CC and CL Chemical Resistant Bearing Seals

Key Properties

PTFE does not age, it is UV resistant, flame retardant and not hygroscopic. The water absorption is less than 0.01%. PTFE does not melt and is therefore not suitable for injection moulding. In addition, PTFE has the following properties:

• Dual or triple PTFE sealing lip
• Works under high pressure up to 40 bar
• Suitable for unhardened shafts as well
• The ideal choice for high speeds of up to 30 m/s
• For wide temperature range from −79°C up to 260°C
• Excellent chemical resistance
• Suitable for food and pharma applications (FDA-approved)
• Good dry running capability
• Wear-resistant and low friction
• Greatest resistance to fatigue
• Flame resistant – UL94V0
• Antistick properties
• Low co-efficient of friction
• UV-resistant (does not age)
• Not hygroscopic (water absorption < 0.01%)
• Very good dielectric insulation properties

Limited Seal Lift Prevents Penetration of Dirt

Normal stresses in the grease, due to the high shear rates in the shaft area or in the seal contact area, generate a contact force on the seal lip. This is in addition to the lift generated by elastohydrodynamic lubrication. Because of the overall design of the seal, this lift effect will be limited. Therefore the PTFE lips fit more tightly and with more tension around the shaft. This makes it more difficult for dirt to get under the lip and wear a groove into the shaft.

Double protection

In grease-lubricated Extreme Bearings such as the CC seal, it is not only the small gap between the seal lip and the shaft that provides sealing against contaminants. The grease in between the sealing lips also provides a sealing action.

Even though PTFE seals make a great material to protect the bearing against liquids, PTFE makes a poor material against abrasive contamination. PTFE material will wear out fast if abrasive material is present. Therefore we recommend to protect these seals with a HS seal protector ring.

HS Seal protection ring to be mounted in front of other seals to protect these against coarse dirt and external violence.

If the contamination is only on one side of the bearing unit, a seal combination such as those shown in the diagrams can be chosen. By refilling the grease on this side, it will flow and be released from the bearing housing and the contamination along with the grease will flow away from the sealing lips.

The list below shows the chemicals, fluids and gases against which the PTFE sealing element of CC and CL seals is resistant. A check mark in a temperature column means the seal can handle that medium at that temperature. Empty cells indicate no recommendation or no data for that temperature.

Indicative values based on industry compatibility charts (Parker O-Ring Handbook, Trelleborg, ERIKS). The end user is responsible for validating suitability for their specific application — concentration, pressure, mechanical stress and exposure time matter. When in doubt, contact Extreme Bearing for a tailored recommendation.

Tips for mounting CC and CL seals:

• PTFE shaft seals are press fitted into receiving hole.

We recommend the sealing rings are glued into the receiving hole. Use sealing compound (e.g. Loctite 601, 641)

• Use conical fitting tool to protect sealing lip
• Before fitting, the seal lip must be inspected for contamination/damage
• The sealing lips must not be deformed
• These seals require expert installation

It is important when mounting a CC and CL seal that there is a tapered end on the shaft. The required dimensions are given here in mm.

The seal in the housing is quite tight, this can make assembly a bit difficult. You can, with tact, stretch the seal a little. Use for example something as a smooth handle of a screwdriver.