Lubricating a bearing is an essential operation in the maintenance of mechanical equipment. But this seemingly innocuous step is complex and should not be overlooked. It's important to ask the right questions in order to optimize this process. We'll explore the 4 fundamental pillars to examine before lubricating a bearing. This will help you make the right choices to optimize the life of your machines.

Which lubricant to choose ?

There are a multitude of greases and lubricants for different applications. The choice of lubricant will be determined by a number of factors.

Most bearings are lubricated with grease. To determine which type of grease to use, you need to take into account the different characteristics of your part.

• Operating temperature
• Applied load
• Rotation speed
• Axis direction (horizontal or vertical)

Oils

Suitable for high speeds and low to medium temperatures. They are often used in circulation systems or with oil baths.

Example : OIL-ALL-OIL-AEROSOL-200ML-3ENUN

Greases

More practical for applications where maintenance is more difficult. It will stay in place longer and offer better protection against contaminants.

Example : GEAR GREASE-LGMT2-35G-SKF

Most grease and bearing manufacturers provide their customers with grease classifications. These can be used to make an initial selection based on temperature, load and speed.

Link to SKF, NTN and FAG tables

Oil lubrication is less common, but is still used in a number of situations :

• Plummer block housings with oil bath
• Gearbox housings
• Bearing housings with oil recirculation
• Air/oil spray systems for machine-tool spindles

Oils can be mineral or synthetic, with additives.

How much lubricant should I use ?

Too little or too much lubrication can be detrimental to a bearing and its service life. As a general rule, a bearing should be 100% filled, but there are certain exceptions: depending on speed and process temperature, the housing can be filled to between 40% and 60%.

When topping up, the quantities of grease to be added will vary according to various criteria :

• Bearing type (dimensions, cage)
• Grease entry point
• Lubrication mode (automatic or manual)

To determine the quantity of grease to be used for a bearing, you can refer to the (free) calculation programs offered by manufacturers.

• SKF calculation program
• Schaeffler's Grease app

When to lubricate a bearing ?

How often a bearing needs to be lubricated depends on a number of factors :

• Temperature
• Load
• Rotation speed
• Level of contamination
• Bearing size and type
• Vibration

To find out at what intervals to grease your bearings, it's always best to refer to the methods explained on manufacturers' websites.

What to do ?

Manual or automatic, how do you decide and make the right choice ?

In most cases, you can use either method without worry.

The advantages of automatic lubrication :

• No constant monitoring
• Promotes thermal balance
• Top-up can be modulated for more continuous distribution

Manual lubrication :

• Allows a series of other checks (vibration, noise, temperature, etc.) to be carried out at the same time.
• Relubrication can be adapted directly to unexpected events: changes in temperature or speed, unforeseen contamination, etc.

Asking the right questions before lubricating a bearing is crucial to optimizing the maintenance and performance of your equipment. By determining the right type of lubricant, the frequency of lubrication required, the most effective method, and the exact quantity to apply, you'll not only extend the life of your bearings, but also keep your machines in optimum operating condition. Never forget that every detail counts when it comes to bearing lubrication, and that the care you take today can save you complications and expense tomorrow.