In cooperation with LANXESS and Bond-Laminates GmbH from Brilon, Germany, ZF Friedrichshafen AG has developed a brake pedal based on nylon composite sheet and polyamide 6. The big advantage of this system is that it is 50 percent lighter than comparable brake pedals made of steel, but has the same mechanical strength. Weighing just 355 g, this concept component is the world's first car brake pedal made of polyamide reinforced with continuous glass fibers that is suitable for large-scale series production. “The brake pedal is a good example of the tremendous opportunities being opened up by thermoplastic composite structures in the drive to Green Mobility,” explained Thomas Malek, an expert in hybrid technology at the LANXESS Semi-Crystalline Products business unit. The newly designed brake pedal can be used not only in conventional passenger cars, it is also ideal for electric vehicles where weight must be kept to an absolute minimum to ensure the maximum range per charge cycle.
Fewer process steps
The brake pedal in nylon composite sheet hybrid technology is easier to manufacture than comparable pedals of sheet steel, which usually consist of several sheets. For example, the new technique eliminates the need for the complicated forming, cutting and welding processes required with sheet metal. Anti-corrosion treatment is now also superfluous because the plastic part does not contain any metal.
The brake pedal is made of a nylon composite sheet from the Tepex dynalite range from Bond-Laminates. The 2 mm thick nylon composite sheet material of polyamide 6, reinforced with 47 percent continuous glass fibers by volume, is heated, thermoformed and cut to size. The result is an insert, reinforced at specific points with Durethan BKV 30 H2.0 polyamide 6 from LANXESS, which has proved its mettle in hybrid technology. “The brake pedal could, in fact, also be produced in a single-step process because the forming of the nylon composite sheet could be easily integrated into the injection molding tool. This one-shot process allows high volumes to be produced economically,” said Malek. A further cost-reducing factor compared with an all-steel solution is that injection molding allows a wide range of functions to be integrated directly into the component. Typical examples include the pedal foot plate, attachments for the booster rod, and components for the brake light switch.
Material bond provides outstanding load resistance
Polyamide 6 is used as both the injection molding material and the matrix of the nylon composite sheet. In contrast to hybrid technology with sheet steel, the matrix and back-injected areas produce a material bond across all contact surfaces. It acts like a weld, and thus significantly increases the mechanical performance of the component. “This is one reason why the new brake pedal more than satisfies the requirement specification,” said Marek.
HiAnt – precise simulation of the nylon composite sheet forming process
LANXESS provided ZF with considerable support with the conception and computer-assisted design of the brake pedal. These services are part of the HiAnt brand, in which the Semi-Crystalline Products business unit has pooled the know-how it has developed in materials, design, simulation and process technology to deliver tailored customer service. For example, the forming process was simulated in order to calculate local differences in fiber orientation in the formed nylon composite sheet and optimize these fiber orientations as appropriate for the load on the brake pedal. The results went into a new material model that accounts for the anisotropic material behavior of nylon composite sheet. “We are able to calculate all the chief properties of nylon composite sheet hybrid parts, such as their crash behavior. It enables us to design parts such as this on the computer – quickly, cost-effectively and in consideration of the appropriate loads,” explained Marek.
Green Mobility – a core strategic topic at LANXESS
This year, LANXESS is focusing its activities on the core strategic subject of Green Mobility. The aim of the campaign is to focus on innovative technologies and products with which the specialty chemicals group can help to enable resource-saving, environmentally friendly, sustainable mobility, such as lightweight construction concepts for body parts or high-performance rubber for the manufacture of smooth running, fuel-saving Green Tires.
LANXESS (lanxess.com) is a leading specialty chemicals company with sales of EUR 7.1 billion in 2010 and currently around 16,100 employees in 30 countries. The company is at present represented at 47 production sites worldwide. The core business of LANXESS is the development, manufacturing and marketing of plastics, rubber, intermediates and specialty chemicals. LANXESS is a member of the leading sustainable indices Dow Jones Sustainability Index (DJSI) World and FTSE4Good.