How mineral fibres work

The working mechanisms of our mineral fibres

The working mechanisms of our mineral fibres

Braking is the result of a surface interaction between brake disc and friction material surfaces like a brake pad. The mechanisms taking place at this contact area are a combination of physical, thermomechanical and chemical phenomenoa. Kinetic energy has to be converted into heat, plastic deformations, chemical reactions and wear debris.

Friction material

The performance of the brake system is influenced by the formulation of the friction material. A typical friction material consists of 10-20 raw materials. Each raw material has a unique chemistry, size and shape and therefore a unique functionality. Finding the right balance between these functionalities is crucial in the development of friction formulations.

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The main purpose of mineral fibres

Each raw material, including mineral fibres, has a specific function. The main purpose of mineral fibres is to facilitate other raw materials to work properly under any braking condition.

Why mineral fibres are used in friction material

Engineered mineral fibres from Lapinus are used all over the world in friction applications, in both NAO/non-steel and low steel formulations. Mineral fibres have an important effect on the micrometric scale at the surface of the brake material. They function as an anchoring point because of their specific shape and alignment in the friction matrix, specific hardness of 6 Mohs and high thermal and chemical stability. Because of these unique characteristics they are able to withstand high friction forces and the heat generated during braking, even if the energy load increases and mechanical reinforcement at the micro surface is necessary. Under these conditions mineral fibres remain stable, whereas other raw materials start to break down (e.g. organic materials) or oxidation reactions occur (e.g. steel fibres). These characteristics are fundamental because friction stability changes when the chemical composition of raw materials is modified.

Performance levels

The main fibre parameters that determine friction performance are fibre chemistry, dimensions of length and diameter, purity (shot content) specific surface treatment and coating. Research has demonstrated that the correct combination of properties is essential for optimum performance and depends on the field of application, formulation style and customer requirements. 

Mineral fibre properties

Mineral fibre property Average value
Fibre length [µm] 125 - 650
Diameter (num. avg.) [µm] 5.5

Non-fibrous material > 125µm [%wt]

0 - 30
Specific surface area [m2/g] 0.20
Hardness [Moh] 6
Melting point [°C] > 1000
Ignition loss [%wt] < 0.3
Moisture content [%wt] < 0.1
Specific density [g/cm3] 2.75

Synergy of raw materials

Mineral fibres can also be engineered for different contributions to friction formulations from a tribologic point of view. The final performance of the friction material always depends on the synergy between all raw materials.

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