Another Solution for Dramatically Reducing Prototype Development Time and Costs

With competition becoming fierce in golf shoe design, companies must develop, test and produce new designs with both aesthetic appeal and high performance - and they must do it faster than their competitors. Using a Sinterstation® and an elastomeric polymer, Reebok® produced a new design overnight - saving $3,500 in tooling costs and 30 days of lost time.

Recently, Reebok®'s Golf Division began work on a new spikeless golf shoe sole design - one it hoped to add to its currently successful line of spike and spikeless products. This project was of certain interest to company marketers because many golf courses now discourage - even ban - the use of traditional metal-spiked footwear. But, despite the new green-saving rules, good traction remains pivotal to a good golf swing.

Although this promising new idea was still in its early development stages, Reebok® knew the new sole design would have to be properly tested. This required creating prototype soles, then attaching them to an actual pair of shoes - and an experienced golfer.

Following the traditional prototyping course (standard tooling and injection molding) currently costs Reebok® $3,500 to $4,000 with a turnaround time of 30 to 60 days. In contrast, the company's in-house rapid prototyping lab offered another solution that would dramatically reduce prototype development time and costs. The lab equipment included a Sinterstation®¹, which provides a variety of prototyping applications and also offers a range of material options from which to choose.

One of these materials was an elastomeric polymer² that produces flexible parts with rubber-like characteristics - this material has been used to create parts such as gaskets, seals and moldings. For Reebok®, it proved to be an excellent choice for prototyping spikeless golf shoe soles.

To prepare the new design for prototyping, the sole was prepared in 3-D CAD then the file was translated into the stereolithography format required by the Sinterstation® system. Next, Reebok® generated both a left and a right golf shoe sole prototype in elastomeric polymer on the Sinterstation®. Build time was only seven hours.

"With this elastomeric polymer, typically the first build is the right build, and it takes only a few hours," says Paul Bates, rapid prototyping lab manager for Reebok® Unlimited's Advanced Process Engineering Group (Randolph, MA). "It builds quickly, and once you learn how to use it, it's pretty easy to handle. Then it's just a matter of finishing it and bonding it onto the shoe. You can conceivably do all that in less than 24 hours."

Finally, the prototype soles were attached to a pair of existing golf shoes, a process that Reebok® prototypers found remarkably easy and routine, thanks to the flexibility of the elastomeric polymer material. "We didn't have to invent any special processes or come up with some high-tech, two-part, epoxy bonding method with a 48-hour cure," Bates emphasizes. "We just used our standard assembly process and materials. It was really convenient."

The shoes were then turned over to a tester who was advised by Reebok® that this was neither a durability test nor an abrasion test; it was simply a traction test. "He wasn't supposed to go run around the parking lot in the shoes and then wonder why the bottoms wore off," Bates adds. "We told him to put the shoes on as close to the course as possible, then go hit some balls, play a few rounds, walk up and down some slopes, step through some mud and put the sole design through the paces of an active golf game." The tester completed one trial, requested a second, turned the shoes back in to Bates and his colleagues and offered an honest review.

"He basically said the design wasn't what he had expected and pointed specifically to an area on the sole that appeared to be a trouble spot," reports Bates. "I was elated. I was thrilled. The test was a success because the elastomeric polymer soles did exactly what they were supposed to do -they didn't fall off the shoes, they didn't delaminate or wear down and the lugs didn't break off as the tester walked around in them."

Bates continues, "The elastomeric polymer soles did everything they had to do for testing purposes. They were functional, and they lasted long enough to prove that the design and the traction were not right."

Benefits to Reebok®

Bates adds that projects like this often require multiple iterations and several rounds of testing before an idea is perfected. "Just think," he says, "if we can save this kind of money and this much time with each iteration - well, you can see how it can add up.

"Our competitors are coming up with new designs all the time," explains Bates, "and with golf becoming more popular, especially with younger people, it's important that we develop, test and produce new designs with both aesthetic appeal and high performance. We also have to get our products into the stores sooner. To do that we need to push new designs through the process faster. Using the Sinterstation® and materials like elastomeric polymer, we can make that happen."

Bates concludes, "Elastomeric polymer is really the only material of its kind out there that we could have used with our Sinterstation® for this kind of application. The combination of this material and the SLS process has made a tremendous impact on our work here at Reebok®."

¹DTM Sinterstation® 2500 system.

²DSM Somos® 201.

Somos is a registered trademark of DSM Desotech.