Henry Ford called the Model T "the universal car" because it was low-cost,
easily maintained, and could successfully travel the roads of the time. Because
it was the first low-priced, mass-produced automobile with standard,
interchangeable parts, Model T quickly became every man's car. By October 1911
Ford opened an assembly plant in Manchester, England, its first outside North
America, and by the end of 1913 had signed contracts to sell the Model T in
China, Indonesia, Siam, Dutch East Indies, and Brazil.
The all new Ford Focus, like the Model T, is one of the most significant
global platforms Ford has ever launched. First manufactured and introduced in
Europe, this summer Ford began North American Focus production for its
2000-model-year introduction. In all, Focus will be sold in 60 different
countries, according to President of Ford Division Jim O'Connor.
ZTS(Zetec Touring Sedan):
Pricing includes $415 destination and delivery charges.
In engineering the first vehicle of the Ford 2000 program, the Focus team had
at its disposal all of Ford's worldwide resources. The goal: design a global
platform that's easily modified to suit local markets. "Focus is one of the most
intensive, CAE-driven programs Ford has ever launched," says Ford Focus Body
Engineering Manager Graham Curle.
To compete, the car must offer improved crash-worthiness; refinement in terms
of noise; vibration and harshness (NVH); and be able to comfortably accommodate
drivers of all shapes and sizes. Apparently it does, having won the 1999
European Car of the Year by almost 200 points, according to O'Connor. "Focus
raises the bar for small cars in terms of roominess, comfort, driving dynamics,
and safety," says Curle.
Focus' platform is available as a 3- or 5-door hatchback, sedan, or wagon
,which, like the Model T, share many interchangeable parts. Front-end structure
and design, as far back as the fuel tank, are common to all four body styles.
Ford's multifunctional optimization (MFO) software, which incorporates I-DEAS
Master Series from SDRC (Milford, OH), helped the Focus team optimize package,
driving dynamics, comfort, fuel economy, and cost of ownership. MFO software
allows engineers to look at NVH, weight, and safety as a complete entity rather
than exercise each aspect independently with separate CAE tools.
To achieve the superior ride and handling of a fully independent rear
suspension while keeping the cost down, engineers made extensive use of
pressed-steel components in the rear suspension, and reduced friction and
compliance in the front suspension and steering. But driving dynamics ultimately
depend on a stiff structure. By applying the latest laser-welding technology to
key body components, engineers designed a platform that's twice as stiff as its
predecessor, and 15% stiffer than all recent class entrants.
Tailor-welded blanks. Tailored, laser-welded blanks are to
Focus what vanadium steel was to the Model T. Childe Harold Wills'
experimentation with the properties of vanadium steel, an alloy manufactured for
the company at the direction of Henry Ford, gave the Model T great strength and
durability without extra weight. The result was a lightness and durability
characteristic of the Model T that was key to the vehicle's long-term success.
Likewise "tailored blanks allow Focus to be much more robust for its weight,"
To achieve a stiffness of 826 kNm/rad, Focus' structure uses
variable-thickness steel rather than exotic materials. Today's laser-welding
technology offers the ability to join steel panels of different gauges to
provide tailored blanks for stamping processes. "This gives engineers greater
freedom in design by thinking in terms of larger parts and part consolidation,
without weight penalties or restrictions in construction of multi-piece
assemblies," says Ford Focus Chief Program Engineer Tony Pixton. In addition to
weight savings, laser-welded blank technology enables fine-tuning of deformation
characteristics, provides strength where it is required, and allows down gauging
where it is not.
But tailored blanks aren't a carte blanche solution. Focus engineers
carefully considered investment vs piece-cost efficiency, and kept targets for
safety, durability, NVH, and weight in mind when determining if using a
laser-welded blank for a particular part would be a plus on the bottom line.
"For example," Curle says, "a certain combination of panels may offer a weight
savings, or NVH improvement that would result in as good as crash performance,
and have no effect on durability."
The rear side rails, for example, are traditionally made from four separate
parts, according to Curle, "For Focus, these parts are replaced with a single
laser-welded blank, with a three stage gauge change." Tailoring the blank prior
to stamping allows the side rail to have a thinner gauge to improve weld
strength near the passenger compartment. The heaviest gauge in the middle
provides rigid mounting points for the suspension, and then a different gauge to
optimize the rear crush structure, while simultaneously saving more than 1 kg
per rail in weight. "Laser-welded blank technology allowed us to optimize in
terms of weight, manufacturing assembly, and rear crash performance," says
Curle. "With tailored blanks you can put the weld lines where you want them,
keep them out of a plane of stress, and achieve the desired crash performance
without having to add any local stiff areas."
