Spring Energized Teflon Seals
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Inside PEEK Bearing Materials: High Load Capacity, Low Wear

Engineers are replacing metal bearings too often or are dealing with corrosion, weight, or lubrication failures. PEEK is a high-performance polymer alternative that is changing bearing design. In this article, we look at what PEEK is, why it performs well in many bearing applications, and where it genuinely makes sense to use it.

What Is PEEK and Why Does It Matter for Bearings?

PEEK (Polyether ether ketone) is a semi-crystalline thermoplastic that has proven an excellent solution to many bearing problems. It offers a high strength-to-weight ratio, excellent chemical resistance, a low coefficient of friction, and thermal stability up to 250°C continuous. This combination of properties leads to effective bearing performance, offering PEEK an advantage over both metal and many standard polymer solutions. 

High Load Capacity

The standard performance-bearing metric is the PV rating (pressure × velocity). If we look at the PV ratings of commonly used polymer bearing materials, we see that PTFE is severely limited despite its low friction, and nylon and acetal do not do much better. Unfilled PEEK has the best PV ratio, and when filled with carbon fiber, it has a significantly higher PV rating than other engineering polymers. This alone is an excellent reason to consider using PEEK in bearing applications. And note that filled PEEK grades are typically the main choice for demanding applications, while unfilled PEEK is more commonly used where chemical purity or machineability is the priority.

Low Wear Performance

One of the most interesting features of PEEK as a bearing material is its wear resistance, which is critical for many applications. PEEK’s molecular structure resists abrasion under dynamic loading, and it offers excellent performance in dry-running applications because it is self-lubricating, offering an excellent option when lubricants are discouraged or prohibited. Bearing-grade PEEK filled with carbon or graphite further enhances wear performance by significantly reducing wear rates. The low wear performance of PEEK bearings also leads to reduced downtime and longer maintenance intervals. 

Where PEEK Bearings Make Sense

PEEK has excellent properties, but they are not an ideal fit for all bearing applications. PEEK bearings are commonly used for applications such as the following:

  • Medical devices and surgical equipment, where biocompatibility and sterilization resistance prove critical
  • Food and beverage processing, where the self-lubricating property reduces contamination risks
  • Aerospace and defense, where the high strength-to-weight ratio leads to weight savings, reduced energy requirements, and SWaP-friendly designs
  • Chemical processing, where resistance to acids, solvents, and aggressive media exposure is necessary
  • Semiconductor and cleanroom environments, where PEEK exhibits no outgassing 

There are areas where PEEK is not recommended, however. It should not be used in ultra-high load static applications, where steel still dominates. In addition, it’s not well-suited to very high-temperature environments, which are likely beyond PEEK’s thermal ceiling. Finally, PEEK is not a good option for budget-sensitive, low-performance applications where cheaper plastics work well.

Conclusion

PEEK bearings are not a universal replacement for other materials, but rather a viable option for demanding operating environments where their unique properties justify the cost. If you are looking for a sealing solution that sounds like a great application for PEEK, contact the sealing experts here at Advanced EMC and put their knowledge to work for you.

An example of a subsea AUV
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Polymer Bearings for Subsea Robotics: Surviving Pressure, Saltwater, and Zero-Maintenance Windows

The ocean floor remains one of the most unforgiving environments on Earth. Remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) descend thousands of meters to inspect pipelines, support offshore drilling, and conduct scientific surveys. And these ROVS do all of this in conditions that would destroy conventional mechanical components within hours, including bearings. For engineers designing subsea robotic systems, the question is never whether the environment will push the hardware to its limits. The question is whether the hardware is ready for it.

Bearings are among the most critical and vulnerable components in a subsea robot’s drivetrain, joint assemblies, and thruster systems. Make the wrong design choice here, and the entire mission fails. Make the right design choice, and you have a system that can run reliably at depth for extended deployments without ever surfacing for a service interval. Polymer bearings for subsea robotics are emerging as the answer for engineers who are finding that conventional metal bearings simply cannot provide the performance needed in the harsh environment beneath the ocean.

Pressure, Saltwater, and Maintenance-Free Operation

Subsea robotics engineers, whether they are designing robots for inspecting oil and gas pipelines or monitoring fish farms, face three specific challenges that conventional bearing materials are not designed to handle simultaneously: hydrostatic pressure, saltwater corrosion, and lubrication.

