Machine Design

Bull's-eye for carbon-reinforced polyamide

The game of darts has become more than a bar sport, complete with touring professionals.

To this end, German dart supplier Evolution Dart-Technologie used carbon fiber-reinforced polyamide (PA66) to improve reliability and prolong the performance life of its products.

There are four components in a dart. The most apparent to non-players are the tip, the barrel (gripped by the player), and the flight (fins that stabilize the dart as it moves through the air). The fourth component is the small but critical shaft, which connects the barrel and the flight. The shaft is threaded at one end and screws into the barrel. The flight affixes to the shaft by rings or other fasteners. Different lengths are available to vary dart performance. The shaft can be made of metal, plastic, or a combination of plastic and a threaded metal segment.

Evolution injection molds its 34 and 44 mm (1.3 and 1.7 in.) shafts from Beetle 66CF4, a 20% carbon fiber-filled PA66, from Chem Polymer, Ft. Myers, Fla. "The high stiffness gleaned from the PA66 let Evolution replace metal in the shaft, saving weight," says Inge Wrtz, Chem Polymer sales manager. "The compound's dimensional stability provides an accurate and secure connection between the flight and the barrel. And the carbon fibers provide greater flexibility than comparable glass-fiber-filled composites, which are more brittle."

"The perpendicular forces generated in the dart as it strikes the target are great enough to pose a real challenge for other all-plastic shafts," says Roland Kühn, owner of Evolution, "but the tensile and flexural properties of the Beetle compound let our shafts better withstand considerable stresses from repeated use by intensely competitive dart players."

More Information:
Evolution Dart-Technologie
Chem Polymer,
a business of Teknor Apex Co.

Darts sporting carbon fiber-reinforced polyamide shafts are lighter than those with metal counterparts and exhibit greater resistance to breakage than conventional thermoplastic shafts.

The 34 and 44 mm shafts are injection molded from Beetle 66CF4, a 20% carbon fiber-filled PA66.

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