Similarly, the gauge of steel in the B-pillar is 2.25-mm thick at the top but
tapers to just 1.1 mm at the base, providing a stiff upper section for superior
performance in the event of a side-impact crash. "We needed a very stiff
B-pillar so that it would deploy at a certain rate," Curle explains, "but at the
same time, we wanted it to pivot around the rocker so that it wouldn't buckle,
bend, or collapse prematurely." A tailored blank let engineers design a small
thinner gauge area at the root of the B-pillar joint that allows it to rotate,
but still remain intact. Not rip the B-pillar off the rocker for example, but
allow it to deform at a fixed speed and not increase in velocity. "We wouldn't
have been able to get that kind of performance with conventional joining
methods. Laser welding was the only way we were able to achieve this rotation at
the base of the B-pillar, achieve the stiff structure, and hit the targets that
we wanted," says Curle.
From a vehicle dynamics standpoint, Focus' highly rigid platform (boosted
further by cross-members front and rear) has enabled engineers to fine-tune the
front and rear suspension systems to deliver driving precision and ride comfort.
"The goal was to give Focus a level of comfort, refinement and active safety
normally associated with larger cars in a higher class, while providing handling
and stability of a more sporty and reassuring nature," says Pixton.
Tailored blanks tackle tough design problems
Government legislation, environmental pressures, safety regulations and
consumer dictates during the past two decades have pressured engineers to design
lighter more fuel-efficient cars that produce lower emissions, and to deliver
improved handling and crashworthiness. Tailored blanks are generating a great
deal of interest in the automotive industry for their ability to reduce mass and
cost, while improving structural integrity and material utilization. Although
tailor-welded blanks were first developed to reduce waste by using collectible
offal, today engineers use tailored blanks to fine-tune deformation
characteristics, provide strength where it's needed, and down gauge where it's
Engineers typically use tailor-welded blanks made of sheet steels with
different thicknesses, coatings, and properties in bodyside frames, door-inner
panels, motor-compartment rails, center-pillar inner panels, and
wheelhouse/shock tower panels. Numerous tailored blank applications currently
are under consideration in North America and worldwide. At present, European
carmakers, including Volvo, Mercedes-Benz, BMW, and Volkswagen, and Japanese
carmakers, including Nissan and Toyota, use tailored blanks.
The cost to weld a tailored blank depends on the product design and welding
system. In general, when looking at the welding cost for 25 mm (1.0 inch) of
weld, the following are true:
Short welds cost more than long welds
Two identical parallel welds are approximately twice the cost of one weld
Heavy or coated steels are more costly than lighter or uncoated steels
Thicker gauge combinations cost more than thinner combinations
In-line welds cost slightly more than a continuous weld.
Tailored blanks offer engineers greater freedom to design larger parts
and reduce the number of components without weight penalties or
restrictions in construction of multi-piece
Additional details...Contact Jack Noel, Auto/Steel Partnership, 2000
Town Center, Ste., 320, Southfield, MI 48075-1123; Fax: (248)
Metal/plastic composite solves 'no-build' problem
Just 30 months before the Focus was due to launch in Europe, the manufacturer
found itself in a no-build situation with respect to the Focus' front-end
assembly. It was impossible to achieve the required quality with respect to gaps
and flushness in the front end of the vehicle due to tolerance stack up in the
multipiece, sheet-metal assembly.
During a combined workshop, Bayer Corp.'s Polymers Div. developed a solution:
Replace existing sheet metal parts with one extremely accurate metal/plastic
composite part that installs on the body's construction line. The part adjusts
exactly to the outside fender lines in x, y, and z directions, and is square in
x and y.
To achieve the necessary precision, this hybrid GOR (grill opening
reinforcement), as it's called, uses mounting brackets for adjustment and is
comprised of three sheet metal parts -- the upper cross-car member, the lower
cross member, and the shield for the hood latch and lock cylinder. These are
joined together by an injection-molded rib structure (nylon 6, 30% glass filled)
to form a strong body component. Connection between the sheet metal and the
plastic structure is purely mechanical, with sheet metal left partially exposed.
The new GOR assembly and accurate adjustment in body construction eliminates
the accumulated tolerances of the underbody front end. "Even if the underbody is
matchboxed," explains Ford Focus Chief Program Engineer Tony Pixton, "the upper
body parts are accurate in gap and flushness and are square. Essential for the
Focus front end's long, clearly visible gaps, the concept of positioning and
fixing all front-end exterior components such as fenders, radiator grille,
headlamps, bumper skin and hood to one single highly integrated part saves much
money and assembly time."