Brake Pad Compressibility
The compressibility of brake pads consists of measuring the thickness change in μm under a defined uniaxial pressure or how much a brake pad can be pressed together. Pad compressibility can be an important design parameter of braking systems, which significantly impacts brake performance, comfort, and behavior that the driver experiences, as well as noise and vibration development. Among ingredients like phenolic resin, metallic and non-metallic fibers, fillers, abrasives or lubricants, which can be contained in brake pads, only a few are well known to directly affect compressibility, like graphite, rubber or so-called “Friction Dust”. To address this challenge, Superior Graphite has developed Resilient Graphitic Carbons (RGC™) that help control brake pad compressibility.
How can we help address your challenges?
Issue
Formulators have difficulties adjusting the compressibility of pads, which can negatively impact brake comfort as well as pedal feel and can cause unwanted vibrations.
Solution
RGC™ is a proven solution to increase cold and hot compressibility even with a limited addition of 2-3% in weight. RGC™’s increased porosity and resiliency assists in adjusting pad compressibility. In addition, the open surface porosity of RGC™ promotes a strong bond with the phenolic matrix, which results in the reduction of fading phenomena, especially at high temperature.
Issue
Some formulations experience excessive noise during the braking function.
Solution
Very often, noise is a result of vibrations occurring at different frequencies. An RGC™ addition at a range of 2-5% in weight, or in replacement of other graphite or CPC, reduces vibration and thus noise. This is attributed to its damping capacity, which is related to its unique morphology and porosity.
Nowadays, Brake Pad compressibility is specified by producers under different sets of conditions as requested by the automotive industry. As a result, the proper selection of raw materials, which are known to play the major role in compressibility, is becoming more and more critical. Over the last 15 years, Superior Graphite successfully introduced the concept of RGC™ into the market. Produced using our unique Electro-Thermal Treatment/Purification Technology, this material is commonly used by the largest OEM and OES producers. It is also being used by AM producers as a very easy way to achieve compressibility improvement in small or large brake pads, without too many other adaptations in the rest of the formulation or production process. A simple replacement of 2-3% in weight of synthetic and/or CPC with RGC™ can massively improve the cold and hot compressibility according to SAE2468 as can be seen under Fig 1.
Fig. 01
Change in Compressibility of NAO Formulation from Increased Ratio of RGC Material
