Do new bearings require grease? A Comprehensive Guide to Bearing Lubrication and Main

In the operation of industrial equipment, bearings play a vital role. Many users often wonder when replacing new bearings: do new bearings need to be greased? Improper lubrication may lead to shortened bearing life, frequent equipment failures, and even downtime losses. This article will analyze in detail whether new bearings need to be lubricated, as well as lubrication precautions under different working conditions.

I. Are new bearings pre-greased at the factory?

In most cases, new bearings are pre-filled with suitable grease at the factory. These products are called “pre-lubricated bearings.” For example, common deep groove ball bearings, self-aligning ball bearings, and pillow block bearings are usually filled with a certain proportion of grease and sealed with dust covers or shields. This means users can install them directly without adding additional grease.

However, not all new bearings contain grease. For some open-type bearings or those used in special conditions (such as high temperature, high speed, or vacuum environments), they are usually not pre-filled with grease, and users need to select lubrication according to the specific application.

II. Criteria for determining whether new bearings need greasing

To determine whether a new bearing needs greasing, consider the following aspects:

2.1, Whether it is a sealed bearing

Bearings with shields or seals (such as ZZ, 2RS types) are usually pre-filled with grease and do not require additional lubrication. Open bearings must be greased before installation, otherwise they will be quickly damaged due to dry friction.

2.2, Operating conditions of the equipment

2.3, Manufacturer’s technical documents

Before installation, check the product manual provided by the bearing manufacturer. If it clearly states “pre-filled with grease,” the bearing can be installed directly. If it requires user greasing, follow the recommended method.

III. Bearing grease selection and application methods

3.1, Selection of grease

Common bearing greases include lithium-based grease, calcium-based grease, high-temperature grease, low-temperature grease, and synthetic grease. When choosing, consider the operating temperature range, speed rating, load size, and working environment.

3.2, Control of grease amount

Generally, the grease filling amount should be 30%-50% of the bearing internal free space. Too much grease may cause overheating and increased stirring resistance, reducing bearing life. Too little grease may cause insufficient lubrication, leading to premature wear.

3.3, Greasing methods

Use professional grease guns or injection tools to inject grease from the side of the bearing or through the lubrication hole. Maintain cleanliness and avoid dust or impurities entering the bearing. For critical equipment, a regular greasing and grease replacement plan should be established.

IV. Practical applications in the industrial field

In industries such as machinery manufacturing, wind power, metallurgy, and textile machinery, newly installed bearings often suffer from abnormal noise, overheating, or poor operation if not properly lubricated. Many enterprises’ experience shows:

Sealed new bearings can be used directly, but lubrication should be checked periodically after long operation;

Open-type new bearings must be greased, especially in dusty, humid, or high-temperature environments, where lubrication is even more critical;

High-end equipment (such as precision machine tool spindles) requires special lubricants and may even use oil-air or circulating lubrication systems.

V. Conclusion: Do new bearings need greasing?

In summary, whether a new bearing needs greasing depends on its structure and application environment:

Proper lubrication is the key to extending bearing life and ensuring stable equipment operation. For industrial users, understanding the necessity, methods, and intervals of bearing lubrication can not only reduce maintenance costs but also improve production efficiency.