Silicone grease for actuator assemblies
Silicone grease maintains a stable viscosity across a temperature range of -40°C to 200°C, making it a suitable choice for automotive actuator assemblies such as mirror folding, power seat adjustment and window regulators. This article explains why and how to choose the right grease.
Actuator assemblies typically consist of a small motor, plastic gears and metal shafts. They must operate smoothly and quietly and maintain a stable operating force throughout the vehicle's life, from freezing winters to parking under scorching sun.
Why choose silicone grease
Silicone base oils have a very high viscosity index, meaning their viscosity changes little with temperature. At -40°C, conventional mineral greases can thicken and overload the motor, while silicone grease remains soft enough for the mechanism to operate. Silicone is also highly compatible with most plastics and rubbers, causing no swelling or stress cracking.
Comparison with other greases
| Grease type | Temperature range | Plastic compatibility | Load-carrying capacity |
|---|---|---|---|
| Lithium mineral grease | -20 to 120°C | Moderate | Good |
| PAO synthetic grease | -40 to 150°C | Good | Good |
| Silicone grease | -40 to 200°C | Excellent | Moderate |
| Fluorosilicone grease | -40 to 230°C | Excellent | Fairly good, fuel resistant |
Typical applications
- Plastic gears in side mirror folding motors.
- Slide rails and lead screws in power seat adjusters.
- Window rubber seals, reducing friction and squeaking.
- Dashboard switches and rotary knobs for a smooth tactile feel.
Usage notes
Silicone grease has a lower load-carrying capacity than mineral-based grease and should not be used on heavily loaded metal gears. In addition, silicone grease must not contaminate surfaces that will be painted or bonded, as silicone sharply reduces adhesion. On the production line, the greasing area should be kept separate and metering equipment used to control the amount of grease.
When evaluating a grease for a new mechanism, engineers should run the mechanism at the lowest and highest required temperatures, measure motor current and noise level, and check whether the grease separates oil or migrates out of the lubricated zone after thermal testing. Compatibility testing, by immersing plastic parts in grease at 80°C and then checking changes in weight and tensile strength, is also a necessary step, especially for POM and PA plastics commonly used for gears.
The grease is available in a range of pack sizes, from small tubes for repair shops to large drums for automatic dispensing machines.
To choose the right silicone grease for your mechanism, please contact AMS Vietnam.
