Lubrication Methods for Linear Ball Screws

Linear ball screw is a high-precision moving element widely used in mechanical transmission systems. During its operation, lubrication is an important factor to ensure its normal operation and extend its service life.

1. Lubrication Method

The lubrication method of linear ball screw pair is the same as that of rolling bearing. It can be lubricated with either oil or grease. If the lubrication amount of ball screw is too little, lubrication will be interrupted, and if it is too much, it will cause heat and increase resistance. Therefore, the appropriate lubrication amount must be selected according to the use conditions.
Note: When using grease to lubricate the ball screw, the old grease on the screw should be thoroughly cleaned before filling. Please avoid mixing lubricants with different properties.

1.1 Lubricating Oil

The lubricating oil is sprayed between the linear ball screw and the guide rail through the oil circuit to form a thin film to reduce friction and wear. Oil lubrication is suitable for high-speed, high-load and high-precision screws.
The following table shows the approximate standard of lubricating oil filling amount. However, it will vary according to the stroke, type of lubricating oil, and use conditions (suppressing heat generation).

1.2 Grease

Apply grease to the surface of the linear ball screw and guide rail to form a lubricating film to reduce friction and wear. Grease lubrication is suitable for low-speed, low-load and low-precision screws.
The amount of grease required is generally about one-third of the internal space volume of the nut.

2. Lubrication Type Selection

Choosing the right lubricant is crucial to the performance of the linear ball screw. The following are several factors to consider when selecting lubricants:

2.1 Screw Running Speed

The running speed is one of the important factors affecting the selection of linear ball screw lubrication methods. Different lubrication methods perform differently at different speeds.
Low-speed operation: For low-speed and heavy-loaded ball screws, grease is more suitable because it has a higher viscosity and can provide better sealing and lubrication performance.
High-speed operation: For high-speed and high-precision linear ball screws, liquid oil is usually the first choice because it can provide better lubrication and heat dissipation performance.

2.2 Working Environment Temperature

Low-temperature environment: Choose a lubricant with good low-temperature fluidity, because grease is easy to harden in a low-temperature environment, making it difficult for the screw to run.
High temperature environment: Choose grease with high temperature stability to avoid grease loss or oxidation due to temperature rise.

2.3 Load

Light load: It is recommended to use low viscosity grease to reduce friction resistance and heat generation.
Heavy load: Oil lubrication is preferred, and high viscosity lubricant is used to ensure good lubrication performance.

3. Storage

The linear ball screw is a precision mechanical component and should be avoided from impact during transportation or other situations. After taking it out of the transport packaging box, the screw should be placed horizontally on a wooden or plastic bracket. The protective cover outside the screw packaging can only be removed when the ball screw is installed. If the screw is to be stored for a long time, the screw should be hung vertically to prevent the screw from bending due to its own weight.

4. Installation

1. The axis of the screw must be parallel to the axis of the matching guide rail. When the nut is connected to the nut seat, try to get close to the support bearing; similarly, when installing the support bearing, try to get close to the nut installation part.
2. For dual-drive ball screws, the two ball screw bodies must be parallel during installation, and the two nuts must be evenly stressed without any eccentric load, otherwise the ball screw will wear out too quickly.

Summary

The lubrication method of the linear ball screw has an important impact on its performance and service life. By reasonably selecting the lubrication method and lubrication materials, and performing regular lubrication maintenance, the working efficiency and reliability of the ball screw can be effectively improved.