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Mechanical engineering:
HIGH-STRENGTH TUBES MAKES CAR SAFE
A project to design a new car model takes 2 to 4 years. When
the car is finally ready, it contains parts from hundreds
of suppliers. Each supplier is chosen after a thorough screening
process. Just getting into this process is a major investment
for suppliers.
Rautaruukki has passed the automotive manufacturers’
rigorous screening process and makes tubular products for
the safety structures of several cars. Typical applications
are the seat frames, side impact beams, airbag injection tubes
for inflatable curtains and structural tubes at the front
of the vehicle. Rautaruukki is the leading manufacturer of
the airbag injection tubes for inflatable curtains in the
whole of Europe. It can be said that Rautaruukki has specialized
in the safety structures of cars.
Rautaruukki makes different kinds of tubes and value-added
tubular products. That’s why Rautaruukki delivers tube
products to certain development partners, which produce the
final components for cars. Rautaruukki has this kind of development
partner in many countries, such as Sweden, Germany and France.
The list of Rautaruukki’s references includes car models
that are in high demand, such as all Volvo models, the Jaguar
X-Type, Saab 9-3/9-5, Mercedes-Benz C and E Class, Opel Astra
Cabriolet, Peugeot 307, Renault Laguna, Mégane, Espace
and Clio, Nissan Micra etc. The most recent applications are
tubes for the sub-frame structures, precision tubes for the
front bumper and rear axle and, possibly in the future, for
suspension systems as well.
For example, the front bumper has to meet impact from the
front and distribute forces to as wide an area as possible
in the front of the car. Therefore, it is made of ultra high-strength
rectangular tube. This is the first batch production order
in which Rautaruukki produces tubes whose tensile strength
exceeds 1,000 Mpa. This strength level can be reached directly
on the tube production line by using multiphase steels. Producing
these high-strength tubes requires great experience.
Challenging sector
Factors that affect the choice of subcontractors are their
corporate background and experience of their delivery reliability,
dependability and expertise. It is extremely important to
be already involved in the project when work starts on designing
a new car model.
To become a component supplier to the automotive industry
a sub-contractor needs to collect a wide range of information.
Simply having products with high technical qualities on its
own is not enough. Sub-contractors have to know and be able
to foresee the strategic policies of car manufacturers. Like
many other industrial sectors, the automotive industry has
consolidated. Despite the large range of makes of car available,
the number of actual players has fallen.
There are examples of different cars that hardly differ from
each other technically since they are made by the same manufacturer.
A typical feature in the automotive industry today is that
there are fewer suppliers who supply larger entities. In order
to differentiate their products, manufacturers use styling
and marketing means, creating a brand image for each make
of car and, for example, increasing driving comfort and safety.
Hydroforming – a new process for the automotive industry
For the automotive industry, which is used to processing material
by pressing, a vehicle component produced by hydroforming
is a new product. The typical “blank” for hydroforming
is a tube.
Bearing in mind the safety and environmental requirements
faced by the automotive industry in the future, it is extremely
likely that hydroforming will become the production method
of the future for vehicle components.
Using high-strength, longitudinally welded cold-formed precision
steel tubes in hydroformed vehicle components makes it possible
to achieve extremely cost-effective solutions that also meet
the performance, safety and environmental requirements for
cars.
The tubes used in the automotive industry are technically
quite difficult to make. The harder the material used, the
greater the importance of expertise in forming and welding
on the tube production line. Precise measurements, formability
and consistent quality from one batch to the next, are the
key properties that are required of tubes.
In the future an increasing number of the tubes needed by
the automotive industry will be manufactured from high-strength
steel, which may be cold- or hot-rolled. In addition, the
use of galvanized steel as the tube material will increase
in components that are exposed to corrosion.
The Renault Clio 16V is one of the cars with Rautaruukki
Metform precision tubes. The headrest of the car is made of
Rautaruukki’s tubes. A project to design a new car model
takes 2 to 4 years. When the car is finally ready it contains
parts from hundreds of suppliers. Each supplier is chosen
after a thorough screening process. Just getting into this
process is a major investment for suppliers.
Published 2003
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