Beyond the Tire: The Unseen Power of Rubber in Modern Automobiles

Current Applications of Rubber in the Automotive Industry

Automotive rubber products are indispensable and crucial components in vehicle parts. Depending on the type of vehicle, each car requires the installation of approximately 100 to 200 different rubber products, totaling around 200 to 500 rubber components. Excluding tires, the amount of rubber material used ranges from 15 to 60 kilograms per vehicle, varying by car model. The cost of rubber products (excluding tires) accounts for about 6% of a car's total cost. The automotive industry utilizes over 1,000 types of non-tire rubber products, with more than 8,000 specifications. According to statistics, the automotive sector consumes over 70% of the world's annual raw rubber supply, with tires accounting for 60% and automotive rubber parts making up the remaining 40%.

High speed, safety, comfort, energy efficiency, and environmental protection are the key goals pursued by modern automobiles. With the advancement of automotive technology, the requirements for automotive rubber products have become increasingly stringent and demanding. Not only are rubber materials with various special properties needed to meet new technical requirements, but they must also exhibit higher physical and mechanical performance, such as aging resistance, high-temperature and low-temperature resistance, resistance to new types of fuels, excellent dynamic fatigue performance, and long service life. In fact, every high-performance feature of modern automobiles relies on the technological progress of rubber products. The performance and quality of automotive rubber components play a critical role in enhancing the overall quality of vehicles. It is worth noting that although rubber products always serve as auxiliary components in various mechanical equipment, they significantly influence the technological advancement and performance of the main systems. Therefore, it can be said that the technological progress and quality level of automotive rubber products largely reflect the overall technical level of vehicles.

The Role of Automotive Rubber Products in Modern Vehicles
Automotive rubber products can be classified into six main categories: tires, sealing products, vibration dampers, belt products, hose products, and other products (such as wipers, mudguards, adhesives, sealants, and interior components).

1. Automotive Tires
Tires are one of the most critical components of a vehicle. They directly contact the road surface and work together with the suspension system to absorb shocks during driving, ensuring a comfortable ride and smooth operation. They also provide excellent adhesion between the wheels and the road, enhancing traction, braking, and overall vehicle performance. Additionally, tires bear the vehicle's weight, making their role increasingly important in modern automobiles.

Most modern automotive tires are primarily made of natural rubber or synthetic rubber. Natural rubber offers superior overall performance compared to synthetic rubber, which is why high-end tires often use it. To achieve the required properties for tire manufacturing, various chemical additives are incorporated into the rubber. One crucial additive is carbon black, which has exceptional adsorption properties. Carbon particles bond strongly with rubber molecules, enhancing hardness, strength, and wear resistance. Since carbon black and rubber are used in roughly equal amounts, automotive tires are essentially a composite material of rubber and carbon black.

2. Sealing Products
A modern passenger car contains over 240 sealing components. Though small, these rubber parts play a vital role, especially in critical sealing applications, where minor deviations can lead to significant issues. Balancing leakage prevention and sealing efficiency remains an eternal challenge in automotive design. Automotive rubber sealing products are generally divided into six categories:

A. Various Types of Sealing Strips – Automotive sealing strips serve decorative and functional purposes, effectively blocking dirt and noise while providing dustproof, waterproof, and soundproof effects. They also absorb vibrations and shocks during driving, improving cleanliness and comfort.
B. Oil Seals – Mainly used for sealing rotating or reciprocating shafts, offering high-speed compatibility, self-sealing properties, and long service life. They are high-precision rubber components.
C. Brake Cups – Used in automotive braking systems, brake fluid transmits pressure to achieve braking in hydraulic brake systems.
D. Dust Covers – Though simple, they require heat resistance, cold resistance, oil resistance, fatigue resistance, ozone aging resistance, and good tensile properties.
E. Brake Diaphragms – Act as diaphragms in brake chambers, transmitting pressure in braking systems.
F. O-Rings – Prevent leakage and protect against environmental contaminants. Used in engines, gearboxes, main shafts, and hydraulic/pneumatic systems to ensure proper operation.

