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Keep your bearings

Top 5 causes of bearing failures in vessels

On ships, roller bearings are typically deployed in electric motors, reduction gearboxes, and thrusters. But as these machines are often difficult to access, repairing or replacing damaged bearings can be a time-consuming and costly endeavor. Here are the five most common causes of bearing failures and how to prevent them.

1. Electrical damage

Electrical damage, also known as fluting or arcing, can happen when a current passes from one ring to the other through the rolling elements. These stray currents can cause pitting damage to the rolling elements and raceways of the bearing, shortening the bearing’s service life. Another possible consequence is accelerated degradation of the lubricant, causing premature failure.

Insulated or hybrid bearings can reduce the risk of electrical arcing. Ceramic coatings applied to the steel surface offer reliable protection against stray currents and damages. Such solutions can also prove more cost-effective than insulating the housing or the shaft.

2. Inadequate lubrication and contamination

Lubrication is one of the most important factors in bearing life. But if the lubricant is contaminated by foreign particles or water, or the lubrication film is too thin, metal-to-metal contact will occur, increasing wear on the bearing.

To resolve this, you should check that you are using the correct lubricant—in some cases, you may need to use a lubricant with a higher viscosity. You should also ensure that re-greasing intervals are frequent enough for the application. Automatic lubrication systems are one solution to this issue. In the case of oil lubrication, effective filtering and dewatering systems will contribute to keeping the oil in good operational condition. If the lubricant contains contaminants, you will need to examine your seals—they might need replacing or upgrading.

3. Vibration

All machinery aboard vessels is exposed to vibrations. However, if these vibrations increase, for example due to shaft misalignment, then they can damage the bearings raceway surfaces. Even if the machinery is at a standstill, external vibrations can have a negative effect on bearing life.

One way to prevent vibration damage is to ensure optimal shaft alignment and stable machine foundations.

4. Improper installation and set-up

Common installation mistakes, such as misalignment, imbalance, or incorrect mounting, can overload the bearing. This can lead to several types of damage, including brinelling, which is when the bearing’s surface develops permanent indentations. For this reason, it is important to use precision instruments when installing and mounting bearings. Shaft alignment tools and vibration analysis solutions help ensure proper installation and reliable Operation.

5. Insufficient load
Bearings always need to have a minimum load to function well and ensure rolling elements do actually roll. If the external load is insufficient, this can lead to smearing, where material is transferred from one surface to the other. This damages the raceways and rolling elements, eventually resulting in premature failure.
To combat this, it is important to apply sufficient load and proper lubrication. Preloaded bearings also provide an effective solution.

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