Simple and unassuming in its design, hidden in the depths of machinery and unknown by most people who benefit from its applications, the o-ring is a modern miracle of sealing technology. Since it was first patented in 1896, the circular piece of rubber has become an industry favorite seal. Its flexibility, strength and low cost make it the sealing device of choice in numerous projects, from internal combustion engines and airplanes to diving gear and assembly line robots.
While the design has not changed much since its inception, much else has evolved about the o-ring. Advancements in the manipulation of rubber and other materials to create better polymers, improved testing practices and capabilities, and novel characterization technology have all combined to take the manufacture of o-rings to new levels. This article will highlight some of the recent advances in o-ring sealing technology and their importance to engineering projects.
O-rings are used in a variety of working conditions, including very low/high pressures and temperatures, chemically saturated environments, high-friction applications, etc. As such, they must be made of suitable materials for the intended use. Recent breakthroughs in material science have enabled manufacturers to produce a whole new range of materials with improved properties to fit the intended applications.
Many elastomers used in manufacturing o-rings are combinations of two or more chemicals. New technology now enables manufacturers to vary the percentages of each chemical used to increase or decrease the strength of a particular property. Additionally, other compounds such as plasticizers and flame retardants can be used to enhance the specific properties of the material.
Polymers are the fundamental building block of rubber o-rings, and new combinations and types of polymers are being developed to meet the requirements of different operating conditions. These polymers are resilient to high and low temperatures, pressures, chemical corrosion and explosive decompression. They include materials such as FFKM, EPDM and PTFE. Professional help is often required to make a choice of which polymer to use for which applications, and companies like Apple Rubber have made a science out of helping people make the right choice for their o-ring applications.
Advances in nanotechnology allow material scientists to optimize existing materials by improving the surface characteristics of the materials using specially developed compounds. This serves to reduce friction when needed in dynamic applications or increase friction when used in high-pressure environments to prevent slippage. Carbon nanotubes are already being used in fluoroelastomers to reduce friction, reduce permeation, and as a filter.
Manufacturing o-rings is a complicated and delicate process. Many aspects of the manufacturing process of modern o-rings would not be possible without technological advancements like:
- Machine learning to detect defects and flaws in o-rings as they are produced, thus improving overall product quality.
- Software and CAD tools to design and simulate high-performance o-rings suitable for use in different working environments.
- 3-D printing to produce o-rings to exact specifications without any of the hassles of traditional manufacturing.
Testing and Characterization
Characterization involves predicting and studying the properties and behaviors of o-rings under different environmental conditions. Machine learning and predictive analytics tools reduce the risk of o-ring failures by detecting them before they occur, and data gleaned from such observations helps manufacturers improve upon the design and properties of the o-ring. Characterization also aids in the development of stronger and more suitable materials for making o-rings that are resilient to failure.
In the area of testing, specialized equipment has been developed to allow for more rigorous testing, such as stress relaxation, elasticity, compression and chemical corrosion testing. Failure modes and effects analysis also help the engineering community come up with better ways to prevent o-ring failure and improve sealing performance.
The Future of O-Rings
Ten years ago, we couldn’t have predicted with much accuracy how much o-ring technology would have improved by today. Now that it has gotten to where it currently is, we still can’t say much about where it’s going. But one thing is certain: o-rings aren’t going anywhere anytime soon. This tiny piece of circular rubber is a vital part of many machines and engines, across many different industries. It remains to see what improvements we make to it in the coming years.