Rubber O.D. wall type Provides stable sealing performance around the seal O.D. surface.

Modern engine oils, such as the current SG classification for gasoline engines, contain a large fraction of additives, many of which are detrimental to fluoroelastomers. The primary functions of oil-additive packages are to protect metal parts, avoid deposits in the engine, minimize oil degradation, and adjust fluid viscosity. Little attention has been paid to avoiding damage to rubber seals. Instead, elastomer producers have been expected to provide new, higher-performing products at no increased cost to auto manufacturers. Among the additives with moieties that may attack fluoroelastomers at high temperature are detergents (phenolates), dispersants (succinimides, alkylphenol amines), and antioxidants (amines, sulfides, hindered phenols).⁴ Many of these components are multifunctional, containing phenol or amine groups that can dehydrofluorinate and crosslink VDF-containing fluoroelastomers, leading to loss of elongation and eventual embrittlement. However, the rate and extent of reactions with seals are affected by many factors, including whether air is present in the system. When oil is exposed to air at high temperature, additives may undergo considerable changes. For example, a significant fraction of amines may be oxidized to amides, which have little effect on fluoroelastomers.⁵

1. What are oil seals?

Metal-cased oil seals are usually installed in a housing bore made of the same material. This allows for equal expansion and contraction of the materials during operation, preventing leakage. This type performs best when used in a steel housing.

One option is to buy oil seals from specialised gasket and sealing material companies like Polymer Trade Manufacturing Ltd, which is known for its expertise in dealing with gaskets and o rings. These companies not only offer an extensive range of oil seals but also provide expert advice to help customers select the right sealing materials for their specific requirements.

Oil leak: the most frequent failure of the oil seal

Elring

For a more detailed discussion of seal types and type codes, please see the following:

The seal shown in Fig. 14.2 is a relatively simple design; most automotive seals are more complex. Dust lips are often used to keep outside contaminants away from the oil lip seals; such seals thus have undercuts that make demolding more difficult. Fluoroelastomer compounds used for such undercut shapes must have reasonably high elongation at break at molding temperatures to avoid tearing the part during demolding. The metal insert is often U-shaped, and stock may be molded to form a thin layer over the outside of the insert. Since both compression and injection molding methods are used, suppliers of fluoroelastomers for shaft-seal applications often must provide different versions of the same polymer composition-medium to high viscosity for compression molding, and low to medium viscosity for injection molding. Different precompounds may be necessary to accommodate relatively long compression-molding times at low temperature and very short injection-molding times at high temperature.