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Ryobi
 Trendsetter
Ryobi sought to create the ultimate 'CleanAir'
engine to power its popular line of grass and weed trimmers. Using stereolithography
as their cutting edge, Ryobi's new Pro4Mor engine emerged lighter, less costly,
and in perfect harmony with the environment.
The Challenge
Ryobi faced a cascade of challenges last year to launch its new four-cycle
Pro4Mor
trimmer engine. First, the 1995 and 1999 California Air Resources Board (CARB)
standards for
lower emissions in gaspowered utility products were around the corner. Two-cycle
engines are standard, but
Ryobi wanted to develop an entirely new four-cycle solution that would meet 1999
standards. Second, the new engine had to be smaller and lighter, to please their
customers' appetite for
convenience. Third, from design and manufacturing to the store shelf, costs had
to be controlled.
To complicate the challenge, Ryobi needed final parts ready in time to exhibit
functional prototypes at the International Lawn and Garden Expo, only four months
away. Ryobi needed functional
prototypes to perfectly mimic the ultimate final product, including finished
materials,
requiring injection molded production prototypes.
Ryobi turned to a contact at AlliedSignal's Engineered Plastics Group who, in
turn, brought in Laser Prototypes (LPI), a veteran stereolithography (SL) service
bureau in Denville,
NJ. LPI proposed injection molded parts made from epoxy molds using SL patterns.
With the challenge firmly
in hand, the trio of experts set out to make history.
The Results
Pro4Mor debuted to critical acclaim, marking an "environmental and technological
breakthrough for the entire outdoor power equipment industry." Customers
and servicing dealers
approached the Ryobi booth in amazement -- they had never before used a functional
four-cycle engine
so small and light. Dubbed the CleanAir engine, the Pro4Mor uses 30 percent less
fuel. It's been
awarded Popular Science Magazine's "Grand Award" for design of the
year and now powers Ryobi's
String Trimmers and Brush Cutters. Better yet, sales have surpassed all projections,
prompting Ryobi to
increase its 1994 production schedule. What Ryobi discovered about versatility
of SL will last long after
the awards:
- Detect design
flaws early
- Produce
epoxy generated tools in record time from SL patterns
- Use SL patterns
for investment casting of aluminum components
- Address
seven different tooling techniques
- Produce
functional prototypes in end use materials like Capron
- Use SL parts
in controlled customer settings for product testing
- Save four
months in production at 30 percent lower cost over conventional methods
"From a design and development standpoint, stereolithography
is a key factor to accomplish concurrent engineering project schedules
in
a competitive time frame."
- Ryobi Outdoor Products
The Process
To produce six prototypes in production material in a matter of weeks
was a daunting challenge. Fortunately, development had been progressing
on the crankcase and engine cylinder for some months, so the Ryobi team
was not starting from ground zero. Ryobi's in-house design engineers
created their initial concepts in Pro/ENGINEER and quickly and conveniently
made design changes exchanging their .STL files back and forth with LPI.
Since every part was to result in a production mold of some type,
the parts had to provide an enormous amount of detail.
Twenty-three different parts were built, including upper and lower
handles with trapped volumes placed together; a hollow fuel tank; a large
thin-walled engine cover; an air filter cover with labels and symbols
and the functional threads on an oil plug. Multiple iterations produced
15 sets of parts out of each prototype tool. In fact, SL parts were used
for a variety of tooling techniques:
- Epoxy molds
for injection molded pieces
- Silicon
rubber molds for waxes to investment cast
- Silicon
rubber RIM molds for functional urethanes
- Spray metal
molds for production material parts
- Rotational
and production blow molds for the fuel tank
- Investment
casting for the small eyelet and tool cores
Typically,
the procedure went from .STL file to SL part in a rapid 2 to 3 days. Then,
once design changes were agreed
on and scale factors incorporated, it took only 3 to 4 weeks
for Laser Prototypes to produce the epoxy tool or prototype mold/tool
for injection molding of the plastic pieces.
One side note: according to Laser Prototypes, the SL functional
prototypes were so precise that Ryobi was able to test
the epoxy-generated prototype trimmers as running models, complete
with oil and gas pulsing through the engine.
Company Profile
North American headquarters of Ryobi Limited, a $2 billion
diversified corporation, are located in South Carolina.
Ryobi manufactures a wide range of industrial and consumer products
with international presence in Asia, Europe, Australia,
and North America. Major U.S. divisions include Ryobi Motor Products,
Ryobi Die Casting, and Ryobi Outdoor Products, the latter
based in Phoenix, Arizona, USA. The company is known for its quality-driven
culture and commitment to leading-edge technology, as evidenced by the
popularity of its products with business, industry, and consumers.
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