Spring Energized Seals

The spring-energized seal, a U-cup lip seal made from specially-formulated polymers and reinforced by an energizing component, can be a valuable tool in the engineer’s problem-solving arsenal. While it may not be suitable for every application, the design has an impressive track record in environments considered too aggressive for other seal types. If getting more performance and reliability out of your designs is the challenge, a spring-energized seal could be the solution.

What does a spring-energized seal do?

Spring-Energized Seal Advantages

The spring-energized seal is capable of providing longer service as compared with conventional (non-energized) polymer or elastomeric seals. This is because contact pressure at the sealing lip remains high throughout the life of the seal. Even as seal materials wear, the energizer compensates for angular misalignments across a wide working spring force deflection range to maintain constant and even force across the seal lip, maintaining sealing pressure. This inhibits the formation of leak paths, which results in fewer maintenance intervals and increased equipment uptime. In addition to promoting even wear and maintaining constant pressure throughout the life of the seal, the spring-energized seal also reduces media contamination by incorporating chemically compatible, wear-resistant materials. This reduces the possibility of premature degradation.

How a Spring-Energized Seal Works

A spring-energized seal usually relies on interference for retention in the housing and to apply pressure at the sealing surface. During installation, the static seal lip is compressed into the housing bore, and the dynamic lip is stretched over the dynamic surface (piston). The compression load applied to the seal causes a reactive force generated by the compressed energizing spring. This precise interference between the sealing lip and sealing surfaces establishes a barrier that prevents the media from leaking past the seal. Effective sealing requires some contact stress between the seal lips and the hardware. This stress, and the resulting friction, can be controlled by adjusting the jacket geometry, material, and energizer force.

Manufacturing Capabilities

Metro Plastics has large diameter seal machining capabilities to micro seal machining capabilities to allow us to provide our customers an advantage in product development. Metro Plastics’ precision machining techniques allow for repeatable, extremely tight tolerances. The environmental controlled machining facility in conjunction with ongoing process controls provides our customers with the consistency of quality and dimensional stability required for ultimate product performance. Tooling design and material science expertise provides excellent machined surface polymer finishes for the broad range of materials that are utilized.

CNC Large Diameter Machining: 15” (381mm) to 110” (2794mm)

CNC Micro Diameter Machining: Less than .040” (1mm) to 5” (127mm)

CNC Diameter Machining: Up to 18” (457.20mm)

CNC Diameter Machining: Up to 22” (558.80mm) with Live Center Tooling

Stress Relief Oven

CNC Milling

Spring-Energized Seal Service Types

Spring-Energized Seal Applications

A spring-energized seal is an ideal choice for operating environments with challenging pressures, temperatures, speeds, and aggressive media. It can outperform elastomeric seals and improve the performance and reliability of equipment used across a wide range of industries and applications, including medical, aerospace, energy, and robotics.

Seal Jacket Materials

A spring-energized seal jacket can be manufactured from almost any base material. But the unique physical properties and performance characteristics of these polymers make them ideal for sealing service:

Polytetrafluoro- ethylene (PTFE)

PTFE Graphite filled seal

Graphite-filled PTFE

Polyether ether ketone (PEEK)

Ultra-High Molecular Weight Polyethylene (UHMWPE – PE)

These materials can be used in their unfilled (virgin) form, or they can be filled with graphite. They are sintered, and can be machined to very tight tolerances. Filled seal jacket materials significantly outperform virgin materials in harsh,  viscous, abrasive, and rigorous operating conditions, and typically deliver longer service life than virgin materials, depending on the type and percentage of filler used. Seal materials conform to hardware surface irregularities and prevent the formation of leak paths.

Seal Energizers

Choosing the right energizer—with the ideal combination of force, fit, and finish—is as critical to the success of a seal’s design as the material itself. Popular energizer components for the spring-energized seal consist of:

Canted Coil Springs

Helical Springs

Cantilever Springs

Seal Energizer Materials

Media resistance, galvanic compatibility, and biocompatibility are key factors that impact the selection of seal energizer materials. Although it’s not uncommon to find energizers made from elastomers and even polymers (such as PEEK), metals are often the more popular choice because they offer greater durability and design flexibility. Metal energizers can withstand higher operating temperatures, resist compression set, and allow for more precise control over a wider range of forces.

Spring-Energized Seal Experts

At Metro Plastics Technologies, we’ve perfected the process of designing and manufacturing custom spring-energized seals. Our products are machined from polytetrafluoroethylene (PTFE) and other premium polymers, and energized with precision-engineered canted coil springs. To learn more, please view our catalog below and reach out to Metro Plastics.