I. Selection of Silicone Oil Type

1. Dimethyl silicone oil (methyl silicone oil)
   Dimethyl silicone oil becomes the first choice for carbon brushes due to its excellent comprehensive performance:

• High temperature resistance: It can work stably for a long time at -50℃ to 200℃, adapting to the high-temperature environment when the motor is running.
• Low friction coefficient: It can significantly reduce the wear between the carbon brush and the commutator, extending the service life of components.
• High insulation: It has low dielectric loss, resistance to arc and corona, ensuring stable electrical performance of the motor.
• Chemical stability: It is resistant to acids, alkalis and oxidation, reducing corrosion on the carbon brush surface.
• Low volatility: It has small evaporation loss and can maintain the lubrication effect for a long time.

2. Limitations of fluorinated silicone oil
   Although fluorinated silicone oil has high temperature resistance (up to 280℃) and chemical corrosion resistance, its cost is relatively high, and it is rarely used in carbon brushes. Currently, mainstream carbon brushes still mainly use dimethyl silicone oil.

II. Basis for Viscosity Selection

1. Versatility of 100 mm²/s (cSt)

• Patent verification: In the carbon brush impregnation process, dimethyl silicone oil with a viscosity of 100 mm²/s is clearly used to improve sliding performance and reduce contact resistance.
• Industry practice: Precision carbon brush oil (such as DERILL ME38-D1) does not directly mark the viscosity, but it is designed for micro-motors with low current and low contact pressure, which is consistent with the recommended range of 100 mm²/s.
• Balance between lubrication and heat dissipation: This viscosity can not only form a stable oil film but also effectively dissipate heat, avoiding performance degradation caused by high temperature.

2. Application scenarios of other viscosities

• Low viscosity (e.g., 50 mm²/s): Suitable for occasions requiring rapid penetration, but may lead to insufficient lubrication due to the thin oil film.
• High viscosity (e.g., 350 mm²/s): It can provide stronger adhesion, but may increase the operating resistance of the motor, so adjustments need to be made according to specific requirements.

III. Key Performance Requirements and Additives

1. Base oil performance

• It needs to meet the requirements of low volatility, high flash point (≥315℃) and high shear resistance (more than 20 times better than mineral oil).
• For example, Methyl Silicone Oil 201-100 has a flash point of 188℃ and a kinematic viscosity of 100 mm²/s, which meets the requirements of most motor carbon brushes.

2. Function of additives

• Antioxidant: Prevents the silicone oil from oxidizing and deteriorating at high temperatures, extending its service life.
• Anti-corrosive agent: Protects the commutator (e.g., copper material) from electrochemical corrosion.
• Conductivity enhancer: Some carbon brush oils improve conductivity by adding metal compounds (such as nano-nickel powder).

IV. Application Process and Precautions

1. Impregnation process

• Immerse the carbon brush base material in a silicone oil solution (usually with a concentration of 1-80%) and impregnate it at 60℃ for 15-30 minutes, then dry it to remove moisture.
• The impregnation rate is controlled at a weight ratio of 0.2-10% to ensure the uniform distribution of silicone oil in the carbon brush pores.

2. Compatibility test

• It is necessary to verify the compatibility of the silicone oil with carbon brush materials (such as graphite, resin) and other motor components (such as seals) to avoid material swelling or embrittlement.

3. Environmental adaptability

• In low-temperature environments, silicone oil with a slightly lower viscosity (e.g., 50 mm²/s) can be selected to ensure fluidity; in high-temperature environments, priority should be given to high-viscosity silicone oil or fluorinated silicone oil.

V. Reference for Typical Products

1. DERILL ME38-D1 Precision Carbon Brush Oil

• It is compounded by high-performance synthetic oil (presumably dimethyl silicone oil) and additives, suitable for the lubrication and protection of micro-motor carbon brushes, and can stabilize current and reduce noise.

2. Methyl Silicone Oil 201-100

• With a kinematic viscosity of 100 mm²/s and a flash point of 188℃, it is widely used in motor carbon brushes, insulation impregnation and high-temperature lubrication.

Summary

Dimethyl silicone oil (methyl silicone oil) with a viscosity of 100 mm²/s is an ideal choice for motor carbon brushes, as it exhibits excellent comprehensive performance (high temperature resistance, low friction, high insulation) and cost-effectiveness. In practical applications, it is necessary to select the appropriate silicone oil model and impregnation process based on the motor type, operating environment and process requirements to achieve the best effects of lubrication, heat dissipation and wear resistance.

The content of this article is assisted by intelligent technology, and proofread and edited by the dedicated editorial team. If there are any omissions or errors, please feel free to inform us via private message. We will verify and correct it promptly, and jointly maintain the accuracy and value of the information.