Advancements and Market Dynamics of Filament Wound Bearings in the Engineered Composite Materials Industry

Published on July 9, 2024

Developed in the mid-20th century, filament winding makes composite structures by winding reinforced fibers impregnated with resin around a mandrel or other similar rotating implement. These fibers can be pre-impregnated or added just before winding, though resin can instead be adjoined after the winding process. Once the resin cures, the impregnated filament can be removed from the mandrel, after which finishing treatments may be applied. Originally used in rocket motor cases for the aerospace industry, the applications for filament winding have since expanded.

According to a market research future report, the market for polymer bearings that includes filament wound bearings is set to reach $14.1 billion globally by 2030, with a projected compound annual growth rate of 4.78 percent. The filament winding process has been used to make filament wound bearings for over three decades, with applications expanding into defense, marine, transportation, and many other sectors. Innovations in automation and robotic technology have also increased the use of composites, enabling manufacturers to utilize every more complex shape for filament wound bearings.

What Are Filament Wound Bearings?

Filament wound bearings are composite bearings with filaments wound up into a helix arrangement, which augments the bearing wall’s strength. Interwoven with glass filaments, liners made from a combination of materials like meta-phenyleneisophthalamide (Nomex® meta-aramid), polyethylene terephthalate (PET or polyester) and polytetrafluoroethylene (PTFE) provide a reinforced structure. With multiple layers, filament wound bearings last longer and are generally more reliable, often incorporated into products to ensure no or very low maintenance. 

Their high-strength design allows for thinner bearing walls that can reduce both the size and weight of assemblies, a plus for aerospace and other applications. The self-lubricating properties and seamless concentric construction of filament wound bearings give them an exceptionally low friction coefficient, allowing them to bear higher loads and making them more durable. This self-lubricating property comes from a film of PTFE that transfers from the bearing’s bore to the shaft.

Properties of filament wound bearings include: 

  • Handling high loads and wide temperature ranges.
  • Having a low friction coefficient.
  • Lowering maintenance expenses.
  • Meeting ROHS requirements.
  • Not corroding or wearing easily.
  • Resisting chemicals and contamination well.
  • Tolerating wear to edges.
  • Withstanding misalignment, shock loads, and vibrations.

While lubricants aren’t required, additional lubrication will extend filament wound bearings’ lifespan, protecting them against contaminants. Designed for safety, filament wound bearings can withstand extreme conditions while being interchangeable with other materials.

Applications for Filament Wound Bearings 

While still widely used in the aerospace industry, filament wound bearings are also used for agriculture, construction, food processing, forestry, material handling and processing, medical, mining, railroad, recycling, waste management, and other industrial machinery. New bearing types continue to be developed. These include bearings from about 8 mm (.314 inch) to 60 cm (23.622 inches) and those featuring non-circular bores, low friction surfaces, level sliding surfaces, integral flanges, and high compression strength. Many innovations regarding materials and forms allow them to be used in applications where metallic bearings were previously used.

Filament wound bearings can be used for items that include: 

  • Aerial lifts
  • Boom loaders
  • Clutches for ATVs and snowmobiles
  • Conveyors
  • Cranes
  • Excavators
  • Hoists
  • Hydraulic cylinder bushings
  • Industrial equipment
  • Loading shovels
  • Water and wind turbines

Many of these applications benefit from the higher performance of filament wound bearings. Combined with their lower upfront and maintenance costs and the weight savings they provide, these bearings can be used under harsh operating conditions. The elimination of lubricants also makes them desirable for their diminished impact on the environment.

Beneficial Qualities of Filament Wound Bearings

While they’re considered one of the strongest composite bearings, the versatility of filament wound bearings makes them a good replacement for bronze and other materials in many applications. They work particularly well when used for applications that involve back-and-forth movement at varying frequencies. These bearings can additionally be used for linear and rotary movement without requiring lubrication. Filament wound bearings also offer beneficial qualities like corrosion resistance, elasticity, longer lifespan, self-lubrication, and shock absorption.

Corrosion Resistance

Their multilayer construction makes filament wound bearings resistant to chemical-related, fretting, and galvanic corrosion. As corrosion is a prime cause of bearing failure, these bearings last longer.  


Though not as elastic as softer plastics, the material from which filament wound bearings is made is much less rigid than metal. This allows these bearings to support heavy loads and endure when shafts become misaligned without causing undue stress to bearings. 

Longer Lifespan

Able to resist abrasion as well as corrosion, filament wound bearings can easily last half a million cycles without any additional lubrication. However, improving the surface and Rockwell hardness rating can extend bearing lifespans even further. However, tests have shown that bearing lifespans can more than double to over a million cycles with a Rockwell hardness score of 55 and RMS (root mean square) finish of 8, essentially a mirror finish. To put the filament wound bearings’ hardness in perspective, the type of stainless steel used as standard bearing material – 440C stainless steel – has a Rockwell hardness rating of 60, and that’s only after heat treatment.


Because they’re self-lubricating, filament wound bearings can also run without lubrication. This saves not only on the cost of the actual lubricants, but also on the manual labor involved. 

Shock Absorption

Because of the unique helix configuration, filament wound bearings can withstand vibrations, shock, and other demanding conditions without failing. These bearings’ thin, filament-impregnated walls can more easily withstand compression, recovering easily after impacts that often occur when machinery operates nonstop.

Innovations in Filament Wound Bearings

Research has been ongoing since the 1990s regarding the feasibility of complex geometries for composite bearings, including filament-wound ones. Bearings made from composites are increasingly fabricated using automated techniques, including robotic systems for winding filament. Wound bearings are made using automated systems that feed and deposit resin-impregnated fibers along stress lines within parts with complex geometries. This method is called robotic filament winding (RFW), with industrial robots replacing manual labor. RFW systems are the best way for manufacturers to control processes, guarantee consistency, and truncate fabrication times.

Innovations are also being made with curing composites used for filament wound bearings. For example, nadic methyl anhydride (NMA) has been proven to be particularly advantageous for curing epoxy resins, the final part of making filament wound bearings. Their ability to perform well in high temperatures and superior electrical properties make epoxies cured with NMA perfect for electronic circuits and other components.

Filament Wound Bearings & the Composite Bearing Market 

As noted earlier, the composite bearing market is set to grow respectfully over the next several years. This is largely due to the advantages composites present over metals or alloys, which are being methodically replaced by polymers like PTFE, PET, polyether-ether-ketone (PEEK), polyoxymethylene (POM), and polyamides (nylons) for bearings. These bearings have become popular for difficult applications, leading to the rapid wear to bearings made from conventional materials. As composite materials are often only a fraction of the weight of steel, they lose less momentum from friction and need less energy to set into motion.

Though they don’t require lubrication, filament wound bearings, when lubricated, will run with almost no noise, while they can also handle shock loads better. High-performance polymers like PEEK or polyamides used in composite bearings can manage heavy leads while functioning within temperatures of over 300°C (572°F). However, because of the high costs of these polymers, filament wound and other types of composite bearings tend to be used where price is less of a factor, like aerospace or medical applications.

Filament Winding by Spaulding Composites 

Spaulding Composites Inc. manufactures both components and materials made from engineered thermoset composites. We use filament winding to produce complex and lightweight composite structures for specific applications, seeking not only to meet but exceed the requirements of our customers worldwide. To learn more about our products and services, contact the composite experts at Spaulding.