Valuable Fasteners

Mechanical fasteners inspire mixed feelings among engineers. On the one hand, nuts, bolts, screws and their ilk are a necessary part of many assemblies. On the other, smart engineers apply all their design powers to keep the number of fasteners to a bare minimum — avoiding weight, assembly time, potential failures and, ultimately, cost.

Fastening suppliers are acutely aware that engineers need fasteners but often use them grudgingly. Some suppliers respond by making important yet incremental improvements to fastening products — think new thread forms or a higher-quality manufacturing line. But a more innovative approach is starting to emerge as some suppliers rethink fasteners as products that just hold things together. Instead, these suppliers see mechanical fasteners as a way to improve the value proposition of the entire product or drastically improve manufacturing yields.

A couple of examples come to mind. Textron Fastening Systems, for one, has come out with an "intelligent fastening" technology. Called Intevia, this emerging fastening technology incorporates shape-memory materials and control electronics into a variety of mechanical fasteners — everything from latches to panel-fastening hardware. The shape memory materials, prodded by an electronic signal, are what engages and disengages the fastener.

According to Seshu Seshasai, Textron's technology vice president, the fasteners have interesting design implications. They can be actuated remotely, via wired or wireless connection. Remote activation, in turn, allows more design freedom for design engineers since these fasteners can go into areas that lack the access needed to install traditional fasteners or operate conventional access hardware components. The fastners can also be "reversible" for easier disassembly for revisions, repairs, or end-of-life recycling. Finally, Intevia intelligent fasteners, which have their own operating system that's compatible with many plant-wide automation systems, can use their "smarts" for jobs such as access control, data logging, and more.

Intevia fasteners are just getting off the ground now — literally. McCarthy Interiors Ltd., the first customer for the technology and a specialist in commercial aircraft interiors, is now flight testing Intevia latches that replace solenoid-based electro-mechanical latches. The earlier latches weighed more than twice as much, were noisier, and took up more than twice the space, reports Seshasai. (See http://rbi.ims.ca/4933-500 for more information on McCarthy.)

Other applications are in the works, not just in aerospace but also in industrial, appliance, automotive, and other uses. "We think intelligent fastening will change the way people think about fastners," Seshasai says.

Textron isn't the only one to take a different tack with its fasteners. In a very different market, PennEngineering has revamped the way some of its products are packaged for and installed in electronics manufacturing. The company has over the past year come out with several fastening products that go onto circuit boards as surface mount (SM) components.

The technology eliminates loose hardware because the fasteners are packaged on reels for automated surface-mount assembly with the electronic board components. And the SM fasteners require only small guide holes, rather the comparatively large broached hole for traditional board-mounted fasteners.

Big productivity advantages result. Jay McKenna, PennEngineering's special products manager, says that typical installation times on the SM line are under one second versus many seconds to manually screw traditional fasteners to the circuit board. The lack of a large installation also drives up yields, since broaching has been known to crack many a circuit board.

The company has already introduced SM components such as spacers and nuts. Just weeks ago, the company introcuded an SM version of its R-Angle, a component that can create right-angle attachment points on circuit boards. Like PennEngineering's other surface-mount products, the new R-Angle saves considerable amount of loose hardware. McKenna, special products manager for PennEngineering, says the SM saves at least two loose screws and loose nuts compared to a traditional angle bracket or right-angle block.

For more information, visit PennEngineering at http:// rbi.ims.ca/4933-501.