Solid Height - Spring Manufacturers Institute

engineering alloys, make it the “ideal” spring material
for space- or weight-sensitive applications. For
many years, the aerospace industry, the original
prime mover in titanium development, has relied
upon the low modulus of elasticity, high strength
and low mass of Beta-C titanium (Ti-3Al-8V-6Cr-
4Mo-4Zr) for springs comparable in size to those
used by automobile and motorcycle producers.
However, Beta-C has an inherently expensive chemistry
and requires lengthy production steps. Its high
strength is achieved through long age treatments
(24-hour cycles for the finished parts are common)
or cold work steps, or both. This gives Beta-C a cost
structure that rules out consideration for volumeproduction
motor vehicle applications.
To meet the production cycle and cost requirements
of vehicle manufacturers, Timet developed
and patented Timetal LCB titanium (low-cost beta;
Ti-6.8Mo-4.5Fe-1.5 Al), which uses an altered alloy
formulation and a substantially less expensive Fe-
Mo (iron-molybdenum) master alloy than Beta-C. Its
high strength is attributable to alloy chemistry rather
than additional processing steps. Extended aging
and cold work steps are not required. Age times are
compatible with the thermal cycles available in the
existing infrastructure for steel spring processing.
In addition to being lower in cost than Beta-C, from
a structural efficiency perspective, meaning spring
response per unit of mass, the alloy’s low shear
modulus (45 percent less than CrSi spring steel)
combined with its high strength make Timetal LCB
an ideal spring material for vehicle applications.
Growing Spring Applications
The first automotive application of Timetal LCB
was as the rear suspension springs on the 2001
Volkswagen Lupo FSI, noted for being a small
automobile that achieved surprising performance
with very high fuel efficiency, due in part to its light
weight. More recently, again with the design objective
of reducing weight but for entirely different reasons,
the 2004 Ferrari Challenge Stradale became the first
production car to use Timetal LCB titanium suspension
springs throughout. Ferrari selected titanium
suspension springs to reduce vehicle weight, reduce
unsprung weight and improve performance.
Weight reduction on a motorcycle can have
as great an effect on performance as it can on an
automobile. However, to fully appreciate the meaning
of weight reduction on a motorcycle, the level
of difficulty in achieving it and its value to the
manufacturer, a comparison is useful: A one-pound
reduction on a 200 lb. high-performance motorcycle
would be equivalent to a 14.1 lb. reduction (a notable
accomplishment) on the already exceptionally light
Ferrari Challenge Stradale, which weighs 2,822
50 SPRINGS July 2006
lbs. By definition, however,
motorcycle engineers
have far fewer components
to even consider when
trying to reduce weight.
When viewed in this light,
it is easy to see why the
appreciation for titanium
by motorcycle and automobile
design engineers is
growing rapidly.
Increasing numbers of
manufacturers are recognizing
that titanium offers
proven and straightforward solutions to a variety
of weight-reduction and performance-improvement
challenges. Yamaha’s use of titanium in a range of
applications is visible, significant and has continued
to grow, and there is strong evidence that others are
learning from their positive experience.”
Kurt Faller is the president of Timet Automotive
in Morgan Town, PA, the automotive operation of
Titanium Metals Corp. (Timet). With headquarters in
Dallas, TX, Timet is a worldwide integrated producer
of titanium metal products. Information about Timet is
available on the Web site at www.timet.com. v