“Urethane materials have improved dramatically in the past few years,” said Dave Crawley. “Coupled with the right procedures, Stratasys Direct Manufacturing is able to produce parts that are indistinguishable from injection molded production parts in a fraction of the time it would take to produce the hard tooling needed for injection molded parts. For Star Trac, that meant they were able to complete the delivery of their new Elliptical EDGE Trainer despite the unexpected delay in producing the tooling.”
Stratasys Direct Manufacturing, a leading supplier of rapid prototyping and manufacturing services, was called in to help alleviate the problem. Rapid prototyping service bureaus such as Stratasys Direct Manufacturing typically provide quick turnaround for small quantities of parts. Stratasys Direct Manufacturing has a wide range of rapid prototyping technologies available, but they recommended their QuantumCast™ Urethane Casting process to create the parts from silicone rubber tooling. According to the Stratasys Direct Manufacturing Engineering Manager for this project, Dave Cawley, “Quickly producing hundreds of urethane castings with the quality and consistency of injection molded parts requires a level of sophistication well beyond what is usually needed for one or two urethane castings.
“Of the three components needed for the Star Trac job, the grommet was the most complex and difficult to work with,” said Cawley. The grommet was an L-shaped component with a flange.Nonetheless, Cawley found that new urethane materials, special equipment, and procedures would enable Stratasys Direct Manufacturing to meet Star Trac’s requirements for performance and quality, while still getting the hundreds of Elliptical EDGE machines off the shipping floor in time.
The foot pads were the most visible components needed and aesthetics were very important. The final texture and color of each 13” x 6” footpad had to be identical so that when lined up on a fitness room floor there would be no difference between them. Repeatability and consistency of the production parts was a must.
The part quantities Star Trac needed would stretch Stratasys Direct Manufacturing’ production capabilities, but would emphasize their many years of experience working with urethanes.
Stratasys Direct Manufacturing’ QuantumCast process is a multistep process that applies vacuum, heat and pressure to process advanced formula polymers (AFP’s) that result in void-free, strong and stable pre-production or early production components. This next generation polyurethane technology and Stratasys Direct Manufacturing’ ability to fabricate their master pattern directly from Star Trac’s CAD drawings further assured that the grommets and foot pads had optimum mechanical properties. To meet production needs, ten master patterns needed to be produced. Custom finishing then topped off the process.
With a clear understanding of the design parameters and specific characteristics needed by the customer, Stratasys Direct Manufacturing was able to provide interim, production quality components to address Star Trac’s immediate production needs. According to Crawley, “Urethane materials have improved dramatically in the past few years. Coupled with the right procedures, we are able to produce parts that are indistinguishable from injection molded production parts in a fraction of the time it would take to produce the hard tooling needed for injection molded parts. For Star Trac, that meant they were able to complete the delivery of their new Elliptical EDGE Trainer despite the unexpected delay in producing the production tooling – making all of this more than an academic exercise.”
