Understanding PTFE Fillers in Material Selection for Bearings

PTFE (Polytetrafluoroethylene) is one of the most widely used fluoropolymers in the world, known for its exceptional chemical resistance, high-temperature performance, and low friction properties. However, in most bearing applications, unfilled PTFE is rarely used on its own.

Instead, PTFE materials, such as Rulon®, are modified with fillers to optimize material selection for specific application requirements. These fillers enhance wear resistance, improve load capacity, reduce creep, and tailor thermal and tribological performance.

At TriStar Plastics, material selection for PTFE-based bearings is not about choosing a base polymer; it’s about selecting the right filler system for the application.

In this guide, we explore how common PTFE fillers influence performance and how they impact engineering decisions in bearing design.

Why PTFE Fillers Matter in Material Selection

Unfilled PTFE offers low friction but it also has limitations, including:

• Higher creep under load

• Lower wear resistance in dynamic applications

• Reduced dimensional stability

Fillers are introduced to overcome these limitations and align material properties with real-world application demands.

Effective material selection using filled PTFE allows engineers to:

• Improve wear resistance and service life

• Increase load-carrying capacity

• Enhance thermal conductivity

• Control thermal expansion

• Optimize friction behavior

This is why PTFE filler selection is a critical step in bearing material selection, not just a formulation detail.

Common PTFE Fillers and Their Role in Material Selection

Glass-Filled PTFE

Glass is one of the most common fillers used with PTFE for applications requiring improved structural stability.

Material selection benefits:

• Reduced coefficient of thermal expansion

• Improved compressive strength

• Better dimensional stability under load

• Lower creep and cold flow

Best suited for:

• Bearings and seals requiring tight tolerances

• Electrical applications needing dielectric stability

Carbon-Filled PTFE

Carbon enhances PTFE for applications involving higher loads and thermal demands.

Material selection benefits:

• Increased thermal conductivity

• Improved wear resistance

• Reduced deformation under load

• Enhanced anti-extrusion properties

Best suited for:

• Dynamic seals and bearing surfaces

• Applications with continuous motion and load

Graphite-Filled PTFE

Graphite is commonly used to enhance lubrication performance and friction control.

Material selection benefits:

• Lower coefficient of friction

• Improved wear resistance

• Enhanced transfer film formation

• Superior self-lubricating behavior

Best suited for:

• Bearings, seals, and piston rings

• Applications requiring long life and low friction

Molybdenum Disulfide (MoS2)-Filled PTFE

MoS₂ is a solid lubricant used in high-load, high-pressure environments.

Material selection benefits:

• Enhanced wear resistance under pressure

• Improved dry lubrication performance

• Increased load-bearing capability

Often combined with other fillers (glass or bronze) to balance properties.

Best suited for:

• Slide bearings

• Thrust washers

• Mechanical seals

Bronze-Filled PTFE

Bronze significantly improves load capacity and thermal performance.

Material selection benefits:

• Increased thermal conductivity

• Reduced creep

• Improved wear resistance

Best suited for:

• High-load dynamic applications

• Bearings and seal rings exposed to heat and pressure

Mineral-Filled PTFE

Minerals are often used when regulatory compliance and chemical resistance are required.

Material selection benefits:

• Improved wear and load resistance

• Excellent chemical resistance

• FDA-compliant options available

Often blended with other fillers for application-specific performance.

Polyester-Filled PTFE

Polyester enhances PTFE for high-temperature and load-bearing applications.

Material selection benefits:

• Improved heat resistance (up to ~500°F range)

• Better wear resistance

• Increased dimensional stability

Best suited for:

• High-temperature seals and bearings

Polyimide-Filled PTFE

Polyimide is used in PTFE for extreme performance environments.

Material selection benefits:

• Increased compressive and flexural strength

• Exceptional wear resistance

• High thermal stability

• Broad chemical resistance

Best suited for:

• Aerospace and high-performance industrial components

• Bearings, seals, and valve components

Expert Note from TriStar: Selecting a PTFE material is not about choosing a single filler; it’s about balancing multiple properties for the application. Our engineers evaluate load, speed, temperature, environment, and mating surfaces to recommend the right combination of fillers that will deliver consistent performance over time.

Material Selection Is About Formulation As Well As Fillers

In real-world applications, PTFE materials are rarely defined by a single filler. Instead, they are engineered through:

• Combinations of fillers

• Specific filler percentages

• Processing methods

• Additives and pigments

This creates a wide spectrum of material options, allowing TriStar to tailor bearing performance for:

• Wear life

• Friction control

• Load handling

• Environmental resistance

Material selection is ultimately about matching this formulation to the application—not choosing from a generic category.

The Bottom Line: PTFE Fillers Enable Precision Material Selection

The incorporation of fillers transforms PTFE from a general-purpose low-friction material into a highly engineered bearing solution.

With the right material selection strategy, PTFE-based materials can:

• Replace greased metal bearings

• Extend service life

• Reduce maintenance

• Improve system reliability

We Can Help

If you’re evaluating PTFE materials for:

•  Bearings or bushings

• Seals or wear components

• High-load or high-temperature environments

TriStar’s engineering team can help you select the optimal PTFE formulation based on your application requirements.

Ask our engineering experts for a material recommendation or design consultation.