Back-Up Rings
by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

The 3 Leading Materials for Effective Back-up Rings

There are three leading materials used for most back-up ring (BUR) applications: PTFE, Nylon, and PEEK. Each of these materials has specific benefits that it can bring to your application, starting with their stiffness and compressive strength.

Why Back-up Rings Are Important

Seal extrusion is one of the most common causes of polymer seal failure. Whether the cause of extrusion is a large gap between the mating surfaces, high temperatures, or extreme pressures, back-up rings can help. The right choice of a BUR can prevent seal extrusion, lengthen the useful life of the seal, and reduce the chances of a catastrophic failure.

PTFE Back-Up Rings

PTFE is well-known for its extremely low friction, dry running capabilities, and outstanding chemical resistance. Filled PTFE (either glass, carbon, graphite, or bronze filled) can handle operating pressures up to 5,800 psi, making it an excellent choice for both medium and high-pressure applications. Virgin PTFE has a much lower maximum operating temperature (around 3,600 psi) and is limited to low-pressure situations. PTFE also has a maximum operating temperature of 575°F, and that combined with chemical compatibility and the high-pressure capabilities of filled PTFE mean that it is an excellent option for harsh condition environments.

Nylon Back-Up Rings

Nylon 6,6 (sometimes written Nylon 6/6 or Nylon 66) is a polyamide material commonly used for back-up rings. It can handle high pressure very well but is limited to temperatures below 186°F. It possesses excellent rigidity, good compressive strength, and thermal stability, all of which are key to effective backup rings.

When used for back-up rings, Nylon is typically filled with Molybdenum Disulfide (MoS2) to achieve an even lower coefficient of friction. It is not recommended for use in wet or humid environments because it does absorb water unless fillers such as glass are added to offset the absorption effects. 

PEEK Back-Up Rings

Another commonly used back-up ring material is PEEK, which can handle temperatures of up to 500°F and pressures up to 20,000 psi. Like PTFE, it is low friction, dry running, and resistant to a wide variety of aggressive chemicals. It is also available with fillers to enhance properties such as compressive strength and stiffness. However, PEEK is much harder than PTFE: PTFE has a Shore hardness of D50 while PEEK has a significantly greater hardness of D85. For these reasons, PEEK back-up rings are often used in aggressive environments, such as those found in the oil and gas industry. 

Conclusion

If you are having issues with extrusion-related seal failure, polymer back-up rings are a cost-effective solution that can extend the life of your seals. When it comes to polymer back-up ring materials, the top three choices are PTFE, Nylon, and PEEK. While each has its own pros and cons, they are excellent options for solving the problem of seal extrusion. PEEK works best for high pressure, high temperature environments that can involve exposure to corrosive materials. PTFE can also handle high temperatures and corrosive environments, but its maximum operating pressure is lower than that of PEEK. Nylon is also an excellent choice with excellent hardness and thermal stability, with its main limitations being high temperatures and exposure to humidity and moisture. 

by Jackie Johnson Jackie Johnson No Comments

Additive Manufacturing and its Benefits

You’ve seen them on the internet, in libraries and schools and maybe you even know someone who owns one. 3D Printers have changed the way the world and continue to provide many benefits for a number of industries. But how do they work?

Does additive manufacturing, or 3D printing, benefit the industrial market? Additive manufacturing, or 3D printing, benefits the industrial market by reducing tooling costs, allowing for faster manufacturing, and eliminating the need for inventory.

How Additive Manufacturing Works

With additive manufacturing, objects are designed using computer-aided design software (or CAD software) and are then saved as .stl files which are then digitally sliced into ultra-thin layers. It is these layers that are extruded through a hot nozzle or print head and deposited onto the previous layer. The process is repeated layer by layer until a 3D object is formed. 

There are several different materials used in additive manufacturing. Thermoplastics are the most common materials used. These include PET, PEEK, Nylon, ABS, Polycarbonate, etc. Other materials that are often used include metal, ceramic, rubber, and even bio-materials. 

Additive ManufacturingWhat Are the Benefits of Additive Manufacturing?

The benefits of additive manufacturing, particularly for the industrial space, are many! 

Reduced Tooling Costs

Tooling cost is a major driver in the manufacturing industry. And the upfront cost can impede many low-volume manufacturing companies, where a significant amount of capital expenditure is required before the first unit is even produced. But with the lower tooling costs of additive manufacturing, low-volume manufacturers can finally enter the marketplace.  

Quicker Manufacturing

When the success of a business is won or lost based on speed to market, the ability to quickly manufacture goods is imperative. One sure-fire way to be one of the firsts to market is to leverage additive manufacturing to reduce lead time. With 3D-printing, the production time is reduced by weeks or even months. 

No Need for On-Hand Inventory

While traditional manufacturing requires warehouses full of premade parts and products, additive manufacturing allows a business to have a virtual inventory. Part information is stored in the cloud via .stl files and can be printed on demand. This removes the need for warehouse space, saving businesses space, rent money, and piles of parts. 

Conclusion

Additive marketing, or 3D printing, is the manufacturing process of the future. Because of its ease of use, quick turn-around, and relatively low cost, additive manufacturing (AKA 3D printing) is quickly becoming one of the go-to manufacturing processes for a wide variety of industries.

Contact us today to learn more!