Transportation
Intelligent Fasteners
If you are facing that oft-quoted engineering truism, that a system
is only as good as its weakest link, consider the world's first, high-temperature-resistant,
"intelligent" fastener.
A product of Ultrafast, Inc. of Malvern, Pennsylvania, this fastening
technology was originally developed under a Small Business Innovation Research
(SBIR) contract managed by Marshall Space Flight Center. The NASA partnership
was born by a need for critical-fastening appraisal and validation of spacecraft
segments that are coupled together in space. In-orbit assembly requires
both lightweight wrenches for enhanced robot-arm mobility as well as remote
fastener-load inspection capability.
The space solution yielded an innovation that is likely to revolutionize
manufacturing assembly, particularly in the automobile building industry.
Ultrafast's "intelligent bolt" utilizes a piezoelectric thin-film
deposited directly on one end of the fastener. When electrically excited
by an Ultrafast tool, tensile loads can be accurately controlled during
the bolt tightening process. Insufficient bolt preload is usually the root
cause of joint failure resulting from joint separation, bolt loosening
or fatigue.
In effect, a bolt topped by the thin-film technology--at a cost of just
pennies per fastener--functions as a transducer for measurement and recording
of bolt tensile load. The coating itself is less than 0.001 inch thick
and is durable, deposited on the fastener by sputtering. This is a vacuum
process that has long found practical application in everything from integrated
circuits to reflective coatings on glass or decorative coatings on plastic.
Moreover, the coating can be applied to all forms of existing fasteners
without changing the basic design or metallurgy of the item undergoing
the process.
| Ultrafast's "intelligent" fasteners
are expected to be a boon to automobile manufacturers, assuring that more
precise loads are applied during bolt tightening. |
Ultrasonic measurements of a fastener are possible by using piezoelectric
thin films, in both longitudinal and transverse directions, heretofore
impractical in typical fasteners. Ultrafast technology uses the relationship
between the speed of ultrasonic waves in a material and the stress applied
to the material as its basis for computing load measurements. The idea
is that the "time-of-flight" of an ultrasonic signal traveling
in a fastener will increase as the load on the fastener is increased.
Ultrafast's intelligent-bolt technology deletes the self-defeating procedure
of having to untighten the fastener, and thus upset the joint, during inspection
and maintenance. Even the smallest fastener can be turned into latent sources
of information in numerous applications.
For the automotive industry, the advantages of applying the Ultrafast
system are distinct. Safety-critical components like powertrains, steering
systems and brakes can achieve higher reliability while minimizing service
costs and other impacts from joint failure. Use of high speed impact or
impulse wrenches to improve joint integrity and inspection can lower costs
in automotive body manufacturing by reducing joint assembly times.
Practical use of ultrasonic thin-film fasteners go beyond the realm
of automobile, aircraft, and space applications. For instance, from computer
disk drive assemblies to forklifts. In the nuclear field, from small flanges
to large pressure vessels. For chemical processing, critical-fastening
applications include offshore platforms to pipes. In construction, the
appeal of Ultrafast's innovation can be applied to buildings and bridges.
Ultrafast expects sales to exceed $100 million in a few years. Ultrafast
has licensed two major European tool companies to supply power tools for
automotive assembly and is establishing worldwide fastener coating services
through its Ultracoat subsidiaries.
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