Steel to Gain Market Share in Engine Crankshaft Applications
10 October 2000
Steel to Gain Market Share in Engine Crankshaft Applications, Reports American Iron and Steel Institute
Material's ability to reduce weight and improve performance encourages growth
DETROIT, Oct. 9 The use of bar steel in crankshafts will
increase by as much as 50 percent, from 40 to 60 percent of the market share,
by mid-2002 because of the material's capability to improve engine performance
and reduce weight, at economical costs, according to a recent study by
American Iron and Steel Institute (AISI) Bar and Rod Market Development Group
(BRMDG). This growth would be at the expense of cast iron, which currently
possesses 60 percent of the crankshaft market.
The BRMDG initiated the study, "Steel's Technical and Economic Progress in
the Production of Lighter and Smaller Engine Components," in 1998 in response
to the automotive industry's quest to increase fuel economy, reduce costs and
weight, and improve customer satisfaction. The report provides an in-depth
look at how crankshafts produced from bar steel forgings contribute to
achieving these goals.
Additionally, the report explains that this potential increase in steel
market share is due to innovative steel forming and processing technologies
that have advanced the state of the art during the past decade. "This study
points to the continued realization that steel is the material of choice for
the many challenges facing automakers today, including engine applications,"
said David Anderson, manager Bar and Rod applications, BRMDG. "With
innovative technologies and modern engineered steels, the steel industry is
helping automakers produce lighter vehicles that achieve improved performance
at economical costs."
Improved Performance:
An engine crankshaft attaches to connecting rods, which fastens to
pistons, and transfers engine power to the transmission. Forged steel
crankshafts offer a host of benefits compared to cast iron units including
greater durability, improved Noise Vibration Harshness (NVH) characteristics
and higher load-bearing capacity for torque at lower engine speeds (RPMs),
resulting in fuel efficiency improvements.
These benefits are the result of steel's unique mechanical properties,
such as a high ratio of yield point to tensile strength, which determines the
degree of rigidity and elasticity. Compared to cast iron units, these
properties of forged steel crankshafts provide a higher level of rigidity and
fatigue which provides better intrinsic dampening, enabling the engine to run
more smoothly, resulting in less vibration, less noise and, thus improved
customer satisfaction.
Additionally, better mechanical properties contribute to higher static and
dynamic rigidity which results in a higher load-bearing capacity for torque at
lower RPMs. Static and dynamic stiffness reduces distortions and lowers the
excitation energies from moving engine parts, ensuring significant fuel
consumption savings because the engine is producing the same output at a
reduced effort. Automakers currently using forged steel crankshafts include:
Ford Motor Co., DaimlerChrysler, Honda, British Leyland, Saab, Volkswagen,
Mitsubishi and Volvo.
Lightweight:
As automakers strive to reduce weight in vehicles, the powertrain
continues as a key focus in helping achieve that goal. Using forged steel-in
place of cast iron-reduces the mass of the crankshaft by eight percent
according to Krupp Gerlach, an automotive component manufacturer that recently
completed a study demonstrating the benefits of forged steel compared to cast
iron crankshafts in an actual series production engine. The crankshaft's
total length is also reduced by nine percent as a result of steel's unique
mechanical properties, particularly the ratio of yield point to tensile
strength.
This reduction in size and weight offers engineers greater design
latitude, resulting in more efficient use of space and material. Vehicle
makers correspondingly can reduce the size and mass of other powertrain
components, such as bearings and pins, further reducing weight, boosting fuel
economy and improving performance.
Costs:
The new generation of steels, including vanadium microalloys and Air-
Cooled Forging Steels (ACFSs), features improved strength and fatigue
properties, enhanced machinability and greater consistency due to specific,
controlled testing processes (sensitive to defects) performed during each
production phase. These improvements enable forgers to produce crankshafts
that are near-net shape, reducing production cycle and try-out times and, in
turn, costs as there is less need for machining and rework. Additionally, the
development of ACFSs has eliminated the need for heat treating, further
reducing the forged component costs. Using highly controlled heat processes,
ACFSs eliminate hot and cold spots on the steel bars, providing greater
product consistency, with more uniform grain size and microstructure. As a
result, these steels have increasingly replaced heat-treated steels in
crankshafts and other powertrain applications.
Benefits vs. costs:
Modern engineered steels, coupled with innovative processing and forming
technologies, have significantly decreased the manufacturing costs associated
with producing forged steel crankshafts. The strides made to reduce these
costs continue to boost steel's position as an economical material for use in
engine crankshaft applications. In addition to reduction in costs, steel is a
viable material for engine crankshaft applications because of the multitude of
benefits it offers, including:
* Light weight
* High performance
* Greater torsional stiffness
* Improved NVH characteristics
* Greater durability
* Net or near-net shape
* Less machining
* Less or no rework
* Lower rejection rates
* Greater consistency and product repeatability
* Inspection simplicity
* Fewer warranty claims
* Improved customer satisfaction
"As the steel industry continues to make technological advancements,
forged steel crankshafts will improve in quality, performance and cost making
them even more viable for engine applications," said Jurgen Kneller, author of
the study.
To obtain a copy of this study, contact Dr.-Ing Jurgen Kneller, at
J.Kneller@gmx.de or David Anderson, manager Bar and Rod Applications, AISI at
248-945-4764. To learn more about the BRMDG, visit steel.org .
Under the auspices of the American Iron and Steel Institute, the Bar and
Rod Market Development Group strives to grow the market for value-added steel
bar and rod products. The Group pursues this goal through two task forces
committed to developing innovative solutions to the challenges facing their
clients and the steel industry. These task forces include:
* Automotive/Heavy Equipment
* Construction/Infrastructure