Series Production of Composite Leaf Springs

  Series Production of Composite Leaf Springs

Lightweighting technology: 65 percent weight savings with composite leaf
springs manufactured at Benteler-SGL by using Henkel’s Loctite matrix resin

Business Wire

SHANGHAI, China -- April 24, 2013

Henkel is combining its specialist expertise in the field of polyurethane
chemistry with the know-how of Benteler-SGL, one of the leading manufacturers
of composite components for automotive applications. The collaboration has
made it possible to mass-produce lightweight, fiber-reinforced leaf springs
based on polyurethane matrix resin.

The collaboration of Henkel and Benteler-SGL has made it possible to
mass-produce lightweight, fiber ...

The collaboration of Henkel and Benteler-SGL has made it possible to
mass-produce lightweight, fiber-reinforced leaf springs based on polyurethane
matrix resin. (Photo: Business Wire)

Lightweight construction technologies are steadily gaining ground in the
automotive industry as the weight savings they achieve in modern cars help to
significantly reduce fuel consumption and carbon emissions. Working with
Benteler-SGL, Henkel has developed a process for resin transfer molding (RTM)
of glass-fiber-reinforced leaf springs that uses a polyurethane matrix resin.
Compared to conventional leaf springs made of steel, these composite leaf
springs are up to 65 percent lighter.

With Loctite MAX 2, Henkel is offering a polyurethane-based composite matrix
resin that cures significantly faster than the epoxy products usually employed
for the RTM process. Due to its low viscosity, the polyurethane resin
penetrates and impregnates the fiber material more easily and less harshly,
thus enabling very short injection times to be applied. One special feature of
Loctite MAX 2 is its exceptionally high stress intensity factor, which is a
measure of toughness. This excellent toughness also has a positive effect on
the fatigue behavior under load. Leaf springs in cars are constantly subjected
to dynamic loading under driving conditions, so the use of flexible materials
with a high fatigue tolerance considerably prolongs the life of such

Resin injection processes such as RTM predominate in the manufacture of
automotive composites for mass-produced automobiles because they make it
possible to control the curing reaction more reliably, either by adjusting the
temperature or adding an accelerator. Furthermore, the risk of local
overheating and resulting shrinkage is reduced, as the polyurethane resin
Loctite MAX 2 generates less heat overall during curing than epoxy resins do.
As a result, even thick components with many fiber layers cure fast. The RTM
process is especially attractive for volume production of cars as fast curing
of the matrix resin permits short cycle times to be achieved.

The product range of Benteler-SGL, a joint venture of Benteler
Automobiltechnik and the SGL Group, includes body shell components such as
side blades, doors and visible carbon components. The composite components,
which are designed specifically for mass-production consist mainly of carbon
and glass fibers in various textile forms such as stitched or woven fabrics.
Customers include almost all the big names in the automotive industry,
primarily in the premium class.

Combined process technology expertise

“While developing these composite leaf springs, the competencies of
Benteler-SGL and Henkel complemented each other perfectly,” says Frank
Deutschländer, Global Market Manager Automotive at Henkel AG & Co. KGaA. “With
our matrix resin technology Loctite MAX 2, we were able to establish a new
process at Benteler-SGL that is tailored to the automotive industry and gives
this fiber composite component an attractive properties profile.”

Given the more stringent CO[2] exhaust standards, lightweight construction is
becoming ever more important for the automotive industry. The composite
components from Benteler-SGL help to reduce fuel consumption while offering a
high level of safety. “Thanks to our intensive collaboration with Henkel, we
have succeeded in producing a resin transfer molded glass fiber reinforced
leaf spring for the automotive industry that not only combines low weight with
high strength but is also mass production capable. It thus also satisfies the
highest expectations in terms of cost-efficiency and process reliability,”
says Frank Fetscher, Head of Sales and Marketing at Benteler-SGL Automotive

Photo material is available at

Photos/Multimedia Gallery Available:



Lisa Kretzberg, +49 211 797-56 72
Holger Elfes, +49 211 797-99 33
for Benteler-SGL
Gudrun Girnus, +43 662 2283 101040
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