This article will discuss how we understand and control friction in dynamic sealing applications.
It’s easy to stop a leak in a system by just welding it shut. But when you create a dynamic application, you generally have a limited amount of power to move the device you’re sealing.
Friction is a force that must be overcome in all moving pieces. Controlling friction allows us to make efficient equipment that can have a long wear life and move with a limited amount of force.
There are many factors that drive friction up or down in a dynamic application. Although this blog will focus on shaft seals, the same considerations apply to piston or face seals.
Below we’ll cover the following factors and how they affect the friction calculation in our seals:
As a seal supplier, we usually like shaft materials to be hardened steel with surface finishes that are highly effective. Hardness above 50 Rc usually gives long wear life.
Having a good finish of 8 Ra. will insure long seal life and carry lubrication. However, depending on the application, there are times when a super finish of 2 or 3 Ra is justified.
Depending on shaft loading, there are many choices of surface finish that can reduce friction and improve the life of the seal. Understanding the bearing load under the seal helps to understand what finish is required to withstand the operating conditions.
There are some finishes that are detrimental to seal life. An example is a heavy chrome surface that looks sturdy, but usually can’t be ground smooth and is left with large peaks or valleys. Thin, dense chrome is often the opposite, giving good seal life if applied correctly. The engineers at Eclipse Engineering are prepared to make recommendations on hardness and finish.
Being commodity items, U-Cups are readily available in a number of materials and can be found on-the-shelf from multiple distributors and manufacturers in many standard sizes.
Named for the shape of their cross-section, a U-Cup’s design will be pressure energized increasing sealing effectiveness when compared to a standard O-Ring.
This means as pressure increases, the sealing lips are continually forced into the mating hardware surface, ensuring good contact at all times.
The simple and easily moldable design is an effective sealing solution to many systems in both hydraulic and pneumatic applications. Modifications in lip thickness and inclusion of an O-Ring Energizer can tailor sealing loads and wear life to specific situations.
A key advantage to an elastomeric U-Cup is the relatively small and simple hardware space needed. Because of their flexible compounds, most U-Cups can be installed in a solid gland configuration.
A basic ID or OD groove is all you need for proper seal retention. Plus, no special tools or considerations need to be taken for correct installation.
U-Cups are available in many of the same compounds as standard O-Rings such as Nitrile, Fluorocarbon, and EPDM, but polyurethanes may be the most common material.
Urethane provides a good combination of elasticity/pliability and toughness. Therefore, it exhibits good sealing characteristics as well as, durability and wear resistance.
These desirable qualities make U-Cups an optimal solution for many sealing systems across multiple industries and they can be found in countless standard products. But Eclipse is approached many times a year with customers pushing the limits of standard U-Cups and in need of better solutions.
Eclipse was approached by a leading pneumatic cylinder manufacturing seeking a sealing solution for a unique application.
While U-Cups typically provide optimal sealing performance in pneumatic cylinders, this application presented a difficult challenge.
The air cylinder was to be used as an actuator for a latch on a large industrial oven. While pressures, speeds, and cycle times were nothing out of the ordinary, the temperature at which it had to operate at was — a continuous 500°F.
Gallagher recently recorded the Rubber Energized Seals webinar, discussing rubber energized rod or piston seals, and the advantages and disadvantages to using some of the most common seal profiles. This webinar is presented in conjunction with one of our trusted partners, Eclipse Engineering, Inc. Eclipse is a designer and manufacturer of high performance engineered polymer solutions.
This section of the webinar will discuss cost vs. lead time in rod and piston seals, as well as how to choose the right seal for your application.
To view the webinar in its entirety, visit our Resources
Gallagher recently recorded the Rubber Energized Seals webinar, discussing rubber energized rod or piston seals, and the advantages and disadvantages to using some of the most common seal profiles. This webinar is presented in conjunction with one of our trusted partners, Eclipse Engineering, Inc. Eclipse is a designer and manufacturer of high performance engineered polymer solutions.
This section of the webinar will discuss some of the more common profiles for rubber energized seals, including x-rings, u-cups, buffer rings, cap seals, etc.
To view the webinar in its entirety, visit our Resources page and fill out the form, or
Gallagher recently recorded the Rubber Energized Seals webinar, discussing rubber energized rod or piston seals, and the advantages and disadvantages to using some of the most common seal profiles. This webinar is presented in conjunction with one of our trusted partners, Eclipse Engineering, Inc. Eclipse Engineering, Inc. is a designer and manufacturer of high performance engineered polymer solutions.
This first section of the webinar will discuss some of the things you should consider when designing a seal for an application, as well some of the more basic seals, such as o-rings, gaskets, etc.