Unravelling Polymers

The Definitive Blog on Polymers by Poly Fluoro Ltd.

PTFE in Brake Cables

The use of PTFE (Teflon) tubes extends across a variety of industries due to the exceptional properties of the material. PTFE is able to withstand high temperatures, resist corrosive chemicals, is electrically insulative, and has the lowest friction coefficient among known solid materials. PTFE tubes are made via a special process known as paste extrusion. As the manufacturing process has evolved, so too have the applications into which PTFE tubes are invaluable.

One significant application of PTFE tubes is in the manufacturing of brake cables. Brake cables are a critical component of a vehicle's braking system, and PTFE tubes play a vital role in ensuring their efficiency and durability. Around the world, PTFE is a preferred material of choice for brake cables. In India, cables with rubber cores are still largely used. However, a recent government directive has made it mandatory for PTFE brake cables for two-wheelers. The result has been a significant jump in volumes and a considerable interest in PTFE tubes.

Brake cables are a type of control cable that transmits the force from the brake pedal to the brake callipers or drums. The cable consists of a wire core and an outer casing made of metal or plastic. The wire core is responsible for transferring the force, while the outer casing provides protection and guidance. However, the friction between the wire core and the outer casing can cause significant wear and tear, resulting in reduced efficiency and increased maintenance cost. 

The typical construct of a PTFE brake cable involves a PTFE tube core, with a braided stainless steel sheath around it, and a nylon (usually PA11) outer sheath. The PTFE tubes are used as a liner inside the outer casing of the brake cable. The PTFE tube acts as a lubricant between the wire core and the outer casing, reducing the friction and wear. Moreover, the PTFE tube's low friction coefficient ensures that the brake cable operates smoothly, providing a more responsive and consistent braking performance. This feature is particularly crucial for high-performance vehicles that demand quick and precise braking.

Another significant advantage of using PTFE tubes in brake cables is their resistance to high temperatures. The brake system generates a significant amount of heat during operation, which can cause the outer casing of the cable to expand and contract. This expansion and contraction can lead to the cable's failure or reduced efficiency, resulting in brake failure. PTFE tubes can withstand high temperatures and prevent the outer casing from expanding and contracting, ensuring that the cable operates at peak efficiency even under extreme conditions.

PTFE tubes also offer excellent chemical resistance, making them ideal for use in harsh environments. Brake fluids contain various chemicals that can corrode the metal or plastic outer casing of the cable, reducing its lifespan and effectiveness. However, PTFE tubes are highly resistant to chemicals, ensuring that the brake cable remains functional and efficient for an extended period.

In addition to their functional benefits, PTFE tubes offer several advantages from a manufacturing perspective. The PTFE tubes can be extruded in long lengths, reducing the need for joints and connections, which can be a source of weakness and failure. The extruded PTFE tube can also be cut to the desired length and inserted into the outer casing, simplifying the manufacturing process and reducing production costs. The PTFE tube's flexibility also allows it to be easily formed to fit different cable configurations, making it suitable for use in a variety of vehicles and applications.

PTFE tubes in brake cables have a significant impact on vehicle safety. Brake failure is a leading cause of accidents, and the use of PTFE tubes can help prevent brake failure due to wear and tear, high temperatures, or chemical corrosion. The smooth operation and consistent performance of the brake system ensure that the driver can stop the vehicle quickly and safely, reducing the risk of accidents and injuries.

In conclusion, PTFE tubes are an essential component of high-end brake cables, providing significant benefits in terms of efficiency, durability, and safety. As safety standards become more stringent in India, it is likely that we would see an additional explosion in demand from the four-wheeler segment.

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