3. Vibration Dampers
Vibration dampers are used in automotive engines, chassis, and other components to reduce vibrations and noise during driving. Compared to other damping products, rubber dampers offer the following advantages:
① Greater design flexibility in shape;
② Six-directional spring-like effects, allowing rotation in X, Y, and Z axes;
③ Suitable damping performance for low to high-frequency applications;
④ Multiple functions, including vibration reduction, shock absorption, and noise isolation;
⑤ Impact stiffness greater than dynamic stiffness, which is greater than static stiffness, reducing shock and dynamic deformation.

4. Belt Products
Belts in automobiles are primarily used to transmit torque, power, and speed, transferring energy from the engine to various systems. They are installed in cooling fans, water pumps, brake compressors, power steering pumps, air conditioning systems, and steering mechanisms. The most common type is the V-belt, which includes wrapped V-belts, raw-edge V-belts, and multi-ribbed V-belts, with raw-edge V-belts being the most widely used. Raw-edge V-belts have no fabric covering on the sides, offering better flexibility, higher friction coefficients, greater load capacity, high-speed capability, excellent heat dissipation, fatigue resistance, and energy efficiency. Commonly used rubber materials include NBR and CR. Timing belts are used in engine valve timing and ignition systems, operating under high-speed, high-power, and high-temperature conditions.

5. Hose Products
Hoses are used in three main areas of a vehicle: chassis, engine, and body. They serve seven systems: fuel delivery, air intake, drivetrain, control, braking, cooling, and heating, providing functions such as fuel supply, air supply, water circulation, and power transmission. Hose varieties include fuel hoses, water hoses, brake hoses, vacuum hoses, air conditioning hoses, radiator hoses, power steering hoses, and branched hoses.

6. Other Products
Besides the above-mentioned rubber products, other key automotive rubber components include brake diaphragms, cups, and dust covers. Future development priorities include:

• Using fluorosilicone rubber and polyester fabric to produce fuel pressure regulator diaphragms for passenger cars;

• Applying chlorinated polyethylene in automotive diaphragm manufacturing;

• Improving weather resistance for dust cover materials;

• Transitioning from chloroprene rubber to thermoplastic polyolefin elastomers (TPO) for constant velocity joint boots, meeting heat, oil, and weather resistance requirements while enabling vehicle lightweighting.

Future Development Directions for Automotive Rubber
As automotive technology advances, the performance requirements for rubber materials are becoming stricter, and the variety of materials is increasing. For example, higher operating temperatures, reduced emissions, lower noise levels, and increased power output are raising engine compartment temperatures, leading to a shift from natural rubber to ethylene propylene diene monomer (EPDM), from nitrile rubber to hydrogenated nitrile rubber (HNBR), acrylic rubber, and fluororubber, and from vulcanized rubber to thermoplastic elastomers (TPE). The development and application of rubber compounding and multi-material integration technologies are continuously improving the performance of automotive rubber products.

Recommendations for Improving Automotive Rubber Technology in China
(1) Government Support, Industry-Academia Collaboration, and Key Technology Research
China is already a major global producer and seller of automobiles but is not yet a leader in automotive technology. The quality of automotive rubber components is one of the most critical factors affecting vehicle quality. Government technology departments should prioritize this issue and take responsibility for addressing it. The government should organize industry experts to focus on key technological breakthroughs. Promoting the "industry-academia-research" model, where universities, research institutes, and enterprises collaborate, can be effective. Provincial or ministerial science and technology departments should organize experts to identify, evaluate, and fund key research projects in automotive rubber materials and technology. Research funding should be jointly provided by the government and enterprises, with selected enterprises and academic institutions conducting the research. After several years of dedicated effort, significant improvements can be expected.

(2) Research and Development of Specialized Raw Materials to Address Supply Shortages
a. Synthetic Rubber Varieties – High-quality EPDM for composite sealing strips and brake diaphragms; fluororubber for high-temperature (above 200°C), high-pressure, and wear-resistant engine oil seals; fluorosilicone rubber, wear-resistant acrylic rubber, hydrogenated carboxylated nitrile rubber, oil-resistant silicone rubber, and low-temperature-resistant acrylic rubber.
b. New Vulcanizing Agents, Additives, and Reinforcement Materials – Developing next-generation environmentally friendly cross-linking agents, accelerators, and additives, as well as high-strength reinforcement materials such as adhesion-enhanced polyester, high-strength glass fiber, and stable aramid fibers.
c. Accelerating High-Precision Product Development Through Industry-Academia Collaboration – Increasing the localization rate of high-end automotive components.