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The manufacturing process of brake materials used for braking applications consists of a succession of steps among which the hot molding has a major impact on properties and performance of materials. In this paper, impact of hot molding temperature and duration on mechanical and thermal properties of friction materials developed with simplified formulation was investigated. Two different hot molding conditions were studied: condition 1 (low temperature associated to long duration) and condition 2 (high temperature associated to short duration). Braking behavior, thermo-mechanical phenomena and wear and friction mechanisms were also investigated. Results indicated that hot molding conditions did not significantly affect mechanical properties and tribological behavior, but they had impact on thermal properties (material molded according to condition 1, material A presented a higher thermal conductivity) and on wear mechanisms involved in the contact. In addition, results revealed that the studied hot molding conditions impacted thermal localization recorded during braking that was denser for the disc rubbed against material B (material molded according to condition 2).

The manufacturing process of organic friction material used for braking applications is of importance with regard to their properties and performance. This article deals with a friction material manufactured according to two different hot molding conditions. An original analysis of polymerization of the phenolic resin matrix led to the choice of temperature and duration of the hot molding process. Two materials were developed, changing the hot molding process according to these two dependent parameters, and their friction and wear behaviors were investigated for various thermal severities of sliding conditions. The thermal conductivity was also analyzed and found to be higher when the hot molding temperature was low and the hot molding duration was long. Wear test results showed that friction was not significantly affected by the process change. On the contrary, wear appeared to be sensitive to hot molding temperature and duration. Hot molding at elevated temperature for a short duration led to higher wear resistance because the rubbing conditions were not severe. On the contrary, hot molding at low temperature for a long duration was in favor of the wear resistance for higher severities of the rubbing conditions.

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The brake friction materials are composite materials with multi-ingredient systems which induce a complex formulation. This complexity is also the result of the manufacturing parameters effects, such as mixture sequence and duration, moulding pressure, time, temperature and heat treatment time. Therefore, heterogeneity is induced as well in the characteristics (microstructure, density, etc.) as in the behaviour (mechanical, tribological, dynamic, etc.). Despite the study of the effect of manufacturing parameters on the friction material behaviour, the synergistic effect between the heterogeneity and the braking performance is still not well reported. This paper strives to eliminate the cloud of uncertainty of the role of manufacturing parameters on the friction material performances by providing most used process of elaboration, and most required properties for contemporary brake system. Innovation in brake discs and pad manufacturing by optimized algorithms, prediction approaches, and 3D printing process is presented as innovative methods to improve braking materials performance.

Friction materials are composed of numerous ingredients which differ from nature and particles size. Each ingredient has its own impact on the mechanical and tribological behavior of the material. Brass ingredients have a great impact on the thermal gradient dissipation in the sliding contact between disc and brake pad material. In this research, the influence of different sizes and forms of brass ingredient was studied on the friction material behavior. The physical (density), mechanical (yield strength, young module) and thermal (thermal conductivity and specific heat) properties of the considered composites were characterized. Results proves that only physical and mechanical properties are sensitive to the changes in size and form of brass particles. The tribological behavior of the brake friction materials was also assessed using a pin-on-disc tribometer. The results show that bigger brass particles and their elongated shape allows it to be well embedded on the pad surface during braking application, and thus decreased wear rate . In contrast, the smaller particle decrease the friction stability and it rounded shape increase wear of the material since it tearing from the surface by abrasive wear.

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