I. Why You Might Need PTFE-Coated O-Rings

If you have encountered issues such as high assembly resistance, O-ring sticking, susceptibility to chemical corrosion, or abnormal wear in dynamic mechanisms when designing or selecting rubber O-rings, you have likely come across or are already using PTFE coated O-rings.

In industrial fields such as automotive, industrial equipment, hydraulic systems, and refrigeration systems, PTFE-coated O-rings can provide the following advantages without compromising the sealing performance of the rubber O-ring itself:

• Lower assembly force (friction coefficient ranging from 0.05 to 0.15)
• Clean, non-sticking surface
• Enhanced wear resistance under dynamic conditions
• Improved chemical resistance
• Better thermal stability
• Color modification for easy identification and error prevention
• Polytetrafluoroethylene (PTFE), commonly known as Teflon, is a solid polymer that can be used continuously at temperatures up to 260°C, with a maximum operating temperature of 290–300°C. It exhibits an extremely low friction coefficient, good wear resistance, and excellent chemical stability.

II. What Is PTFE Coating?

Polytetrafluoroethylene, commonly referred to as “Teflon,” is a fluoropolymer. The stability of its carbon‑fluorine molecular bonds gives PTFE exceptional chemical inertness and thermal stability.

Since PTFE does not naturally adhere well to substrates, it is typically formulated into a suspension with binders (such as polyamide-imide), dispersants, and solvents, and then applied as a dispersed coating on rubber product surfaces.

PTFE-coated O-rings remain fundamentally rubber O-rings. The elasticity and sealing performance still rely on familiar rubber materials such as HNBR, FKM, EPDM, FVMQ, or silicone.
The PTFE coating is merely a functional layer on the surface, which does not alter the cross-sectional dimensions or groove fit of the O-ring.

III. How Is the PTFE Coating Process Implemented?

1. Surface Pretreatment
   Before coating, rubber O-rings must be cleaned to remove release agents and residues.
   This step ensures that the coating does not delaminate or fail locally during use.
2. Coating Application
   Electrostatic spraying is employed: Under an electric field, PTFE particles are charged and directionally adsorbed onto the substrate, with a typical coating thickness of 3–10 micrometers.

3. Curing and Inspection
The coating is cured under controlled temperatures to allow the PTFE resin to melt, level, and form a stable three-dimensional network.
Key control parameters include the heating rate (≤5°C/min) and holding time (20–40 minutes) to prevent coating cracking due to thermal stress.
The entire process does not affect the elasticity, compression set, or sealing capability of the rubber core.

Curing in oven

100% visual inspection

V. Engineering Application Examples

• Automotive Fuel & Fluid Systems
  PTFE coating on hydrogen fuel cell bipolar plate sealing grooves reduces contact resistance while withstanding cold-start shocks. Coating sealing rings in various automotive pipeline connectors reduces assembly resistance during production and insertion/extraction forces during application.
• Hydraulic and Pneumatic Systems
• Air Conditioning & Refrigeration Systems
• Chemical Processing Equipment
  In ultra-high-temperature, ultra-high-pressure hydrogen environments, PTFE coating on hydrogenation reactor flange sealing surfaces extends sealing life and reduces maintenance costs.
• Food & Pharmaceutical Equipment
  PTFE coatings compliant with FDA 21 CFR 177.1550 enable zero-lubricant use in rotary shaft seals of sterile filling equipment, eliminating product contamination risks.
• Valves, Pumps, Connectors, Quick Couplings

VI. What Are PFAS Requirements and Their Impact on PTFE Applications?

PFAS (per- and polyfluoroalkyl substances) are a large group of “persistent chemicals” regulated globally due to their resistance to degradation and potential environmental and health hazards.
All compounds containing perfluorocarbon chains are broadly considered PFAS, so strictly speaking, PTFE falls within this category.

However, most mainstream regulations do not explicitly classify PTFE as a “prohibited PFAS substance” (i.e., PTFE is not currently listed among mandatory banned substances).
In the long term, to comply with PFAS requirements, it is advisable to plan for alternative solutions. Currently, we offer PFAS-free coating options for customers to choose from, such as:

• PTFE coatings without PFAS additives
• PF coatings based on PFPE liquid substrates
• other dry film lubricant, like FUCHS GLEITMO 2345

VII. OBT O-Ring Coating Solutions
We can provide various PTFE coating solutions based on customer needs:

• Spray or immersion application methods
• Different coating thicknesses
• Different PTFE base materials
• Various PTFE coating colors, such as blue, green, white, etc.

PTFE coated o-ring Brown	PTFE coated o-ring Blue	PTFE coated o-ring Red
PTFE coated o-ring Green	PTFE coated o-ring Grey	PTFE coated o-ring Purple

Ultimately, whether coated or not, the core performance of an O-ring still depends on the rubber material itself.

We look forward to contact with you to finalize a suitable rubber material selection and PTFE coating solutions for O-rings.

FAQ