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December 12, 2000

8 Min Read
Market Focus: Sports and Recreation


Less ismore," says Tobie Hatfield, senior advanced product engineerfor athletic equipment and sportswear giant Nike Inc. (Beaverton,OR). For track and field footwear, which is Hatfield's area ofexpertise, this means that advances in materials technology arebringing athletes closer to the turf with thinner sole plate profiles,yet are generating stiffer products. And although the sports andrecreation market is just a small bite of the overall injectionmolding market pie, this industry segment's

technology played a significant role in the most widely recognizedsporting event in the world last September in Sydney, Australia.Olympic gold medalists Michael Johnson and Marion Jones both worespecially developed Nike running shoes with sole plates that reachednew levels in light weight and stiffness.


For Nike, these successes are the result of teaming with materialsuppliers and molders, says Hatfield. The company operates a captivemolding facility, but contracts with other molders when specialtymachines and processes are required. Rather than Nike always approachingmolders with its own ideas, Hatfield suggests that he'd like tosee more molders come to the athletic firm with new, innovativeprocessing methods, or even those borrowed from other industries."We're not looking for gimmicks," he contends. "Itdefinitely has to help the athlete."

For example, Hatfield spoke with a metal injection molder afew months ago to explore molding metal spikes, instead of coldforging them. He says Nike is also looking into a completely metal-freespike plate, which has advantages in assembly and recycling. Whileneither of these ideas has been implemented yet, Hatfield recognizesthat input from the molding community can play a significant rolein bringing about advances in footwear.


Other trends show an increased popularity in sportsthat some may classify as higher-risk than track and field (seetable, top), and Roger Ball, director of Paradox Design in Toronto,ON, has witnessed this first-hand. "People are getting accessto more extreme environments outdoors a lot easier than they everhave before," he notes. This departure from team sports opensa whole new category of parts for molders, which, significantly,includes protective gear. Ball sees this most prominently in watersports such as wakeboarding, jet skiing, and kayaking, where itemslike eyeglasses, helmets, and flotation vests are necessary whensoft water becomes painful at high speeds.


Gasassist gives a lift
to golf cart roof


Everyoneknows that taking out weight while maintaining strength is a goalfor converting to plastic in cars. But what about when the caris for more recreational purposes-say, golf? The same goal applies,says Club Car of Augusta, GA, a golf cart manufacturer.

In considering the design for its Millennium model, it replacedits tubular steel armrests with gas-injection molded parts, moldedby Thomson Plastics Inc. (Thomson, GA) under license from Cinpres.When it was clear that gas assist provided the right combinationof surface quality, strength, and light weight, Club Car decidedto apply this processing method to the roof.

Previously, the cart's canopy had been vacuum formed. The redesignfor the 2520-sq-in roof-one of the largest ever produced by gasassist, according to Cinpres-aimed to improve aesthetics, easeof installation, and durability. The latter is vital since thecanopy must provide structural support. Don Samuelson, chief designerfor Club Car, says the process involved marrying many elementssuccessfully. "We had a number of detail requirements tomeet," he explains, "including incorporating water channels,hand holds, punched holes for the steel roof supports, and provisionfor windshields and other accessories." Secondary operationsalso needed to be eliminated.

Following the initial evaluation, design and production engineerscollaborated with moldmaker Model Die & Mold Inc. (Grand Rapids,MI) to create a tool with a single hot bushing and two Cinpres10-mm gas nozzles. The engineers used Moldflow software to optimizethe feed point and nozzle locations.

An 18.4-lb shot of a custom 20 percent calcium carbonate PPcopolymer grade from Basell Polyolefins (formerly Montell) fillsthe mold-less material used than in the vacuum forming process.Final tests revealed smooth radiuses, no sink marks or lines,and strength to withstand repeated blows with a two-iron.

In addition, since the canopy's features are molded in, secondaryoperations have been eliminated. The molder is also able to usea 2200-ton Milacron press for this process instead of the 6000-tonmodel originally considered. The cycle is fully automated andrequires one operator.

Cinpres Ltd.
Ann Arbor, MI
Phone: (734) 663-7700
Fax: (734) 663-7615
Web: www.cinpres.com

Basell USA Inc.
Wilmington, DE
Phone: (302) 996-6322
Fax: (302) 996-6380
Web: www.basell.com


Nylonlightens, stiffens runner's shoe


WhenMichael Johnson flew around the track in Sydney, winning the 400mgold medal, he was wearing Nike track spikes with a 30g, custom-engineeredsole plate made just for him. The sole plate weighs less thanhalf that of standard racing soles and is about 40 percent stifferthan the one Johnson previously used. Made of 13 percent glass-reinforcedsuper-tough Zytel nylon from DuPont, the soles withstood morethan 10,000 flex cycles during Nike's quality testing.

"We did a lot of research here at Nike, testing severalmaterials and combinations of materials," says Tobie Hatfield,senior advanced product engineer at Nike Inc., "and we foundthat Zytel nylon allowed us to stiffen the sole without increasingweight." Nike, located in Beaverton, OR, molds the partsin-house.

