Carbon brush blanks are the basic materials for manufacturing carbon brushes used in motors, generators, and other equipment. Their performance directly determines the conductivity, wear resistance, lubrication, and service life of the carbon brushes. Based on the raw material composition, manufacturing process, and application scenarios, carbon brush blanks are mainly divided into the following categories:

1. Graphite Carbon Brush Blanks

Raw material composition: Made from natural or artificial graphite as the main raw material, processed through crushing, molding, and firing. Some may contain a small amount of binder (such as asphalt or resin).

Performance characteristics: Soft texture, good self-lubrication, low friction coefficient, and minimal wear on the commutator; excellent conductivity and reduced contact voltage. The disadvantage is relatively weak mechanical strength and poor impact resistance.

Applicable scenarios: Suitable for low-load, low-speed DC motors, such as household appliance motors and small power tool motors.

2. Electrographite Carbon Brush Blanks

Raw material composition: Made from graphite and coke as raw materials, molded with a binder, then subjected to high-temperature firing, followed by graphitization treatment at 2000-3000℃.

Performance characteristics: Compared with ordinary graphite blanks, it has higher crystallinity, better conductivity and thermal conductivity, and significantly improved wear resistance and high-temperature resistance; stable friction coefficient, excellent commutation performance, and reduced spark generation.

Applicable scenarios: This is the most widely used type of carbon brush blank, suitable for medium-to-high load DC motors, traction motors, and generators, such as automotive starter motors, industrial motors, and locomotive traction motors.

3. Metal Graphite Carbon Brush Blanks

Raw material composition: Based on graphite, mixed with metal powders such as copper, silver, tin, and lead (metal content usually ranges from 10% to 90%), then mixed, pressed, and sintered.

Performance characteristics: Conductivity is far superior to pure graphite blanks (the higher the metal content, the better the conductivity); high mechanical strength and strong impact resistance; good wear resistance, but slightly higher wear on the commutator than pure graphite blanks. Subdivision of Types and Applicable Scenarios

Copper-Graphite Blanks: Copper content 30%~80%, good conductivity, moderate cost, suitable for high-current, low-voltage motors, such as battery-powered locomotives and forklift motors.

Silver-Graphite Blanks: Silver content 10%~30%, excellent conductivity, corrosion resistance, suitable for high-precision, high-demand motors, such as aerospace motors and precision instrument motors.

Lead-Graphite Blanks: Lead powder is added to improve lubrication, suitable for low-speed, heavy-load motors.

4. Resin-Bonded Carbon Brush Blanks

Material Composition: Graphite powder is used as the aggregate, and organic resins such as phenolic resin are used as binders.  They are manufactured through pressing and curing, without high-temperature firing.

Performance Characteristics: High mechanical strength, good processing performance, and can be made into complex shapes; slightly better insulation than graphite blanks, stable friction coefficient, but poor high-temperature resistance (resin is easily carbonized).

Applicable Scenarios: Suitable for low-to-medium temperature, low-load small motors, such as miniature DC motors and electric toy motors.

5. Carbon Fiber Reinforced Carbon Brush Blanks

Material Composition: Carbon fibers are added to the graphite matrix as a reinforcing phase to improve the mechanical properties of the blank.

Performance Characteristics: Extremely high mechanical strength and wear resistance, strong impact and fracture resistance; excellent conductivity and thermal conductivity, outstanding high-temperature resistance.

Applicable Scenarios: Suitable for high-speed, high-load, high-temperature harsh working condition motors, such as aero engines and high-power industrial generators and other high-end equipment.