How to Determine Lubrication Frequency in Bearings

We continue our series titled "Lubrication Management"...

In my previous articles, I tried to answer the questions "Which" and "How much". You can find detailed explanations on these topics in the articles titled "How to Choose the Right Oil for Bearings" and "How to Determine the Right Amount of Oil for Bearings".

In this article, I will try to answer the question "At what frequency?".

Last December, you updated your maintenance plans for this year. In your plan for 2025, you had planned the lubrication periods for all lubrication points in one-month and three-month cycles. However, you are aware that this is increasing your workload. The amount of oil you use has also increased by approximately 2 times compared to before. This may seem positive on the surface.

However, you are still seeing lubrication problems in the bearings you have replaced due to failures. Increasing the lubrication frequency will further increase your workload, and the planned maintenance you cannot complete will reduce your planned maintenance completion rate target.

So what should be done…

If we approach this problem from a Reliability-Centered Maintenance perspective, we can find many solutions, but right now our focus will be on determining the lubrication frequency.

F = Lubrication Frequency (hours)

n = Rotational Speed ​​(rpm)

D = Shaft Diameter (mm)

K = Bearing constant (Ball Bearing = 10, Cylindrical Bearing = 5, Spherical Bearing = 1, Tapered Bearing = 1)

The formula above will give you the most accurate result because it is effective for bearings subjected to heavy loads and axial loads.

However, this calculation method does not take into account the bearing's operating conditions and the environmental factors it is exposed to.

For such demanding conditions, the guidelines in the table should be considered when determining the lubrication frequency.

Exposure	Change in Frequency
Working Temperature	In working conditions above 65°C, the temperature should be halved for every 4°C.
Moisture Exposure	Depending on the severity of moisture exposure, you can increase the frequency by up to 95%.
Dirtiness	Depending on the type of dust it's exposed to, you can increase the frequency by up to 70%.
Bearing Location	For bearings on a vertical shaft, you can increase the frequency by up to 50%.
Vibration	Depending on the intensity of the vibration it is exposed to, you can increase the frequency by 1/3.