Seals — Machine Elements of Increasing Importance

Abstract

With the advent of the Industrial Revolution, moving machinery, containment of pressure, separation of fluids and many other conditions which require what we collectively call sealing, arose. Seals that were used in those days are the forefathers of the many types of modern seals that comprise one of the most frequently used machine elements.

The evolution of seals and their development in the future reflects the technology of the day and consequently the needs of society. Societies are undergoing rapid changes. The population growth is coupled to the high growth of information and communication systems, leading to an explosion of knowledge. The consequence of this is the speeding up of the rate of technological breakthroughs but also more sophisticated and demanding customers and end users.

When the above is coupled to the intense competition in today’s markets, it follows that products (and, by implication, their components such as seals) are required to have higher reliability in order that they fulfil the “trouble-free operation” demands of the end user. At the same time, because of the strong competition, there is an increasing demand for “downsizing”, that is, scaling down of machinery or increasing the power throughput for the same size. These two requirements of reliability and downsizing apply to seals as components but also provide a clue to the increasing use of seals as a protective element to obtain the best performance out of machinery. A notable example is the sealing of rolling element bearings where the exclusion of particulate contamination