With a surge in water activities over the past few years, specialized swim and surf products have cropped up in numerous segments of the market. By using state of the art technology, engineers are able to create a product that sets them apart in the field.
By Rosaleen Welsh, Associate EditorFor many, swimming is an activity where quickness and velocity are not part of the equation. But putting on a pair of swim fins can change everything.
Swim fins are becoming an essential piece of equipment for water sports because they promise increased speed, efficiency, and stamina. However, a stiff or loose fit – not to mention the ensuing blisters – can diminish the pleasure associated with them.
Neofin Corp. of Laguna Beach, CA, and Force Fin of Santa Barbara, CA, are two companies that re-evaluated the materials they use in their designs to produce something a little bit different. Here are their stories.
Fin-Tastic Voyage
Who knows what makes a good fin? Someone who uses them extensively, of course.
Matthew McLaughlin, a long-time surfer, body boarder, and diver, knew all the potential problems associated with swim fins. That's why he came up with an idea for a line of fins that features a materials configuration designed to improve performance. He then partnered with Neofin Corp. to turn his idea into reality.
However, when engineers at Neofin began designing the fins, they quickly discovered a problem. The material originally chosen for the sole of the swim fins wasn't living up to manufacturing requirements. Specifically, the soft EVA foam could not be successfully glued and sewn onto the stiff injection molded fin. Therefore, a new material was needed.
Neofin officials, as well as officials from KuiCo, the custom injector molder that helped manufacture the fins, approached the thermoplastic elastomers division of GLS Corp. for help on this application. Because there would be several demands placed on the new material, GLS recommended Dynaflex G7900 Series high-performance TPE compounds. In addition to being designed for processability and reduced cycle times especially in demanding, complex parts, Dynaflex compounds were able to provide both the soft and non-slip properties required by the swim fins.
Dynaflex allowed the engineers to injection mold the fins while still meeting the performance criteria laid out in McLaughlin's original design. The final fins feature calibrated side ribs that extend above and below the planar surface of the blade – the part of the fin that cuts through water to propel the swimmer. They provide enhanced water channeling while adding strength to the blade.
The result is a high-powered blade that is not subject to unwanted distortion during powerful flutter kicks. The design also prevents ankle torque and keeps the blade perpendicular so that McLaughlin and his fellow water enthusiasts stay on the move.
Optimizing Design
Just as Neofin found the right material, so too did Force Fin. During the development of Force Fin's Fab Force line of swim fins, the company's engineers considered and tested materials such as vinyl, rubber, nylon, urethane, coated nylon fabrics, and vinyl coated polyester and nylon fabrics, but none seemed to work. That's why they turned to Stevens Urethane, a manufacturer of thermoplastic urethanes or TPUs.
The Force Fin engineers cut sheets of TPU film in a pattern for the fins in order to sew them together. Then they placed a castable polyurethane between the TPU sheets. The castable polyurethane bonded with the Stevens Urethane TPU and hardened, giving the fin its structural form.
The TPU film serves as both the mold and the outer skin of the finished product. It bonds with the internal polymer, matches its elasticity, and provides a durable, high-gloss outer layer. For Force Fin, the elasticity, durability, and abrasion resistance of the materials were crucial to product performance.
The TPU used to manufacture the Fab Force fins not only satisfied those concerns but also helped improve the speed, or snap, of the fins, which can increase their propulsive qualities. In addition, it helps prevent the fins from delaminating, even with repeated flexing from kicking up and down. Also, the TPU's high abrasion resistance does not pierce or tear when it comes in contact with sand, rocks, barnacles, or other abrasive surfaces typically found in underwater environments.
Moreover, the TPU enabled Bob Evans, a designer and Force Fin's president, to develop a manufacturing technique that eliminates the need for expensive molds for prototyping and production. The new process allows the fins to be quickly prototyped and tested. As a result, the engineers were able to design, test, and tweak the fins throughout the development process at a fast pace and with low costs.
With these new processes streamlined, dealing with underwater adventures is more fun, and easier, than ever.
Stevens Urethane9 Sullivan Rd.Holyoke, MA 01040(413) 533-8100 GLS Corp.833 Ridgeview Dr.McHenry, IL 60050(815) 385-8500
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