Material Matters — Choosing the Right Seal Material for Aerospace and Beyond

In aerospace applications, failure is not an option. From high-altitude pressure swings to extreme temperatures and aggressive fluids, seals must maintain performance in some of the harshest operating conditions imaginable. And while design, geometry, and installation all play critical roles, one factor often determines success or failure before a seal is ever installed: the material.

In This Blog:

• Seal Material Selection in Aerospace

• Why Material Choice Determines Performance

• PTFE: The Aerospace Workhorse

• Filled PTFE Compounds 

• High-Performance Elastomers in Aerospace

• Material Selection Beyond Aerospace
  

• How Ergoseal Supports Material Selection

At Ergoseal, we work closely with aerospace OEMs to engineer sealing solutions that meet not only demanding physical requirements but also strict standards for safety, traceability, and consistency. A key part of that process is material selection.

Below, we break down the materials most commonly used in aerospace sealing applications — and how to choose the right one for your performance and compliance needs.

PTFE: The Aerospace Workhorse

Polytetrafluoroethylene (PTFE) is widely used in aerospace seals for good reason. It offers a rare combination of:

• Excellent chemical resistance
• Broad temperature range (from cryogenic to over 500°F)
• Low friction and wear
• Compatibility with a wide range of aerospace fluids and gases

In dynamic sealing environments, PTFE minimizes stick-slip behavior and maintains integrity under extreme cycling. Its natural lubricity also reduces energy loss due to friction, making it a smart choice for efficiency-critical systems like environmental control units (ECUs), actuators, and pumps.

According to Gerald Strenk, Global PTFE Product Manager at Ergoseal, a common mistake is overgeneralizing:

“Even among seasoned aerospace engineers, a surprisingly common mistake is treating ‘PTFE’ as if it’s a single, predictable material rather than a family of behaviors that shift dramatically with load, temperature, and time. Another is not aligning the right AMS spec — like AMS 3656 versus filled variants — with actual load and temperature requirement,” he says.

Filled PTFE: Tailored for the Mission

While virgin PTFE is versatile, aerospace applications often demand enhanced mechanical strength, wear resistance, or dimensional stability. That’s where filled PTFE compounds come in.

Fillers are added to PTFE to overcome some of its limitations—particularly creep (cold flow), low wear resistance, and limited load-bearing capacity. By reinforcing the base material, fillers help create a more robust and application-specific sealing solution.

Common fillers include:

• Glass fibers: Improve compressive strength and reduce creep
• Carbon: Enhances wear and thermal conductivity
• Bronze: Adds dimensional stability and load-bearing capacity
• Molybdenum disulfide (MoS2): Reduces friction further

“Material selection is application-specific, and there are many blends with fillers and even virgin PTFE can be chosen,” Strenk explains. “Because Aerospace is demanding, there is a high demand for materials that have very good wear properties. A few common materials for high wear properties in Aerospace I would recommend would be a glass moly filled PTFE or a carbon fiber filled PTFE. For other bearing types and high-load applications, bronze-filled can be used. Virgin PTFE can also be used where low friction and high wear are not common.”

At Ergoseal, we work with aerospace partners to develop custom PTFE blends optimized for specific use cases like high-speed rotating shafts or chemically aggressive environments. These formulations are often validated through our in-house testing to ensure compliance with AS9100D requirements and customer specs.

High-Performance Elastomers

While PTFE dominates in many aerospace sealing scenarios, elastomers remain necessary for certain static and dynamic seals where flexibility, resilience, and ease of installation matter.

Popular aerospace elastomers include:

• Fluorocarbon (FKM/Viton®): Excellent for high-temp and fuel-resistant applications
• Fluorosilicone: Combines low-temperature performance with fuel resistance
• EPDM: Ideal for water systems and ozone resistance

Choosing the right elastomer depends heavily on the media, temperature extremes, and potential for long dwell times or infrequent cycling.

According to Strenk, elastomers are preferred in cases with low-pressure, slow motion, or where systems can’t tolerate creep or relaxation. It’s also recommended to lean toward elastomers when there’s misalignment, debris, rapid pressure cycling, or risk of installation damage. In some cases, pairing a PTFE element with an elastomer creates an ideal hybrid solution.

Material Selection Beyond Aerospace

While this discussion primarily focuses on aerospace, the principles of material selection are applicable across various industries, including power generation, medical devices, chemical processing, and others. Many of these environments share challenges with aerospace, including pressure extremes, aggressive fluids, and tight performance margins.

In all cases, choosing the wrong material can result in premature wear, energy inefficiency, or system failure.

How Ergoseal Helps

Choosing the right material is rarely straightforward. That’s why we partner early in the design process to:

• Evaluate application conditions (temp, pressure, media)
• Recommend materials based on performance data and prior use cases
• Prototype and test seals in our in-house lab
• Support traceability and documentation to meet aerospace and defense requirements

With AS9100D certification and a deep bench of engineering expertise, we help ensure your seal materials are as reliable as the systems they protect.

Let’s find the right material for your mission. Get in touch with us today!