional prototypes, being that they're
made out of metal, can withstand actual operating conditions, including
mechanical loads and temperatures.
[ILLUSTRATION OMITTED]
Stratasys now offers the FDM Vantage X, which starts at $99,000.
There are two configurations. The "A" configuration uses ABS, ABSi, and
PC-ABS materials; the "P" configuration, PC, PC-ISO (a medical modeling
material), and PC-ABS. Model resolution is 0.005 in. for ABS, ABSi, and
PC-ABS materials.
Stratasys has beefed up its Eden line of PolyJet RP systems, which
are manufactured by Israel-based Objet Geometries. These office systems
use a printhead that passes from left to right to deposit a layer of
photopolymer. The modeling material is fully cured with UV light during
the build process. There are now six Eden systems, ranging from the
Eden250, which has a 10.1 x 9.8 x 8-in. build envelope, to the Eden500,
which has a 19.7 x 15.7 x 7.9-in. build envelope. The trend, explains
Fred Fischer, Stratasys product manager for the Eden Distribution Line,
is that "the jetting of resins is replacing the old way of making
high-resolution parts, which is the vat-and-laser technology." He cites
cleanliness (better) cost (lower) and speed (generally faster) as
reasons. What's more, he says, "It's simpler."
By Lawrence S. Gould, Contributing Editor
RELATED ARTICLE: DUCATI SPEEDS DEVELOPMENT
During the development of a new engine for a road bike based on its
Desmosedici race bike, Ducati Motor Holding S.p.A. (Bologna, Italy;
www.ducati.com) first built the engine out of polycarbonate. Not quite
the same as the real thing, but close enough to validate the new engine
design. In working to develop the engine, Ducati used Stratasys FDM
(Fused deposition modeling) systems. According to Piero Giusti, R &
D CAD Manager for Ducati Motor Holding, Ducati has assembled and
analyzed an entire engine without machining a single metal piece.
In designing the new engine based on its Desmosedici MotoGP race
bike, Ducati used Unigraphics NX2 CAD/CAE software
(www.ugs.com/products/nx/). The engine layout--a twin-cylinder,
oval-piston configuration--was designed to have the power and torque of
a conventional twin-cylinder engine, plus the necessary performance to
compete against multicylinder engines. Ducati then produced an engine
model assembled with polycarbonate components built within the 16 x 14
x 16 in. build envelope of its in-house Stratasys FDM Titan system.
Then the design strategy changed. A new engine was designed with an
L-shaped layout and four round pistons using a two-by-two firing order,
which reproduced the working cycle of a twin-cylinder engine. Again,
the engineers built a new prototype out of polycarbonate.
In the past, Ducati employed RP service bureaus to make such
prototypes. In designing and building a previous engine, that approach
took 28 months. With FDM in-house, designing and assembling the
Desmosedici engine took only 8 months. "Prior to purchasing the FDM RP
systems, our service-bureau expenses totaled approximately 1 million
euro per year. That was much higher than the cost of purchase,
maintenance, and materials For our two FDM machines," says Giusti.
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