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PPS Bushings

There are a variety of bushings in your typical off-road bicycle, from the rear derailleurs to free wheeling hubs.  These types of bikes require bushings that can handle a demanding, intense, unpredictable environment.  There are a variety of materials to choose from, and in this article we are going to look at carbon fiber reinforced PPS material..

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Get more information on Advanced Polymer Bushings from the design Engineer’s choice Advanced EMC Technologies Blog:


 

Background

PPS stands for polyphenylene sulfide, sometimes referred to by its tradename Ryton.  It belongs to a subdivision of polymers known as sulfide polymers.  It was first developed in the 1880s, but its potential as an engineering polymer wouldn’t be recognized for another 60 years.  In the 1970s an efficient technique for injection molding PPS was developed, and from there it began to advance to the forefront of engineering plastics.  PPS bearings eventually became a popular alternative to metal and ceramic bearings.  Let’s take a look at why.

 

Temperature and Chemical Resistance

PPS offers excellent temperature resistance, able to perform in in temperatures up to almost 400°F long term, and handle short term temperature spikes of up to 500°F.  Its corrosion resistance makes it ideal for aggressive environments.  In fact, its’s chemical resistance is second only to PTFE.  That means PPS bike bearings can handle exposure to corrosive environments, and temperatures won’t be an issue at all.

 

Manufacturing

Critical bearings need to be precision molded with tight tolerances.  PPS can be injection molded, machined, compression molded, or extruded to exacting tolerances with high reproducibility.

 

Dimensional Stability

PPS retains its dimensional stability in the presence of high temperatures, as well as high mechanical loadings. It offers almost no moisture absorption, and exhibits very little creep.  This is key for a critical bearing that may be exposed to intense loadings and wet environments.

 

Reinforcement

PPS can be reinforced with carbon fiber to improve its strength and wear resistance, and provide internal lubrication.  Its tensile strength is 17 ksi with a tensile modulus of 1.8×106 psi, and its flexural strength is 23 ksi with a flexural modulus of 1.7×106 psi.  This is an excellent option for its use in bearings for demanding environments like those faced by off-road bikes.

 


Reinforced PSS Material for Bushings:

Reinforced PPS is lightweight but durable, self-lubricating, and wear resistant. In addition, PPS is offers excellent flame retardant properties. Finally, it’s considered a valid alternative to PEEK (polyetheretherketone) for service at lower temperatures, lower costs, and comparable coefficent of friction.  When selecting bearings for an off-road bike, don’t forget to have reinforced PPS in your list of potential materials.

 

For more information….download the bearing materials chart from Advanced EMC Technologies.

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