Grease Filling Method for Cylindrical Roller Bearings in Main Shaft Bearings

Grease Filling Method for Cylindrical Roller Bearings in Main Shaft Bearings

The spindle bearings of machine tools are the main shaft bearings of precision machine tools and similar equipment, which are crucial for ensuring the working accuracy and performance of precision machine tools. Functionally and structurally, spindle bearings can be divided into two major categories: rolling bearings and sliding bearings.

(1) Apply 80% of the filling amount of grease evenly on the rolling surfaces of the rollers. At this time, it is recommended that not too much grease be applied to the inner side of the cage. The grease on the inner side of the cage is difficult to spread during the initial running-in stage, which will increase the temperature rise and also prolong the running-in time.

(2) The grease on the roller raceway surface will spread to the end faces of the rollers, the contact parts between the cage and the rollers, and the entrances of the pockets, so that the grease is evenly distributed throughout the bearing.

(3) Apply 20% of the filling amount of grease evenly and thinly on the outer ring raceway surface that will be installed into the bearing housing.

Whether the bearings are installed correctly directly affects the accuracy, life, and performance of the bearings. Therefore, it is hoped that the design and installation departments will fully discuss the installation of bearings and carry out the installation in accordance with the operation standards. The items of the operation standards are as follows:

Cleaning of Bearings

To prevent dust and rust during transportation and storage, anti-rust oil is applied to the surface of the bearings when the products are shipped. After unpacking, the anti-rust oil should be cleaned off first. (Bearings that have been filled with grease or equipped with sealing rings do not need to be cleaned.)

1) Generally, kerosene or gasoline is used as the cleaning fluid for bearings.

2) Separate the cleaning tank into a rough cleaning tank and a fine cleaning tank, and place metal nets at the bottoms of the tanks respectively so that the bearings do not directly contact the dirt in the cleaning tank.

3) In the rough cleaning tank, try to avoid rotating the bearings. After roughly removing the dirt attached to the surface of the bearings with a brush or the like, place them in the fine cleaning tank.

4) In the fine cleaning tank, gently rotate the bearings for cleaning. The cleaning oil in the fine cleaning tank must be kept clean at all times.

5) After cleaning, carry out degreasing. If it is grease, perform the work of filling grease. If it is oil-air lubrication, install the bearings onto the main shaft as far as possible when the bearings are not rotating. (At this time, it will have a better effect if a thin layer of lubricating oil is applied to the surface and inside of the bearings.)

Inspection of the Dimensions of Related Components

1) Inspection of the Shaft and the Bearing Housing

a. The shaft and the bearing housing should be cleaned thoroughly. Scratches, burrs, flash, etc. are not allowed on the surfaces of the bearings and spacer rings.

b. Check the dimensions of the shaft and the bearing housing to confirm whether they conform to the tolerance fits with the inner and outer diameters of the bearings.

c. Measurements (including installation) should be carried out in a constant temperature room. When the temperature of the object to be measured is in a stable state, use a micrometer or an internal diameter dial indicator for measurement. (Multiple-point measurements must be carried out to check for obvious dimensional differences.)

2) Inspection of the Spacer Rings

The parallelism of the spacer rings configured on the main shaft should be controlled below 0.003 mm. Poor parallelism of the spacer rings will cause the bearings to tilt, resulting in problems such as poor accuracy and noise. 

By following these steps, you can effectively find and use interchangeable bearings for your applications. If you have a specific bearing in mind that you need to interchange, let me know, and I can help further!