Archive: Jan 2016

The Importance of Proper Grease and Lubrication

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Rolling bearings are precision bearings, such as balls or rollers, which carry loads in a variety of applications with relatively little resistance. They are durable in even the toughest conditions and maintain a long service life; this can be projected as a period of time or a total number of rotations depending on the application.

Mechanic lubricate a roller bearing with lithium greaseOver 99% of rolling bearings reach their expected service life. In fact, most causes of premature failure, such as rust, corrosion, pitting, and skewing, are preventable. To protect rolling bearings from long-term damage and premature failure, you can cover the sliding contact surfaces with a thin film of lubrication that separates the rollers and raceways.

Engineers typically use grease to lubricate bearings because it is easy to handle and offers protective sealing capabilities for the system. Another lubrication option is oil, which flows freely and carries away heat, making it suitable for high speed or high temperature operations.

When applied properly, rolling bearing lubrication can:

• Reduce the friction and abrasions caused by direct metal-to-metal contact
• Transport heat generated by friction
• Prolong overall bearing service life
• Prevent harmful rust and corrosion
• Prevent foreign objects and contamination from interfering with the rolling elements

Just as normal rolling bearings have an expected service life, grease does as well. Engineers must consider this factor and diligently reapply lubrication to sustain proper bearing function. When done effectively, lubrication enhances bearing reliability and increases overall service life.

Lubrication is a crucial part of rolling bearing success, but it’s important to be mindful of some potential pitfalls:

• Selecting the wrong lubricant type – Grease and oil each have their own advantages and disadvantages, depending on the specific application.
• Using too much or too little grease/oil – Too much grease can cause bearing temperature to rise, especially when operating at high speeds, while too little grease results in harmful metal-to-metal contact.
• Mixing grease and oil – Each type of lubricant provides different benefits, but they should always be used separately.
• Contaminating the grease/oil with objects or water – The lubricant’s primary function should be to seal the contact surface and prevent the entrance of media or water.

Action Bearing has had “Bearings on the Brain” for over 50 years. Whether you’re looking for a hard-to-find bearing or need help selecting the right type of lubricant for your system, our team of specialists will examine your application and make an expert recommendation.

For more information about the vital elements of rolling bearings, we invite you to download our eBook The Art of Precision Bearings or visit our website.

Bearing Failure Modes

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Precision bearings are industrial components that carry loads in a variety of applications. Roller bearings, which operate with rolling elements such as balls or rollers in a raceway, are reliable and durable. In fact, more than 99% of rolling bearings reach their projected service life, even in the toughest conditions.

bbWhile only a small percentage of such bearings fail, this premature failure can be caused by a number of factors. Flaking, pitting, spalling, rusting, corroding, creeping, and skewing can all lead to failure; each concern stems from a small group of interrelated and preventable causes. Some of the most common ones include:

Improper lubrication – Lubrication enhances function and prolongs bearing service life, but only if done correctly. Too much or too little grease, mixed lubricants, and contamination can all have adverse effects on the bearings. Lubricated bearings also have a “grease service life,” which is a state of optimal function between lubrications. If an engineer neglects to reapply lubrication when this time expires, the bearing can fail.

Mounting and installation of bearings – It is crucial to use proper tools and heaters during the mounting process. If mounting pressure is applied to the wrong ring during installation, particularly with self-aligning bearings, the raceways and rolling elements can become dented. If the fit is too loose, tight, or misaligned, the preload weight will be skewed and could cause the shaft to rotate or creep.

Operational stress and bearing selection – Although roller bearings are generally reliable, the overall application they work within may change over time. If the load within an application becomes too high or too low, bearings could fatigue or skid, respectively. Warning signs of these failures include rising temperatures and unusual noises.

Environmental influences – Dust, dirt, media, water, and unwanted heat can all contaminate your bearings if they’re not properly sealed. Depending on the application, a bearing may require insulation to prevent electrical currents and sparks. Be mindful of outside factors that could interfere with your specific application and be aware of precautions you could take to prevent such problems.

Considering different bearing technologies and identifying the one most suitable to your specific application is the first step in the prevention of bearing failure. By keeping these causes and their warning signs in mind, you can proactively make corrections to avoid premature failures and additional costs.

Action Bearing has over 50 years of ball and roller bearing expertise. We serve original equipment manufacturer (OEMs) and maintenance markets around the world to help customers find the right bearing at the right price. To learn more about the causes and cures of premature bearing failure, we invite you to read our eBook, “Bearing Failure Analysis.”