Effective Bearing Lubrication: Practical Tips for Maintenance Teams

Bearing lubrication plays a crucial role in extending the lifespan of bearings and ensuring smooth machinery operation in industrial environments. Improper or inadequate lubrication is a leading cause of bearing failures, which can result in costly downtimes and equipment damage. For companies using bearings in harsh conditions, such as factories or production plants, proper lubrication is critical. Below are practical tips and common issues related to bearing lubrication.

Common Bearing Lubrication Problems

Inadequate Lubrication

One of the most common issues maintenance teams face is under-lubrication. Bearings that don’t receive enough lubrication are prone to increased friction, leading to overheating and excessive wear. To prevent this, it is essential to consider the following factors:

• Viscosity: The viscosity of the lubricant is crucial, as it affects the formation of a lubricating film between the rolling elements. Bearings operating in high-temperature conditions require lubricants with higher viscosity to withstand extreme thermal conditions.

• Operating Temperature: Lubricants need to be resistant to high or low temperatures. For example, lithium-based greases are used for low temperatures, while synthetic lubricants are preferred for high-temperature applications.

• Load Conditions: Heavily loaded bearings need greases with EP (extreme pressure) additives, which improve the grease's ability to withstand heavy loads without degradation.

How to Properly Relubricate Bearings

• Maintain Proper Grease Quantity: Avoid over-lubrication, as excess grease can lead to a phenomenon called "churning," causing temperature rise and faster grease degradation. Typically, it’s recommended to fill the bearing cavity to one-third of its internal volume.

• Regular Relubrication Schedule: Establish a lubrication schedule based on operational hours and environmental conditions. In harsher environments (e.g., high temperatures, contamination), some machines may require more frequent relubrication.

• Relubrication Techniques: The best method for lubrication is using automatic systems, which deliver the correct amount of grease at regular intervals, helping avoid errors caused by over- or under-lubrication.

• Monitoring: Regularly monitoring bearing temperature and noise can indicate when relubrication is needed. Installing temperature and vibration sensors can help detect problems early on.

Recommendations

• Lubricant viscosity should match the bearing’s operating temperature.
• Regular relubrication according to a schedule is key to optimal performance.
• Automatic lubrication systems help maintain proper lubrication levels and reduce errors from manual methods.

Over-Lubrication of Bearings – Causes, Effects, and Prevention

Over-lubrication can be as harmful as under-lubrication. While it may seem like more grease offers better protection, excess grease can cause operational and mechanical problems.

Causes of Over-Lubrication

Over-lubrication often occurs due to errors made during manual lubrication. Common causes include:

• Lack of Clear Lubrication Procedures: When personnel lack defined guidelines, they may assume more grease equates to better lubrication.

• Improper Use of Grease Guns: Grease guns can deliver large amounts of grease at high pressure, which can lead to overfilling the bearing.

• Lack of Monitoring: Manual lubrication without regular monitoring of bearing temperature and vibration levels increases the risk of over-lubrication.

Effects of Over-Lubrication

• Churning of Grease: Excessive grease leads to churning, where rolling elements must push through the excess, increasing friction. This results in:

  • Temperature Rise: Increased friction raises the operating temperature of the bearing, leading to faster grease breakdown. High temperatures can soften or even melt the grease, reducing its effectiveness.
  • Reduced Grease Life: Over-greased bearings working at higher temperatures lose their lubrication properties more quickly, requiring frequent relubrication.

• Seal Damage: Excessive grease creates internal pressure, which can force grease out through the seals. When seals are damaged:

  • Contaminants Enter the Bearing: External contaminants like dirt or moisture can enter the bearing, causing corrosion, wear, and eventual failure.
  • Grease Leakage: Damaged seals lead to grease leakage, reducing lubrication efficiency and causing mechanical damage.

• Inefficient Bearing Performance: Over-greasing increases the load on bearings, leading to faster wear. Instead of moving smoothly, rolling elements must overcome greater resistance, reducing the bearing’s efficiency and accelerating component wear.

When Does Over-Lubrication Occur?

Over-lubrication is most likely to occur in situations where:

• Bearings are lubricated too frequently: Without a defined lubrication schedule, unnecessary frequent lubrication causes grease to accumulate inside the bearing.
• Manual lubrication methods are used without control: Automated systems deliver precise amounts of grease, while manual methods, especially without supervision, often lead to excess grease.

How to Prevent Over-Lubrication

• Set a Precise Lubrication Schedule: Develop a regular schedule that defines the exact intervals and amounts of grease needed to prevent over-lubrication.

• Use Automatic Lubrication Systems: Automated systems provide the right amount of grease, reducing the risk of excess. Regularly check grease levels and monitor bearing temperature and vibrations to prevent issues.

• Monitor Temperature and Vibrations: Installing temperature and vibration sensors in bearings helps detect lubrication-related issues early, preventing overheating and mechanical failure.

Contamination of Grease

Contaminated grease significantly impacts bearing performance and longevity. Particles such as dirt, dust, water, or chemicals can infiltrate the bearing system if lubrication points are poorly sealed, or if contaminated grease is used during relubrication. These contaminants accelerate bearing wear, leading to costly repairs or equipment replacement.

Incorrect Grease Selection

Not all greases are suitable for every bearing. It is essential to choose the right grease for the bearing’s operating conditions, including:

• Temperature: High-temperature applications require synthetic greases, while low temperatures call for lithium-based greases.

• Load Conditions: Heavily loaded bearings need EP additives to enhance the grease's durability under pressure.

• Speed: High-speed bearings need low-viscosity greases, while low-speed bearings benefit from higher-viscosity greases.

Best Practices for Bearing Lubrication

• Regular Lubrication Schedule: Establish consistent intervals based on the manufacturer’s guidelines and operational needs. Regular monitoring helps avoid over- and under-lubrication.

• Automatic Lubrication Systems: For critical machinery or inaccessible areas, automatic lubrication systems ensure the right amount of grease is applied at optimal intervals, reducing human error.

• Monitor Bearing Temperature and Noise: An increase in temperature or unusual noises can indicate improper lubrication. Installing temperature and vibration monitoring tools helps detect issues early.

Conclusion

Proper lubrication is key to maximizing bearing life and performance in harsh environments. Avoid common pitfalls such as over-lubrication, contamination, and incorrect grease selection. Investing in the right lubricants and lubrication practices will improve equipment reliability, reduce costs, and prevent downtime.

At Simmering.pl, you can find a wide range of bearings and radial oil seals designed for tough industrial applications. Proper lubrication is essential for getting the most out of these products, so explore our offerings to find the best solutions for your industrial needs.