Superstrong nuts and bolts

Sept. 18, 2003
Formula 1 race teams constantly push the mechanical limits of fasteners that attach chassis and aerodynamic components to their race cars. Swiss-based fastener maker, Icotec Ag (www.icotec.ch), produces fasteners that meet the challenge.

Using composite flow molding (CFM) and a polyaryletherketone resin reinforced with long-carbon fibers, Icotec's lightweight nuts and bolts sport ultrahigh specific strengths of up to 2.4 million psi/lb/in.3 This contrasts to aluminum and titanium with specific strengths of about 0.2 million and 1.2 million psi/lb/ in.3, respectively. The composite's semicrystalline polymer matrix called PEEK, from Victrex USA Inc., Greenville, S.C. (victrex.com), also has a melting point of 649°F, a glass-transition temperature of 289°F, and a continuous-use temperature of 500°F.

According to Chris Karas, spokesperson for the resin supplier, "CFM feeds the pultruded composite rods into a closed preheating cavity. From there, the rods move to the mold and are formed to shape under pressure with helically reinforced threads which are protected against abrasion by the fastener tapping the bore." The high-volume CFM process produces fasteners in a single step without the need for any posttreatment.

Even with high fiber loadings, fastener threads can sustain high mechanical loads without shearing, thanks to a transitional fiber-orientation zone that transfers forces away from the threads to the fastener core. In contrast, conventional thermoplastic processing techniques don't permit extremely high fiber content nor can they process long fibers without damaging them. Consequently, fasteners subjected to high mechanical loads, as seen in Formula 1 race cars, are typically machined from a blank.

In addition to the motor-sport application, CFM nuts used in marine applications reportedly resist pounding vibrations without loosening. Various aerospace agencies are also evaluating CFM fasteners to further reduce weight in assemblies and to better match fastener thermal expansion coefficients to those of the composite they assemble.

Fasteners made from carbon-fiber filled Victrex PEEK also sport flexural strengths ranging from 116 to 145 kpsi (800 to 1,000 MPa) and tensile strengths up to 65 kpsi (450 MPa) depending on fiber type and loadings.

Sponsored Recommendations

Pumps Push the Boundaries of Low Temperature Technology

June 14, 2024
As an integral part of cryotechnology, KNF pumps facilitate scientific advances in cryostats, allowing them to push temperature boundaries and approach absolute zero.

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.

MONITORING RELAYS — TYPES AND APPLICATIONS

May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!