Source: Excerpted from the article written by Peggy Malnati posted on CompositesWorld concerning what the manufacturer, Boge Rubber & Plastics, claims is the first commercially produced composite brake pedals.
DAMME, Germany – Boge Rubber & Plastics Group is producing what it says are the lightest, least costly and strongest all-composite brake pedals in the world, and the first in commercial production.
The Tier 1 supplier currently produces a quarter-million brake pedals per year for four vehicle platforms produced by German automakers and the system could produce up to one million pedals annually.
This is significant because the pedals are structural, are required to meet the same rigorous performance requirements as incumbent steel and aluminum, and the designs feature three different types of glass-reinforced thermoplastic composites.
Three materials increase fiber efficiency
To keep pedals light, thin, cost-effective and capable of meeting challenging original-equipment manufacturer (OEM) specs, Boge uses continuous glass fiber organosheet as the shell structure to carry the part’s main loads, which can be as high as 3,000 newtons.
Organosheet blanks are supplied precut to size, with two or three layers fully consolidated by supplier Lanxess Deutschland GmbH. To reinforce the main load paths on the organosheet blank, Boge adds strips of unidirectional (UD) glass fiber tapes in orientations and layups based on finite-element simulation results.
To do this, Boge uses software it has modified, and material cards the company has developed with its suppliers based on stress/strain curves measured for each material under temperature and humidity conditions specified by OEM customers. To add functional geometry, Boge uses overmolded chopped glass fiber compounds (from multiple suppliers) to provide structural ribs and attachment features.
All materials feature matrices of precolored black polyamide 6 (PA6), a tough polymer widely used in the automotive industry. Should OEM specs require such, Boge also has the option to use a higher temperature, less hygroscopic PA6/6 matrix in the overmolding compound, since both polymers are similar enough to bond to each other.
By using three different types of composites with glass reinforcement in three different forms, Boge can place fiber precisely where needed to meet performance requirements while avoiding over-engineering. The carry-on effect of this hybrid-composite approach is that it reduces material usage, nominal wall thickness, cycle time and overall part cost.
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