Applications - Automotive - O-Rings
O-Rings are used in automotive applications for sealing a variety of fluids. O-Rings typically are used to seal between two surfaces. The o-ring presses against both surface with enough force that the fluid or gas can not escape. Because of the way most o-ring grooves are designed the o-ring is actually pushed into the gap between the mating surfaces by pressure on the other side.
Important properties for an o-ring is the ability to maintain its sealing force, usually measured as compression set or compressive stress relaxation, and the ability to maintain its sealing ability under temperature changes and different fluid exposures.
O-Rings are exposed to the following:
Temperatures from -40C to 200C
Fluids ranging from Engine Oil, Transmission Fluid, Power Steering Fluid, Refrigerant, Compressor Oil, Coolants, Brake Fluids
Pressures up to 2000psi
Additional Application - Power Steering
In general, power steering systems require seals around a rotating shaft and a reciprocating rod or hydraulic ram. The rotating shaft seal must withstand constant rotational wear during pump operation. The reciprocating seal must maintain hydraulic pressure in the system and withstand incremental wear when the rod or ram moves with the vehicle steering linkage.
Key factors in seal compound design include:
Low compression set.
Retention of physical properties at elevated temperatures.
Resistance to fluids and fluid additives.
Low volume swell and extraction.
Resistance to assembly damage.
Retention of sealing properties at low temperatures.
Since these parts are typically injection or compression molded, a lower viscosity polymer is preferred to insure effective molding.
Environmental considerations for power steering seals include:
Aging resistance in air and fluids at 150°C.
Resistance to typical fluids including Pentosine CHF-11S, IRM 903, Mercon ATF, MS 9602, and Esso IMP 6148.
Reduced Coefficient of Friction (COF).
System improvements over recent years have been aimed at reducing noise, bumping, and hammering at low speeds. New seal design and higher capacity pumps using fluids that are more aggressive toward deterioration of the rubber compound have addressed these problems, as well as issues such as shake and vibration. This has resulted in higher performance requirements from the base elastomer in the seal formulation.
In the attached formulation, Zetpol 2010L is the polymer of choice for rotating and reciprocating shaft seals.
Zetpol Hydrogenated Nitrile Elastomers
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