High speed bushings can be found in applications as diverse as agricultural equipment and rollercoasters. When it comes to high speed applications, however, polymer bushings are often underestimated.
In this blog post, we are going to discuss the top four polymer materials for high speed bushings.
Characteristics of High Speed Bushings
When it comes to high speed applications, bushings need low friction, good wear characteristics, and pretty good thermal performance. The four materials discussed in this post bearing grade PEEK, PPS, Torlon, and Polyimide all possess the qualities needed to excel in high speed environments, and are often used as replacement materials for both metal and ceramic bushings.
1. Bearing Grade PEEK
Bearing grade PEEK can handle both high speeds and high pressures. Its maximum operating temperature is around 480°F and it combines excellent chemical resistance with outstanding wear properties. The coefficient of friction of virgin PEEK is 0.4, but that can be reduced to 0.2 through the use of additives. PEEK bushings are an excellent option for replacing metal bearings, and in some instances, they have been found possess 100x better fatigue performance than their metal counterparts. Finally, depending on the thickness of the bushing, PEEK can usually be injection molded.
PPS, sometimes referred to by the trade name Ryton, has excellent wear properties and, with additives such as carbon and graphite, can be used in dry running applications. Its chemical resistance is second only to PTFE and its maximum continuous operating temperature is around 400°F. PPS is often considered a lower-cost alternative to bearing grade PEEK because of the similar temperature range and coefficient of friction.
Torlon is a trade name for a particular grade of PAI (polyamide-imide). It has a continuous service temperature of 500°F, a coefficient of friction as low as .15 with excellent wear properties. Torlon offers excellent impact resistance and compressive strength. It is available in wear resistant grades that can be used in both dry and lubricated environments. Like bearing grade PEEK, Torlon is a popular replacement material for metal bushings and can handle both high speeds and high pressures. In addition, Torlon PAI can be injection molded.
Polyimide, sometimes referred to by the Dupont trade name Vespel, is another outstanding choice for high-speed bushings, with coefficient of frictions as low as .17 unlubricated. They have excellent wear performance, which is key for high speed applications. Like most of the other polymers discussed in this blog post, polyimide offers excellent wear resistance combined with very good chemical and thermal performance. Its maximum operating temperature is on the order of 500°F. As an added bonus, polyimide also works well for noise attenuation. Note that polyimides can be injection molded.
Polymers for High Speed Bushings
When it comes to high speed applications, dont underestimate the performance capabilities of polymers like PEEK, PPS, Torlon, and Polyimide. They have the wear characteristics, low friction, and high operating temperatures needed to meet or even outperform their metal and ceramic counterparts.
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