EPDM O-rings

                                     A Look at the O-Ring

Generally speaking, an o-ring, also called a packing, is a mechanical gasket in the shape of a torus. Or it can be said to be seated in a groove and compressed assembly between two or more parts, creating a seal at the interface. In fact, it is popular and does great favors for the industrial machines.

The size and material of the o-ring vary. In order to optimize the effects, it is important and necessary to find the proper one. The wise selection acquires people to consider the following aspects together, like the chemical compatibility, application temperature, sealing pressure, lubrication requirements, quality, quantity and cost. Taking the available materials for example, they are mainly classified into two categories: thermoplastics and thermosets. The previous kind includes thermoplastic polyolefin, thermoplastic polyurethane and thermoplastic polyamide and so on. The later kind, also known as synthetic rubbers, includes butadiene rubber, ethylene propylene rubber and silicone rubber and so on. And it should be mentioned the design and manufacturing should obey the regulations of the o-ring in ISO 3601 fluid power system.

It is popular for the characteristics of being inexpensive, easy to make, reliable, and have simple mounting requirements. Or it can be said the o-ring is one of the simplest, yet most engineered, precise, and useful seal designs ever developed. With the development of the mechanical technologies and new materials, the applications would become wide. Either static or dynamic applications have been seen. Within those advantages, it is usually employed in the following listed fields.

In terms of typical applications, it is used to prevent from the leakage. As long as the pressure of the fluid being contained does not exceed the contact stress of the O-ring, leaking cannot occur. During the rotation, the pressure is increasing. In this situation, the feature being easily seal high pressure makes it perform well. In fact, during the dynamic applications, it is important to have a moderate surface finish, especially at low temperatures, even though the flexible nature of o-ring materials accommodates imperfections in the mounting parts. Otherwise, it would abrade the surface of the o-ring or prevent the seal from being adequately lubricated by a fluid film. Then, the o-ring is applied into vacuum systems as well, especially the indium ones. Higher mounting forces are used and the ring fills the whole groove. Also, round back-up rings are used to save the ring from excessive deformation.

Above, there are some other things that the o-ring needs to be improved, such on the improvements on the materials. Whatever, it should be believed that it continues to bring great effects to the proceeding industry. Read More