Bearing Failures: What are the Causes & How can you Prevent them?

Welcome back readers! Today marks the sixth installment of our beloved blog in the wonderful world of vacuum pumps. We love to see our dedicated followers return month after month to read the facts from our trusted Precision Pete. Keep your bearings everyone, because that’s what we’ll be discussing in today’s blog, the bearings in your pump and how to prevent their failure.

 

How They Work

Mechanical bearings are essential pieces of equipment in our vast world of machines. Bearings allow rotational and linear movement between two parts, reducing friction and enhancing performance to save energy. Because objects roll better than they slide; bearings contain smooth metal balls, that “bear” the weight of a device, that roll against a smooth inner and outer surface allowing the device to rotate smoothly. If bearings didn’t exist, machine parts would have to continuously be replaced due to friction and wear. Some machines wouldn’t even be possible without them.

 

Failures, Causes, & Repair

There can be a complete mixture of reasons for bearing failures, and sometimes determining the actual cause isn’t very straightforward. For this blog we’ve picked some of the most common causes of bearing failure.

Fatigue –

Fatigue in the bearing is caused by the size of a load. This can happen on the inside or outside of a bearing. The weight causes the balls to create small waves in their path as they roll against the metal, creating tension and compression. Small particles of material eventually start to flake off and create fractures on the surface.

Repair:

Simply replace the bearing and if possible replace it with a bearing that has a longer life expectancy. *Keep in mind tests have shown that less than 1% of bearings will actually reach their full life expectancy.   

Contamination-

Contamination can cause wear and pitting in the bearing from elements like dirt, dust, lint, metal fragments, or grit.

Repair:

Contamination can be drastically reduced by having a clean work space. Make sure the tools being used and even your hands are also clean. Keep the bearing in its original packaging until you are ready to put it on the machine.

Lubrication and Corrosion-

Improper lubrication and corrosion can work hand in hand or be separate problems all together. Improper lubrication, whether it’s an insufficient or excessive amount or just a complete absence, will cause overheating and corrosion. Corrosion can also be caused by the introduction of water, acid, condensation, or broken down grease in the bearing. Moisture can be a result of leaks in the machine or temperature fluctuations.

Repair:

Properly lubricate your bearings and pay attention to when they may need more. Most of the time lubrication problems have nothing to do with the type of lubrication used, but you should be aware whether your machine is designed for grease or oil. Redirect or stop any fluids from coming in contact with the bearing and attempt to use a well sealed brand.  

Loose or Overly Tight Fits-

A loose housing or shaft both cause similar damage to a bearing. The spinning of a loose shaft will create an increase of temperature and small bits of metal that will eventually find its way into the bearing, which will cause more wear. Overly tight fits also produce high temperatures and will cause rings to crack, eventually leading to premature failure.

Repair:

Stop further operation of the machine and adjust the shafts or housing. Examine for any damage or wear that may have occurred.      

Misalignment-

Misalignment of a bearing will create overheating and cause the separator to fail. Misalignment can be caused by the shaft shoulders, spacers, or clamping nuts not being at right angles. The raceway of the bearing will show markings of the ball track going from side to side.

Repair:

Ensure that the shafts and housing are not off-center from the shoulders and bearing seats. This can also be prevented by using precision grade locknuts.  

Brinell and False Brinell Damage-

“True” brinelling refers to permanent deformation of the material during one event. Improper mounting can result in brinell damage through force like blows or excessive pressure that cause denting. Bearings can properly be mounted with a press-fit on the rotary ring. False brinelling is from material wear that occurs over a period of time. An example of false brinelling would be contamination from foreign materials like dirt, dust, or grit that cause wear and pitting.

Repair:

Using greases or lubricants with antiwear additives will help to prevent brinelling. Separate bearings from any external vibrations.

 

Prevention

It is safe to say that bearing failure comes down to wear, fatigue, and stress caused by an array of malfunctions. There are no ways to indefinitely prevent bearing failure in your system, however there are ways to prevent frequency. We can’t stress enough the importance of proper lubrication. Oil is good for use on machine systems with high operating temperatures and speed while grease is preferred for other bearing use because of its easy handling and application. Because most of us here are pump users, it’s important to note the service life of the grease to sustain proper bearing functions. Mounting should be done with the correct tools to avoid damage to the bearing, misalignment, or deflection of a shaft. Selecting the right bearings for your system helps prevent operational stress. Under or overloading can be attributed with temperature increase and unfamiliar noises which will lead to premature failure. The area around your system is just as important as the inside. Separation of outside heat and proper sealing needs to be ensured in all areas of your system to prevent damage that arise from contamination from water, moisture, dirt, or dust.
The first step in preventing system malfunctions starts with the operator. Know your machine and how it operates. Make sure to use proper bearings and equipment that suit your pumps operation. Once again we thank you for choosing Precision Plus. Keep coming back for new blogs and tips to maintain a bearing on your system.

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