PTFE seals and composites
Dynamic and precise – choose PTFE seal for optimal performance in extreme conditions
Custom-made PTFE seals (polytetrafluoroethylene) for rotary applications are high-performance sealing solutions designed for demanding dynamic friction. Used in industries such as aerospace, chemical, pharmaceutical, and rotating equipment, these seals are distinguished by their exceptional resistance to extreme temperatures, aggressive chemicals, and wear.
This sealing technology has been a major advancement in improving the reliability of some more critical bearings, such as aircraft engines. PTFE, often reinforced with additives such as graphite or fiberglass, offers a low coefficient of friction, reducing wear and ensuring a reliable seal around rotating shafts, even at high speeds. Their custom design allows them to adapt to complex geometries and specific conditions, ensuring optimal performance in the most demanding environments.
At ELASFOR, we excel in selecting custom profiles and modified PTFEs, designed to precisely meet our customers’ needs. Whether you require a specific dimension, a particular profile, or a material suitable for corrosive fluids or extreme temperatures, our expertise allows us to produce seals in every imaginable configuration. We will work with you to find durable, reliable sealing solutions that are perfectly suited to your equipment.
FKM (Viton) Seals vs. PTFE Seals - When It's Time to Upgrade
A high pressure FKM (viton) solution may not be giving you enough bang for your buck, here are some signs it may be time to upgrade to a PTFE seal:
Thermal Amplitude — Your system is approaching 200 deg.C, must perform during our winters or your temperature varies greatly from one cycle to the next. Your current seal is losing elasticity.
Aggressive chemical environments — Presence of solvents, corrosion, and strong acids. Your current seal is crumbling at the lip or showing signs of swelling.
High Speed or Friction — You are exceeding 20m/s in continuous friction speed or your rod has a mirror finish. Your current seal has a glossy finish (glazing) and the lip is wearing out quickly.
Insufficient FKM seal life — System disassembly time and maintenance costs are high. Your current seal gives you 800-1200 hours, but you’re aiming for 2000+.
High pressure or hydraulic pulsations — The seal lips are deformed, stretched, or simply destroyed (extrusion). On paper, your FKM seal should withstand your pressure, but you suspect that the actual pressure may exceed it.
Energy efficiency or performance requirements — Your advanced system is sensitive to friction. Rolling energy loss must be avoided at all costs.
Be careful, a good analysis never neglects the limitations:
Elasticity
PTFE has a high compression set. This means that to maintain a constant sealing force, it is sometimes necessary to add additional design elements such as a backup spring or increase the sealing surface to correct for rod vibrations or eccentricities.
Surface finish and hardness of the shaft
PTFE lip seals require harder, smoother seating surfaces on the shaft to prevent the seal from digging into it and permanently damaging it while creating a leak.
Installing the seal
These seals must be protected by a retaining ring during transport and storage to maintain the integrity of the PTFE lips, which are often very fragile and tend to open towards the center and lose their original shape. The use of sharp tools or installation on elements without chamfers often destroys the seal before it can even be used.
Filled PTFE gaskets - material characteristics
Code | Home | Material Description | Color | Temperature range (°C) | Wear resistance | Extrusion/pressure resistance | Abrasiveness on the surface | Typical applications |
E71 | Virgin PTFE | Pure, unfilled PTFE. Excellent chemical inertness and very low friction. | White | -254 → +232 | ★☆☆☆☆ | ★☆☆☆☆ | ★☆☆☆☆ (very mild) | Cryogenics, gases, low pressures |
E72 | Pigmented PTFE | Pure colored PTFE, slight improvement in creep and permeability. | Turquoise | -195 → +232 | ★★☆☆☆ | ★★☆☆☆ | ★☆☆☆☆ | General applications, non-abrasive fluids |
E73 | PTFE + fiberglass | 25% glass filler, improves mechanical strength and thermal stability. | Grey | -130 → +300 | ★★★★ ☆ | ★ ★ ★ ★ ★ | ★★★★ ☆ | Cylinders, rods, hydraulic media |
E74 | PTFE + glass + MoS₂ | Glass/molybdenum blend: reduced wear and lower friction. | Grey | -130 → +300 | ★★★★ ☆ | ★★★★ ☆ | ★★★ ☆☆ | High pressures and moderate speeds |
E75 | PTFE + graphite | Excellent lubricant, good dry behavior, aggressive chemistry. | Noir | -155 → +288 | ★★★★ ☆ | ★★★ ☆☆ | ★★☆☆☆ | Chemicals, vacuum pumps |
E76 | PTFE + carbon-graphite | Improves thermal conductivity and dimensional stability. | Noir | -155 → +300 | ★★★★ ☆ | ★★★★ ☆ | ★★☆☆☆ | Valves, compressors, dry service |
E77 | PTFE + carbon fiber | High rigidity, low creep, good water and steam resistance. | Noir | -130 → +288 | ★ ★ ★ ★ ★ | ★ ★ ★ ★ ★ | ★★★ ☆☆ | Shock absorbers, pumps, oil/water |
E78 | PTFE + bronze | Excellent in hydraulics, moderate speed and static sealing | Brown | -155 → +260 | ★★★ ☆☆ | ★★★ ☆☆ | ★★☆☆☆ | Rotary hydraulic seals, high temperature energized static seals |
E79 | Mineral PTFE (FDA) | FDA food grade, contact with water, steam, sanitary products. | White | -155 → +288 | ★★★ ☆☆ | ★★★★ ☆ | ★☆☆☆☆ | Food processing equipment |
E80 | PTFE + stainless steel | Resists very high pressures and temperatures; hard material. | Grey | -155 → +315 | ★★★★ ☆ | ★ ★ ★ ★ ★ | ★ ★ ★ ★ ★ | High pressure static, hot environments |
E81 | PTFE + aromatic polyester (Ekonol) | Exceptional wear and heat resistance, low friction. | Beige | -155 → +288 | ★ ★ ★ ★ ★ | ★★★★ ☆ | ★★☆☆☆ | Rotary, high speed, motors |
(PEEK, UHMW and other composites on request)
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