Search Results

Methyl-Vinyl Silicone rubber, with its unique combination of low temperature flexibility and high temperature stability, finds use in many sealing applications. However, the relatively low tear strength of Silicone rubber introduces premature damage problems with Silicone seals. In addition, Silicone rubber reverts with exposure to high temperature and lubricating oils. The work reported here was performed to gain a better understanding of Silicone reversion in hot lubricant.

Oil Resistant elastomers are used in a wide variety of applications for the retention of lubricant and/or the exclusion of contaminants. These elastomers are formulated to produce specific static and dynamic properties. However, at elevated temperatures, the lubricants that the elastomer components are designed to seal can cause long term property deterioration of the elastomer. This paper will focus on the effects of lubricants on seal elastomers with emphasis on base oil trends, specific additive effects, synthetic lubricants, and the combined effects of high temperature, lubricant and oxygen.

In this experimental investigation of the sealing mechanism, the rate of oil leakage through the gap formed by rigid seals and the shaft was measured as the function of the shaft speed, oil level, oil temperature and the gap geometry. It has been found that the oil can dynamically seal itself within a range of the shaft speed, even when the gap size is relatively large. This sealing phenomenon is due to the rotational oil flow generated by the shaft. The results of the investigation suggested that the radial seals can be functioning under the unfavorable condition of a gap between the shaft and the seal lip, if the operating parameters are carefully chosen.

Finite element analysis (FEA) computer programs have been available for engineers' use as a design tool for more than two decades. They were adopted by the radial lip seal industry a decade ago. Now, FEA is a necessary tool because it has proven its capabilities in the seal industry, and seal customers are requiring it as a design verification instrument. This paper gives a brief description of the three phases that the engineer undergoes to perform FEA on a design: modeling, solving, and interpreting. Also, it discusses six studies that used FEA on sealing products for design verification, trouble shooting, and optimization. These few examples demonstrate how finite element analyses are used as a design tool in the radial lip seal industry.

The development of the highly saturated nitrile family of polymers has enabled elastomeric compounds to be developed for both rotating and reciprocating seal applications with good high temperature performance combined with the relatively good low temperature performance associated with conventional nitrile compounds. The paper will discuss a number of compound development programs and illustrate results obtained from both laboratory and seal tests making reference to use of the new compounds in pinion, steering gear and engine seal applications.

Contamination of sealed systems from the outside not only affects the performance and life of a sealed mechanism, but also that of the seal itself. Many dust and dirt exclusion systems have been offered by manufacturers, including various radial and axial auxiliary lips. The tests described in this paper investigate the effect of several auxiliary dirt lips on seal life in a dust environment. Since many of these designs provide interference to the shaft for both primary and secondary lips, the tests also examined vacuum formation between the lips and its effect on the seal.

A unique bonded polytetrafluoroethylene (PTFE) wafer radial lip seal has been developed for sparsely lubricated diesel engine crankshaft applications. The paper compares the design and performance of the bonded PTFE wafer design to an assembled PTFE wafer, laminated PTFE, and conventional fluoroelastomer seal designs. The PTFE wafer seal substantially extends seal life beyond fluoroelastomeric seals because of the lower temperature present at the sealing interface.