Overnight Golf Shoe Soles Beat Par

Rapid prototyping and innovative plastics speed development cycle

The golfing community is aiming for holes in one, not holes in the green, because many golf courses now discourage -- even ban -- the use of traditional metal-spiked footwear. Despite the new green-saving rules, proper traction remains pivotal to a winning golf swing, a crucial factor as athletic shoe manufacturer Reebok began development on a spikeless golf shoe sole design. Although this promising idea was still in its early development stages, Reebok realized that the new sole design would need to be properly tested. This required creating prototype soles, then attaching them to an actual pair of shoes that would be worn on a course by an experienced golfer.

These Reebok prototype spikeless golf shoe soles, developed using a DTM Sinterstation, are as they appeared following a traction test of two trial rounds played by an experienced golfer

Following a traditional prototyping course of standard tooling and injection molding costs Reebok $3,500 to $4,000 with a turnaround time of 30 to 60 days. This time, the company's in-house rapid prototyping lab offered another solution to reduce prototype development time and costs. The lab's equipment included a DTM Sinterstation 2500 system from DTM Corporation, Austin, TX, which provides a variety of prototyping operations and also offers a range of material options from which to choose.

One of these materials was DSM Somos 201, an elastomeric polymer that produces flexible parts with rubber-like characteristics, manufactured by DSM Somos, New Castle, DE. Since 1997, Sinterstation users have used Somos 201 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 designed in 3-D CAD, then the file was translated into the STL format required by the Sinterstation system. Next, Reebok generated both a left and a right golf shoe sole prototype in Somos 201 on the system. Build time was just seven hours.

"With Somos 201, typically the first build is the right build, and it takes only a few hours," said Paul Bates, rapid prototyping lab manager for Reebok Unlimited's advanced process engineering group in 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, thanks to the flexibility of the material being used. No special methods were needed, only standard assembly processes and materials.

Putting it to the test

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. The golfer was instructed to put the shoes on as close to the course as possible (to avoid premature wear on concrete or other man-made surfaces), 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, then turned the shoes back into Bates and offered an honest review.

Reebok prototype spikeless golf shoes

"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," reported Bates. "I was thrilled. The test was a success because the Somos 201 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 continued, "The 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."

As predicted, performing the test with Somos 201 soles saved the company $3,500 in tooling costs and at least 30 days of development time. "Making the soles was an overnight build on our Sinterstation with about $250 worth of material," Bates said. "Using this method allows us to compress our modification stage down to almost nothing." Bates added that projects like this often require multiple iterations and several rounds of testing before an idea is perfected, compounding development expenses and delaying project completion when using the traditional method of tooling and injection molding. Bates stated that the use of Somos 201 and the rapid prototyping method has made a tremendous impact on development cycles at Reebok.

--FR

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