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2 min read

Waterproof Bearings: Why Replace Stainless with Plastic?

By Dave Biering on October 31, 2017

Rulon W2 waterproof bearings excel in water meters without leaking or absorption

“You want to replace tough bronze bearings with plastic?” This was the comment one of our OEMs heard when attempting to retrofit their metal waterproof bearings with a plastic material on a water meter assembly. We were up to the challenge of answering this critical question, with this reply:

Customer questions posed to our Ask the Experts portal are always answered, as this engineer discovered when he described his situation:

The background

This manufacturer produces fresh-water industrial meters, and needed to replace a porous Oilite bronze bearing that was slowly leaching oil into the water. The oil not only contaminated the water supply but the bronze contained lead. The engineer also noted that the meter’s bronze hardware was incompatible with the stainless shaft which could lead to a cathodic reaction. The incompatibility caused the meter to give unreliable data readings on the water flowing through the pipes.

The recommendation

Our recommendation was to replace the bronze bearings with Rulon W2. While most filled-PTFEs are reserved for dry applications, Rulon W2 fluoropolymer contains an additive to enable waterproof service with minimal (to no) moisture absorption.

The result

After some initial hesitation about the durability of Rulon W2 vs. traditional bronze water meter bearings, our client agreed to testing. Results were overwhelmingly positive, as W2 eliminated oil leakage, and the material’s self-lubricating properties also eliminated abrasive wear on the stainless hardware. Rulon W2 provides one of the best wear and friction rates, plus good thermal dissipation for a longer service life – without replacement for years at a time. Explore more Rulon technical case studies.

Rulon W2 waterproof bearings excel by:

  • Eliminating stick/slip
  • Reducing abrasion in mating hardware
  • Providing dimensional stability in fresh and chemical environments
  • Ending moisture absorption
  • Ensuring compatibility with drinking water (DWGV certified in Europe)

While our client had excellent results with their Rulon W2 waterproof bearings, we also cautioned them about the prevalence of counterfeit bearing materials posing as genuine Rulon. Unfortunately, counterfeiting remains a challenge in industrial bearings, according to the World Bearing Association.

As the exclusive North American distributor of Rulon, only TriStar can guarantee the authenticity and proper processing controls are used in manufacturing. Read more in our paper, Rulon: How to Recognize Genuine and Avoid Counterfeit.

Rulon Bearings - How to Recognize Genuine and Avoid Counterfeit

Topics: waterproof bearings
2 min read

Q&A Waterproof bearings: What are the benefits of plastic?

By Dave Biering on May 24, 2016

Waterproof bearings: What are the benefits of plastic?

Have you posted your design question to our Ask the Experts portal? It may be featured in our weekly blog, which is where this post comes from! A designer of offshore marine products wanted to review the benefits of waterproof bearings. And the top answer is that plastic waterproof bearings eliminate corrosion, which is one of the primary causes of metal bearing failure in a water environment. 

Here’s how:

First, let’s review the term “waterproof bearing,” as it is a bit of a misnomer. Bearings that provide the best “waterproof” service are resilient to liquids beyond just water. They should also resist corrosive liquids such as slurry, salt water and chemicals, plus the damaging effects of water spray. In many design circles, bronze and stainless steel are the preferred materials for submerged and marine applications. And these materials provide good service ― until they begin to corrode. 

The simple truth is that metal bearings and water (or other liquids) are only compatible for a certain length of time before bearing corrosion sets it. Eventually, chemicals, sea spray and other contaminants will cause the bearing to flake and peel, before failing altogether. In fact, rolling element bearings that are exposed to water at a rate of even 2% can have a reduced life expectancy of 50%. Liquids cause the films in metal rolling bearings to become contaminated, which leads to corrosion and early failure. 

Unlike pure metal bearings, plastic bearing are a hybrid of engineered polymers and composites that easily resist water and corrosion. Plastics never absorb moisture, which means they will not swell or impact the equipment mating hardware. And because they are self-lubricating, there’s no need to manually grease plastic bearings. Given the cost and labor of manual greasing, self-lubricating plastics can create a significant cost savings. 

Plastic waterproof bearings provide many benefits:

  • Resistance to water, chemicals and slurry
  • Longer life span without corrosion or failure
  • Dimensional stability in heavy-duty environments
  • Excellent service in marine pumps, cranes, davits, winches, motors
  • Industry certification for shipboard use

With a great combination of strength, corrosion-resistance, and grease-free service in linear, oscillating and rotary applications, look to waterproof plastic bearings. Here’s 5 reasons Ultracomp bearings excel in a marine environment. 

Bearing Selection: Get the Ultimate Plastic Bearing Design

Topics: waterproof bearings