Hydrostatic pressure increases by roughly one atmosphere for every 10 meters (~32.8 ft) of depth. At 3,000 meters (~9840 ft), which is a routine working depth for deepwater inspection ROVs, the pressure exceeds 300 atmospheres. Metal bearings rely heavily on lubrication films and tight tolerances that can easily be compromised under such loads. Pressure-induced deformation, lubricant displacement, and housing distortion can all cause premature failure.

Saltwater corrosion is another relentless issue that must be addressed for successful bearing performance. Corrosion degrades surface finish, tightens clearances, and eventually seizes rotating assemblies entirely. Marine environments expose bearing surfaces to chloride ions, dissolved oxygen, and biological fouling. Steel bearings corrode; bronze bearings can undergo dezincification; and even stainless alloys remain vulnerable to crevice corrosion in low-oxygen zones.

Zero-maintenance windows may be the most operationally demanding constraint of all. A bearing on an offshore ROV working a deepwater site cannot be pulled, inspected, relubricated, or replaced on a daily basis. Many deployments run for weeks or months between topside recovery. Polymer bearings, such as those made from PEEK or PTFE composites, eliminate the need for periodic lubrication or adjustments, reducing operational costs and downtime, and ensuring continuous mission success because they are self-lubricating.

Polymer Bearings: Material Solutions for Subsea Demands

Bearing-grade polymer materials address all three of these challenges — pressure, saltwater, and maintenance-free operation — often simultaneously. Several proven engineering polymers stand out as solutions that can inspire confidence in subsea robotic applications.

PEEK (Polyether ether ketone) is the workhorse of high-performance polymer bearings in subsea use. It maintains exceptional dimensional stability even under hydrostatic loading, exhibits near-zero water absorption, and resists saltwater, hydraulic fluids, and most chemicals commonly encountered in offshore environments. Furthermore, PEEK bearings operate without external lubrication, drawing instead on the material’s inherently low friction coefficient. For ROV thruster assemblies and joint pivots, PEEK offers a compressive strength that approaches or exceeds many metal alloys while eliminating corrosion.

Filled PTFE successfully extends the lubrication-free advantage further. Unfilled PTFE is too soft for structural bearing applications, but glass-filled, carbon-filled, or bronze-filled PTFE delivers self-lubricating performance with meaningful load capacity and low friction. In slow-rotation or oscillating applications, such as the articulating arms of an inspection ROV, field PTfE bearings provide a smooth, stick-slip-free motion with no maintenance requirement and complete resistance to saltwater attack.

UHMWPE (Ultra-High Molecular Weight Polyethylene) brings outstanding impact resistance and surface toughness to applications where debris ingestion is a risk. Its extremely low coefficient of friction, combined with high chemical resistance and excellent fatigue life in wet environments, makes it well-suited for guide bearings and bushing applications in subsea manipulators and cable management systems.

Finally, Torlon (PAI, Polyamide-imide) is ideal for harsh, high-temperature, and high-load bearing applications where even PEEK approaches its limits. With excellent creep resistance and impressive compressive strength, Torlon-based bearings perform well in compact, high-load joint designs where space constraints are tight, and operating cycles are demanding.

Building Reliability Into Every Depth

The common thread across all of these materials is simple: each one removes a failure mode that metal bearings experience in the subsea environment. No corrosion, no lubrication intervals, dimensional stability under pressure, and compatibility with the full range of subsea fluids and cleaning agents are critical properties that high-performance polymers such as PEEK, filled PTFE, UHMWPE, and Torlon possess. 

For operators running extended deepwater missions, polymer bearings are not merely an alternative to metal bearings; they are the more reliable choice. Lower system weight, reduced drag on thruster assemblies, and the elimination of corrosion-driven maintenance costs all contribute to a lower total cost of ownership over the working life of AUVs and ROVs.

Ready to specify the right bearing material for your subsea robotic application? The bearing experts at Advanced EMC have strong expertise in bearing-grade polymers for even the most demanding marine and offshore environments. Contact Advanced EMC today to discuss your project requirements and get material recommendations backed by real engineering experience.