DuPont Engineering Polymers
Wilmington, DE
Phone: (800) 441-0575
Web: www.dupont.com/enggpolymers


TPEgives swim fins strength, snap


Diverscan now swim farther with less effort, thanks to a new designin swim fins. The Twin Jet fin from Scubapro (El Cajon, CA), amanufacturer of diving gear and equipment, incorporates a dual-bladedesign that converts a greater amount of the diver's kicking energyinto forward motion than other swim fins, according to SergioAngelini, director of engineering for Scubapro.

"With a conventional paddle-shaped fin, each kick createsturbulence that wastes energy," he explains. "Waterdisplaced by the Twin Jet fin, however, is redirected over thetop and bottom of each blade, creating a pressure differentiallike that which generates lift in an aircraft wing." Also,vents were designed into the fin to allow water to flow throughafter passing over the blades.

To enable the fin to snap back quickly after each stroke andresist tearing, Scubapro needed a tough material with good elasticmemory. After evaluating thermoset rubber, the company chose MonpreneTPE from QST Inc., part of Teknor Apex.

James McGee, president of Pacific Molding Inc. (Corona, CA),which molds the fins, says natural rubber formulations did notprovide adequate weatherability, while highly weather-resistantEPDM synthetic rubber did not give the right snap. Monprene satisfiedboth requirements in addition to providing low coefficient offriction for minimal drag in water.

Pacific Molding encountered problems in the thick rib alongthe outer side of the fin. McGee explains, "We needed tofind a way to cool a part that thick without refrigerated water,which would have compromised its surface appearance." Partof the solution came when QST modified the compound to optimizeprocessing.

Teknor Apex Co.
Pawtucket, RI
Phone: (401) 725-8000
Fax: (401) 729-0166
Web: www.teknorapex.com


Quick-releasebinding lock finds strength in nylon


Analternative design in snowboard bindings enables riders to attachto and detach from snowboards using just one hand. BelligerentSnowboard Bindings (Pacific Beach, CA) converted to this designfrom the typical binding strap paradigm, which requires two hands.The new Sinch Strap binding lock is an accessory bolted to theside of the binding that is operated by pushing or pulling onit for securing or releasing the binding.

Two elements were critical when selecting the material forthe binding lock: strength, especially at very low temperatures,and good surface appearance. Belligerent tried a standard glass-fillednylon, but found the strength inadequate. Ultimately, the manufacturerchose Verton FR long-glass-fiber-reinforced nylon 6/6 compositefrom LNP for its stiffness, Izod impact strength (4 ft-lb/in at-40C), and surface finish.

"We chose the Verton RF composite because of the longglass fibers," says Scott Bumgarner, vp and head of R&Dat Belligerent. "The fibers set up the form and the infrastructureinside the lock's components and make them more rigid." Healso comments on the fibers' ability to provide a clear, clean,colored finish. "With the previous material, the glass fiberswere essentially like sawdust-they all came to the surface andleft blemishes."

Other components in the binding also molded with Verton RFby TNT Molding (Anaheim, CA) are a bar to which the binding strapsare attached, and a pivot point under the front that locks inback with a buckle. The buckle is a combination of the nylon compositeand a metal stamping.

LNP Engineering Plastics Inc.
Exton, PA
Phone: (610) 363-4500
Fax: (610) 363-4749
Web: www.lnp.com


Ballsmay fly farther with TPE tee


>Golfers, it's said, will do anything to gain an edge in the game, and anew tee from molder GDI Plastics (Heathfield, U.K.) promises toprovide this advantage by increasing shots off the tee by an additional9 yd. The tee, called Jellyhead, consists of a soft thermoplasticelastomer top and a hard polyamide for the lower portion. Bothmaterials have to withstand the golf club's impact. For the head,a modified Bergaflex TPE from PolyOne (formerly M.A. Hanna) wasselected; the supplier's impact-modified super-tough Bergamidpolyamide was the choice for the lower point. Because of the materials'modification, the proper adhesion was achieved between the polarpolyamide and the nonpolar TPE during overmolding.

PolyOne Corp.
Cleveland, OH
Phone: (216) 589-4000
Fax: (216) 589-4200
Web: www.polyone.com


Acrylicused as alternative to PC in moped light


Thefront headlight of Aprilia's (Noale, Italy) Scarabeo moped isbeing molded with an acrylic resin instead of polycarbonate, thestandard material for this application. Oroglas HT 121, developedby Atofina's subsidiary Atoglas, was chosen for its easy processing,strength at high temperatures (up to 121C), good light transmissionproperties (90 percent), and resistance to UV radiation, weathering,and scratches. No postmolding surface treatment is required withOroglas, say Atofina sources. Dharma Plast (Peschiera Borromeo,Italy) molds the headlight.

Paris, France
Phone: +33 (1) 49 00 89 74
Fax: +33 (1) 49 00 89 59
Web: www.atofina.com

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