ADVANTAGES OF LATHE CUT SEALS vs. O-RINGS
The ARCHER lathe-cut seal is a circular sealing device made with a square cross-section. The lathe cut seal is engineered to be fully equivalent to the O-ring for use in most applications. Generally, a lathe cut seal is used as a direct replacement for an O-ring or other squeeze type molded seal.
Virtually all industries have recognized the benefits offered by lathe cut seals. They are used extensively in many applications and have gained worldwide acceptance. In short, they have filled the need for a high quality, economical and often better alternative to the O-ring, particularly in static applications.
ARCHER has performed many tests over the years to determine which seal configuration performs best in static sealing applications: the rectangular lathe cut seal or the circular O-ring. These tests and extensive field applications have proven conclusively that the lathe cut seal is clearly equal to, and in most cases, superior to the O-ring in static sealing applications.
Seal failure is usually attributable to the seal’s inability to maintain either its design shape or dimensional stability. Lathe cut seals have a greater ability to keep their design shape under stress and therefore have a longer effective sealing life.
Several factors influence the ability of a seal to maintain its design shape. Among these are seal stress caused by squeeze, extrusion caused by pressure, and the permanent deformation caused by the seal during use.
Seal Stress Caused By Squeeze
Pressure-energized seals rely on squeeze to form the seal, but excessive pressure can overstress the material and produce premature seal failure. Tests have proven conclusively that the minimum squeeze required to maintain a positive seal using a lathe cut, is considerably less than the minimum squeeze required to maintain a positive seal using a molded O-ring. In the application, the O-ring approximates the inherent shape of the lathe cut seal. The lathe cut seal, in an identical gland, is deformed less under squeeze, minimizing internal stresses and lessening the tendency for the elastomeric material to age prematurely.
Extrusion Caused By Pressure
When system pressure is applied, the seal, either O-ring or lathe cut is forced toward the low pressure side of the gland. The total stress on the seal is the result of the compressive force and the system pressure. The higher the system pressure, the tighter the seal squeezes into the clearance gap. When pressure exceeds the seal’s capacity to bridge the gap, extrusion takes place and nibbling results. Reduction of the clearance gap increases the seal’s ability to seal higher pressure. If the clearance gap can be eliminated pressures as high as 100,000 psi may be sealed with a lathe cut seal.
Lathe cut seals have demonstrated the ability to resist extrusion under high pressures better than molded O-rings. Actual test data show that the lathe cut seal can withstand pressures at least 25% higher than O-rings before extrusion begins. And, of course, extrusion severely reduces the life of the seal.
Permanent deformation and loss of retained sealing force caused by a breakdown of the seal material during usage are major causes of seal leakage. The greater the permanent deformation of a seal under load, the shorter the seal life.
In summary, the ARCHER lathe cut seal is a better alternative to the O-ring because it is:
- Interchangeable with O-rings, size for size, from 3/16” up to 18” OD
- Fits the same gland as standard O-rings
- Outperforms and outlasts O-rings in most static applications
- Less costly than O-ring
- Offered in the same materials as O-rings
- Closer cross-sectional tolerances can be achieved on the lathe cut seal than on most O-rings
- Eliminates the parting line and mold flash.
Contact an engineer today to find out more about how lathe cut seals could best serve your application needs.