Rock wool, a fibrous material made from natural minerals, has increasingly found its application in the production of clutch facings. As an essential component in clutch facings friction materials, it significantly impacts the performance and quality of the final product. Rock wool is incorporated into clutch facings mixtures and clutch facings mixes, playing a crucial role in enhancing the overall characteristics of clutch facings.

Rock wool is mainly added to the clutch facings mixture to improve its thermal insulation, sound absorption, and mechanical strength. In the clutch facings production process, it acts as a reinforcement material within the clutch facings mixes. Generally, the content of rock wool in the clutch facings mixture ranges from 15% – 35% by weight, depending on the specific requirements of the clutch facings.

One of the most remarkable features of rock wool is its outstanding thermal insulation property. In a thermal conductivity test, the thermal conductivity of clutch facings with rock wool was measured to be as low as 0.03 – 0.04 W/(m·K) at room temperature. This low thermal conductivity effectively prevents heat transfer from the clutch during operation, protecting other components from high – temperature damage. For example, in a high – performance vehicle clutch system, the use of rock – wool – enhanced clutch facings can reduce the temperature of adjacent parts by about 20 – 30°C under high – speed and high – torque conditions.

Rock wool also exhibits excellent sound – absorption capabilities. In a sound – absorption coefficient test, the sound – absorption coefficient of clutch facings with rock wool reached 0.8 – 0.9 in the frequency range of 1000 – 3000 Hz. This is crucial for clutch facings as it can effectively reduce the noise generated during the clutch’s engagement and disengagement processes, providing a quieter driving experience.

Rock wool reinforces the clutch facings, enhancing their mechanical strength. In a tensile – strength test, the tensile strength of clutch facings with rock wool was increased by about 20% – 30% compared to those without rock wool. This improved mechanical strength enables the clutch facings to withstand higher mechanical stresses during operation, reducing the risk of wear and damage.

Although rock wool has many advantages, it is relatively brittle. When the clutch facings are subject to repeated bending and shearing forces during the clutch’s operation, the rock – wool – containing clutch facings may experience fiber breakage. In a fatigue – resistance test, after 50,000 engagement – disengagement cycles, the number of broken rock – wool fibers in the clutch facings increased by about 15% – 20%, which may gradually affect the performance of the clutch facings.

Rock wool has a certain degree of hygroscopicity. When the humidity in the environment is high, rock wool in the clutch facings can absorb moisture. In a humidity – absorption test at 80% relative humidity for 48 hours, the moisture content of rock – wool – containing clutch facings increased by about 5% – 8%. Moisture absorption may lead to a decrease in the mechanical strength and thermal insulation performance of the clutch facings over time.

In conclusion, rock wool offers significant advantages in the production of clutch facings, especially in terms of thermal insulation and sound absorption. However, its brittleness and hygroscopicity need to be carefully addressed when choosing materials for clutch facings friction materials. Further research and development are required to optimize the performance of rock – wool – based clutch facings.