by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

Spring Energized Seals vs. O-Rings

As long as your application involves static pressures, no extremes in either temperature or pressure, and no corrosive chemicals, an elastomeric o-ring will probably suffice. But things become more challenging outside of those conditions and you will need a better sealing solution: a spring energized seal.

O-Ring Seals

O-rings are a common type of seal that’s used in a wide variety of applications. Elastomeric o-rings are made from materials such as silicone, Neoprene, Nitrile, Buna N, and EPDM Rubber and consist of a toroid with a circular cross-section. In fact, the official definition of an elastomer component is that it does not break when stretched 100% (i.e., stretches to twice its original length). 

O-rings can effectively provide a barrier to prevent fluids from leaking and work well for static applications and some dynamic applications as long as there are no extremes in pressure or temperature. However, there are times when a spring-energized seal provides a better sealing solution than an o-ring. 

O-rings often fail due to issues with clearance as high pressures, large temperature changes, or cyclical changes in either pressure or temperature, all of which can cause dimensional changes that force the o-ring into the seal extrusion gap and cause excessive wear that leads to premature failure. In addition, environmental conditions and temperature changes can lead to the elastomeric material becoming brittle, thus losing its ability to stretch and compromising its ability to provide an effective seal.

Spring-Energized Seals

The spring energizer seal is the engineer’s choice when O-Rings cannot provide adequate seal performance.The energized seal applies a consistent force that enables the lip to adapt to the contact surface as it rotates. Because of this, spring-energized seals are often used to effectively maintain a seal even when there are challenges such as vacuum pressures, eccentric contact surfaces, runout, and hardware gaps. In short, where other static and dynamic sealing options fail, spring-energized seals rise to the task.

Operating Conditions Where Spring-Energized Seals Excel

Despite the additional cost, spring-energized seals are preferred over elastomeric o-rings when there are …

  • Extreme pressures (including vacuum pressures)
  • Extreme temperatures (including cryogenic environments)
  • Dynamic (as opposed to static) pressures
  • Corrosive media (when materials such as PEEK and PTFE are used)
  • Cyclic pressures or temperatures

In such conditions, even the best elastomeric O-rings will start losing their ability to seal. They can become brittle in extreme temperatures, and exposure to corrosive media will accelerate their natural wear. Using O-rings in such operating environments can seriously compromise the reliability of equipment and the safety of personnel, not to mention potential environmental impacts.

Additional Benefits

Also keep in mind that spring-energized seals are available with FDA approved jacket materials such as PTFE and PEEK that make them safe for use in applications such as food processing, pharmaceutical, biochemical, and medical. Their extreme durability makes them ideal for harsh environment industries such as petrochemical, oil and gas, and aerospace. 

Conclusion

When all other sealing solutions fail, a spring-energized seal is likely the answer. They consistently provide reliable sealing in operating environments that destroy o-rings, and in turn enhance the dependability, safety, and performance of the equipment that depends on them for proper operation. 

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by Jackie Johnson Jackie Johnson No Comments

The Different Types of 3D Printing, Part 2

Last week, we talked about a few of the 3D printing technologies that are on the market. Today’s blog post is a continuation of last week’s post, with even more 3D printing methods to discuss!

DLP

Digital Light Processing (or DLP) uses a projector to cure photopolymer resin. DLP printing is very similar to SLA, the differencing being the use of a safelight instead of a UV laser. Also, like SLA, DLP creates highly detailed objects with very little visible layers. And while DLP can print much faster than SLA, the objects printed have similar properties.  Benefits of DLP printing include:

  • Highly Reliable System
  • High Quality Prints
  • Easier to Maintain than SLA Printers
  • Cheaper than Most SLA Printers

MJF

Multi Jet Fusion (or MJF), developed by HP, is unique in that it uses inkjet to create a 3D-object. An inkjet array selectively applies fusing and detailing agents across a bed of nylon powder, which are then fused by heating elements into a solid layer. This process repeats itself until the object is formed. After that, the entire powder bed is moved to a processing station where loose powder is removed and then bead blasted and dyed. Benefits of MJF printing include:

  • Lowest Cost to Print
  • More Design Flexibility
  • No Supports Needed
  • Benefits of Being Backed by HP

DMLS

Direct Metal Laser Sintering (or DMLS) is one of the best ways to make functional metal prototypes and parts. The process begins by sintering each layer with a laser aimed onto a bed of metallic powder. The powder is then micro-welded and the process is repeated layer by layer until an object is formed. Benefits of DMLS include:

  • Ability to Print Complex Parts
  • High Quality Prints
  • Rapid Print Speed
  • Print is Strong and Durable

EBM

Electron Beam Melting (or EBM) is very similar to SLS printing. There are, however, several key differences- the most significant differences being that the energy source comes from an electron beam instead of a CO2 laser, and that EBM printers work with conductive metal instead of thermoplastic polymers. The benefits of EBM printing are:

  • High Density Prints
  • Fast Printing Process
  • Non-Sintered Powder can be Recycled
  • Fewer Supports Needed

3D printing has evolved and expanded since it’s beginnings in the 1970s. Since then, there have been several different 3D printing technologies created, each with their own pros and cons. Regardless of material used, time and budget, there is a printer for you.