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Editor: John Mortimer
Monday, 17 August 2015
No downside to light-weighting – claims Jaguar
Dr Mark White, chief
technical specialist, lightweight vehicle technologies at Jaguar, and an
architect in helping Jaguar to pioneer the use of aluminium body-in-white (BIW)
structures claims: “There is no downside to light-weighting.”
have the expertise in aluminium body-shells, and now it’s about applying that
to our range of vehicles and showing the benefits to customers. We’ve made the
all-new Jaguar XF (below) even better: we’ve improved the weight, stiffness, crash
performance, fuel economy, handling and refinement,” he adds. “The all-new XF up to 190kg lighter than its
Some of the
weight-saving however is attributable to the 2-litre Ingenium diesel not
features in the previous model. And some might see the associated energy balance and life cycle cost as being two down-sides of aluminium and which have to be assessed against greenhouse gas (GHG) emissions.
However, Jaguar sees aluminium
alloys, self-piercing rivets from Henrob and structural adhesives are the
essential elements around which every Jaguar is designed.
Used to create
inherently light, stiff body structures, they enable the highest standards of
performance, efficiency, safety and dynamics, claims the company.
attributes were engineered into Jaguar’s aluminium-intensive architecture from
the beginning. And it is from this state-of-the-art modular structure that the
all-new XF was developed,” the company adds. “Also featuring advanced
high-strength steels, the aluminium-intensive monocoque uses materials
intelligently, exploiting each to its full potential.”
also used to make the bonnet and front fenders, while the front-end carrier and
cross-car beam are cast from lighter magnesium alloys. Combined with the other
weight savings made throughout the vehicle, this makes the all-new XF up to 190kg
lighter than its predecessor.
“The move from
an all-steel to aluminium-intensive monocoque leverages more than a decade of
experience of manufacturing luxury cars from aluminium in high volume,” notes Jaguar, before adding that the one-piece
bodysides of the all-new XF are testament to Jaguar’s “world-leading expertise
in working with the material”.
Stamped from a
single sheet of high-strength 6000-series alloy, the bodysides weigh less than
6kg. Jaguar engineers claim the bodysides are among the most
technically-challenging panels Jaguar has developed and push the limits of what
is possible in terms of design and manufacture in aluminium.
deep haunches and the sixth-light incorporated all of the learning from F-TYPE
in terms of depth of draw and tightness of radii,” claims Jaguar engineers.
Assembly to the
rest of the structure uses a two-stage framing process. The technique allows
for greater joint efficiency through optimised positioning of the rivets. This
translates to increased torsional rigidity of the body, and the all-new XF is
up to 28 per cent stiffer than its predecessor.
as the high-pressure die-cast aluminium front suspension towers increase local
stiffness and make a significant contribution to the all-new XF’s benchmark
ride, handling and steering.
Much of the
improved refinement comes from reducing structure-borne noise. Critical to this
is that the body behaves as a homogeneous structure: wherever vibration energy
finds a discontinuity it will concentrate and then radiate noise through to the
Each part of
the body has been analysed to ensure that as many potential sources of noise could
be designed-out. In some areas, such as the crash structure behind the front
bulkhead, fully-sealed, double-wall structures are used.
deadening has been applied, the latest spray-on materials are used due to their
combination of higher performance and lower weight.
inside the aluminium sections also contribute. These pieces are fitted during
assembly: as the body passes through the e-coating ovens the heat causes the
foam to expand so that it completely fills the section.
example of attention to detail which delivered the all-new XF’s benchmark low
levels of cabin noise is typified by the way in which the high-level brake
light is fitted to the body. Running all the way along the full length of the
rear screen, this LED light has a seal and an acoustic barrier behind that to
minimise any noise leakage through to the interior.
pressings used where stiffness is a key criterion, such as underframe reinforcements,
are typically formed from 5000-series alloys. These include RC5754, a grade
unique to Jaguar Land Rover, and which is made predominantly from recycled
Around half of
this is scrap sourced from the press shops, helping not only the move towards
closed-loop recycling but also reductions in overall electricity consumption
and therefore lifecycle CO2 emissions. Innovations such as this are a
further example of Jaguar Land Rover’s world-class aluminium expertise and
drive for environmental sustainability.
engineers claim the latest XF has been engineered to meet the most demanding
crash test requirements. As part of the intelligent material mix in the body,
the rear longitudinal members and the B-pillar reinforcements are made from
ultra-high strength hot-formed boron steels, providing exceptional rigidity and
stability of the occupant safety cell.
protection benefits from the more vertical front grille and the improved
energy-absorbing properties of the front bumper, enhanced even further by
Jaguar’s latest-generation deployable bonnet technology.
believe the all-new XF is the best looking car in its class. Elegant, handsome
and with proportions that imbue a great sense of integrity – the all-new XF is
true to the great tradition of sporting Jaguar saloons while being completely
of its time,” boasts Ian Callum, director of design, Jaguar.
the 2007 XF was “a radical step forward for Jaguar – and for the business car
segment”. Combining a sleek, coupé-like exterior and a luxurious interior, “it
set the class benchmark for aesthetics and driving dynamics”, it adds.
The new XF
retains its predecessor’s core attributes, but uses Jaguar’s
aluminium-intensive architecture to enable weight savings of up to 190kg –
making the 163PS diesel model 80kg lighter than the nearest competitor – plus
an increase in torsional stiffness of up to 28 per cent.
architecture also delivers dramatic improvements in packaging and the
proportions so essential to Jaguar design,” according to Jaguar.
The new XF is
4,954mm long: at 2,960 the wheelbase is 51mm longer than before, the front
overhang 66mm shorter. Though 7mm shorter and 3mm lower than the original XF,
rear seat space is class-leading thanks to 15mm more legroom, 24mm more knee-room
and up to 27mm more headroom than before. Aerodynamics have improved with the
drag coefficient down from 0.29 to 0.26.
The new XF is
the first Jaguar to offer adaptive full-LED headlights. Featuring two banks of
LEDs and reflectors – one for dipped beam, the other for main beam – they
generate light with a colour temperature closer to that of daylight than is
achievable with Xenon lights, delivering better illumination, according to the
company. At the same time, energy consumption is reduced. Unlike
first-generation designs, cooling fans are not needed.
The new XF
powertrain range consists of the 163PS and 180PS 2-litre Ingenium diesels from
the company’s Wolverhampton plant teamed with either six-speed manual or
automatic gearboxes (offering 104g/km); RWD 300PS (700Nm torque) 3-litre V6
diesel (with its compacted graphite iron - CGI - vee block) with a ZF automatic transmission; and the RWD supercharged 380PS 3-litre V6 petrol driving
through an eight-speed ZF automatic.