Xtrac Suggests Specialty Steels for F1 Gearboxes Could Support Performance Improvements, Lightweighting and Downsizing in Commercial Transmissions
|Xtrac transmission components. Click to enlarge.|
The advent of new high performance steels for motorsport gearboxes developed by transmission specialist Xtrac—the latest specification of steel being required to significantly extend the life of a Formula One gearbox—could be broadly applied to a wide range of vehicles to improve their driveline reliability and efficiency according to Xtrac’s chief metallurgist Steve Vanes.
Xtrac, best known for the gearboxes and driveline components it develops for numerous motorsport formulas and high performance road cars, is joining a group of experts from industry and academia this week looking at cutting-edge technologies that could enhance the performance of transmission systems generally.
The seminar (Performance-Enhancing Technologies for Transmissions), which has been organized by the Aerospace Industries Division of the Institution of Mechanical Engineers in the UK, aims to transfer expertise between different transport sectors. The advanced techniques that can be used to improve gearbox performance and the technical knowledge conveyed will help facilitate the development of more efficient, reliable and competitive designs. The seminar is being held on 14 October 2009 at AgustaWestland Helicopters in Yeovil.
From a cultural point of view the world of motorsport has changed considerably, and the costs and relevance of its technology to wider consumer markets has become more important. For example, the trend towards engine downsizing in road vehicles to improve fuel efficiency and reduce CO2 emissions can be complemented by the downsizing of transmissions, requiring the intervention of new technologies and manufacturing processes for stronger and more lightweight components.
Vanes, who specialized in the heat treatment of steels with Lucas Industries and then worked on high tech bearings for Timken Aerospace, will present a technical paper at the seminar on Xtrac’s development of special steels for motorsport transmissions. The paper will cite the recent cost cutting measures in F1, which have lead to the development of a brand new specification of steel; necessary to extend the service life of gears, shafts, bearings, dog rings, hubs, selector forks, final drives and other highly stressed driveline components.
Previously, the typical life of a set of gears for a main shaft was approximately 350,000 cycles. The requirement to further extend the life of an F1 gearbox could equate to a life of more than 2.5 million cycles. Shifting the emphasis in F1 to endurance and reliability has the additional benefit of making the technology more relevant to road cars—as well as further hastening our steel development programme.
Over the years, Xtrac has progressively developed a whole family of special steels to meet various motorsport requirements, the most recent being for the increased longevity and fatigue resistance required in F1 gearboxes. Xtrac steels are tempered at higher temperatures than normal steels (200-350 °C compared with 140-150 °C), expanding the possibilities for surface enhancement processes such as physical vapor deposition (PVD is used in the manufacture of items ranging from semiconductor devices to coated cutting tools for metalworking), which require high temperatures that would affect the underlying hardness of normal steels.
The development of ultra high strength steels (up to 2,000 MPa), which can be tempered at temperatures more compatible with physical vapor deposition, extends considerably the range of low friction coatings and solid lubricants that can now be exploited—which in turn can have a significant impact on transmission efficiency and reliability.
Fundamental to the creation of a new specification of steel is our understanding of the interaction of the material’s innumerable physical and chemical properties with its heat treatment and the possibilities for sophisticated coatings and lubrication, which ultimately influences component performance. You might perceive it as standard practice, but in fact developing all new steels with the specific properties we require for race components is actually a fairly innovative concept even within the context of the motorsport industry. The process has evolved over the past 20 years, so we now have considerable experience in this field from our earliest evaluations, which gives us a clear picture of how alloy type and heat treatment affect mechanical and ultimately component properties. The underlying principles and processes we’ve developed can be applied to the automotive mainstream and other transport sectors including aerospace and would help to improve the efficiency of transmissions generally.
As well as understanding the interaction of the steel with its heat treatment, another fundamental relationship exists between the metallurgist and designer. In motorsport, the development of new materials and the design of components are always at the cutting edge. The feedback from races and analysis of parts is instant, which accelerates the whole development process. If a part doesn’t break then the designer is motivated to push the envelope even further; yet being even marginally over the limit will immediately reveal itself when a part does fail. This rapid pace of development is probably unique to motorsport and not only helps bring forward the development of new materials but also helps optimize the design of individual components.
Xtrac has developed its special motorsport steels in collaboration with Corus. The relationship with Corus Engineering Steels reaches back to the early 1990s with the introduction of the first bespoke steel by Xtrac (XVAR1), a vacuum arc re-melted version of the primary gear steel (En36C) then used in motorsport applications.