P.J. PRAUSE DUROTEC GMBH - Federtechnologie mit Faserverbundwerkstoffen

S-Ply® is the registered name for composite leaf springs that are manufactured by Prause Durotec. The reinforcing material has a strictly parallel-oriented, non-interlaced glass or carbon fibre structure. The fibres are neither pre-stretched nor bent. In contrast to metallic materials with an isotropic structure, they are direction dependent and therefore can be aligned to suit the material structure.   Epoxy resin compounds are used as binding agents. Their special balanced composition ensures high adhesion to the glass fibre surface, resulting in optimum dynamic and electrical properties. The ratio of matrix resin and reinforcement fibres has been chosen to profit from all of the benefits offered by the raw materials selected to form the composite material.   The matrix fulfils a number of important tasks. It provides fixing for the fibre in the desired arrangement and supports it against buckling when under compressive stress.  In addition, it has good load carrying and transmissio

The laminated epoxy-fiberglass material Scotchply™, developed and patented in 1954 by the 3M company, has been processed by Prause Durotec into high performance leaf springs since 1974. Today, using the same improved fibre reinforced composite material, Prause Durotec processes and distributes composite leaf springs under the protected and registered product name S-Ply®.

Substitution of steel spring by S-Ply® leaf spring   Due to their  greater spring action, steel spring packages can be replaced by fewer or even one S-Ply® leaf spring for many applications.   Example:   a) Substitution   b) Cost calculation   Steel leaf spring: 155 x 25 x 2 mm 1 package of 10 springs   S-Ply® leaf spring: It is essential:   with: hS-Ply = Thickness of S-Ply® spring hStahl = Thickness of steel spring nStahl = Amount of steel springs EStahl = Modulus of elasticity (here 210.000 N/mm2) ES-Ply = Modulus of elasticity of S-Ply® leaf spring (here 28.000 N/mm2)   The result is that 10 steel leaf springs with a thickness of 2 mm each can be replaced by only 1 S-Ply® leaf spring with the thickness of 8,5 mm. Steel leaf spring* 10 pieces at 1,20 € = 12,00 € Intermediate package layers 18 pieces at 0,12 € = 2,16 € Total costs 14,16 € * purchase quantity > 1000 pieces, status 2009   S-Ply® leaf spring** 1 pc. at 4,13 € = 4,13 € shim plates (if applicable) 4 pc. at 0,12 € = 0,48

It is possible to have square as well as round shapes, drilled holes and slots from Ø2 – Ø30 mm, with counter bores and tapped holes. To reduce stress concentration and shearing stress when mounting, we recommend the reinforcement of the clamping areas by fixing glass reinforced laminate (GHGW) plates. GHGW-reinforcement plates can be purchased loose or attached to the leaf spring. A special two-component adhesive is applied for the bonding. Following images indicate possible spring shapes:

  S-Ply® is a glass-fibre composite material that is suitable for the highest dynamic requirements. The load carrying and supporting material is a strictly parallel-orientated, non-woven, glass- or carbon-fibre laminate (UD-prepregnated).     The glass-fibres are not stretched and not bent. In contrast to metallic materials with an isotropic structure, they are direction dependent and therefore can be aligned to suit the material structure. Epoxy resin compounds are used as binding agents. Their special balanced composition ensures high adhesive to the glass fibre surface, resulting in optimum dynamic and electrical properties. The ratio of matrix resin and reinforcement fibres has been chosen to profit from all the benefits offered by the raw materials selected to form the composite material.  The matrix fulfils a number of important tasks. It provides fixing for the fibre in the desired arrangement and supports it against buckling when under compressive stress. In addition, it has g