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How Paper-Based Friction Materials Power Modern Machinery

The Ubiquitous "Safety Guardian"

Have you ever wondered what enables everything from roaring construction machinery to agricultural machinery plowing the fields to industrial equipment shuttling through factories—the precise starting, smooth operation, and reliable braking they achieve?

The answer lies in a seemingly insignificant yet crucial core component: friction material. It acts as the "safety guard" and "power link" of machinery, ensuring every brake is safe and effective, and every power transmission is smooth and flawless.

Among the vast family of friction materials, wet friction materials are becoming the new favorite in modern machinery due to their exceptional reliability, safety, and exceptionally long lifespan. Among wet materials, paper-based friction materials stand out as a leading force thanks to their excellent overall performance, cost-effectiveness, and broad application prospects.

Today, let's delve deeper into the fascinating world of this "unsung hero"—paper-based friction materials.

What is Paper-Based Friction Material? — A Sponge-Like Power Core

Imagine a "sponge" with countless tiny pores—that's the most intuitive image of paper-based friction material.

It is a material with a reticular porous structure composed of three core components: reinforcing fibers, functional fillers, and a binder resin. This unique structure gives it extraordinary capabilities:

• Oil Storage Capacity: The porous structure acts like a miniature "oil depot," capable of storing large quantities of lubricant.
• Dynamic Lubrication: When the friction plate and mating plate engage and are subjected to pressure, the lubricant within the material is instantly squeezed onto the friction surface, forming a tough lubricant film, enabling smooth, gentle "wet" friction.
• Self-Recovery: When the friction plates separate, the material rebounds like memory foam, "absorbing" the lubricant back into the pores, ready for the next operation.

It is this dynamic cycle of "oil storage-oil squeezing-oil return" that allows paper-based friction materials to perform well in an oil bath environment, achieving a perfect combination of high durability and stable friction performance.

Exploring Core Performance: How Do Three Key Factors Affect It?

The performance of paper-based friction materials is not static. Like a top athlete, its performance is influenced by the "field," "equipment," and "condition." Let's examine how these three key factors shape its performance.

Factor 1: The "Stage Effect" of Lubricants

Paper-based friction materials are highly sensitive to lubricants, and different lubricants create distinct "stages" for their performance. Even the same friction material can exhibit significantly different friction characteristics (especially the kinetic friction coefficient) when exposed to different lubricants.

[Graphic: Influence of Lubricant]

Figure 1: Kinetic friction coefficient curve for a paper-based friction material in gear oil

 
Figure 2: Dynamic friction coefficient curve of the same material in hydraulic oil

 
Interpretation: The above chart clearly shows that the same material behaves very differently in gear oil and hydraulic fluid. Furthermore, various additives added to lubricating oils (such as dispersants and anti-wear agents) can interact complexly with the material surface, further affecting its friction properties. Therefore, choosing the right oil for paper-based friction materials is the first step in achieving optimal performance.

Factor 2: The Art of Density Balancing

Density is a trump card for paper-based friction materials. It is directly related to the material's porosity, leading to a delicate balancing act in terms of performance.

High density (low porosity) means a denser material, resulting in better strength and thermal conductivity, lower wear rate, and longer life. However, the downside is reduced oil storage capacity, which can lead to a lower coefficient of friction and compromise power transmission.

Low density (high porosity) means the material is more porous, resulting in greater oil storage capacity and a higher coefficient of friction, which can provide greater braking force or transmit torque. However, the downside is reduced mechanical strength and wear resistance, shortening service life.

Figure 3: Comparison of the dynamic coefficient of friction for materials of varying densities (Type 2 to Type 6, increasing density)

 
Figure 4: Comparison of wear rates of materials with different densities

 
Interpretation: Figures 3 and 4 vividly illustrate this balancing act. There's no such thing as absolute good or bad, only suitability. When selecting a paper-based friction material, the optimal trade-off between friction coefficient and durability must be determined based on specific application requirements (e.g., high torque versus long life).

Factor 3: Extreme Challenges of Operating Conditions

In addition to oil type and density, actual operating conditions, such as surface pressure, sliding speed, and oil temperature, pose extreme challenges to paper-based friction materials. These factors directly affect the temperature of the friction interface, the thickness and stability of the oil film, and thus dynamically alter the coefficient of friction.

Therefore, please remember: the coefficient of friction of a particular paper-based friction material is not a fixed value, but rather a performance range determined through extensive and repeated testing under specific operating conditions.

Broad Applications: Injecting a Powerful "Heart" into Machinery

Thanks to its excellent overall performance and customizability, Carlisle Brake & Friction's paper-based friction materials have been successfully applied to the core components of various heavy-duty machinery, becoming their powerful and reliable "heart."

We understand that different machines and applications require significantly different friction materials. For example:

• Service brakes for construction machinery (such as excavators and loaders) require materials that provide a stable, powerful braking force under high loads to ensure safety.
• Powershift transmissions for agricultural machinery (such as tractors) require materials that provide smooth engagement and excellent heat resistance to handle frequent shifting.
• Clutches for industrial machinery require materials that respond quickly and have a long lifespan to ensure continuous and efficient operation of production lines.

To this end, Carlisle Brake & Friction has developed a series of special paper-based friction materials for different application scenarios, providing each customer with the most suitable and reliable solution.

Continuous Innovation, Driving the Future

Technological advancement is endless. To meet increasingly demanding application requirements and broaden market prospects, Carlisle Brake & Friction remains at the forefront of innovation.

We are not only continuously optimizing the formulation and processing of paper-based friction materials to push their performance limits, but are also actively exploring next-generation wet friction materials with even higher performance. These R&D efforts have made significant progress, aiming to provide global customers with more diverse and advanced options, driving the infinite possibilities of future machinery.

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