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.

"From a design and development standpoint, stereolithography is a key factor to accomplish a concurrent engineering project schedule in a competitive time frame."

- Ryobi Outdoor Products

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 gas-powered 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 Allied-Signal'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 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 SLA parts in controlled customer settings for product testing
• Save four months in production at 30 percent less cost over conventional methods

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 LPT. 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

The Tools

• Pro/ENGINEER design software
• SLA 250
• AlliedSignal Exactomer resin

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. 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.