Carbon Brushes

Efficient Power Transmission with Carbon-Based Brushes

High-quality carbon brushes ensure smooth operation of industrial systems and household appliances alike. As sliding contacts, they are essential for safe and efficient electrical current transfer between stationary and moving components – used in everything from power tools and dryers to steel mills, wind turbines, and hydropower generators. Discover the customizable carbon brushes from Schunk Group – small components with a major impact on the performance and reliability of electric motors.

Carbon Brush Configurator

Carbon Brushes

Small Components, Big Tasks

Given the wide range of applications, there is also a wide variety of carbon brushes. Below are some of the key factors that influence brush design.

Factors that influence brush geometry and dimensions include:

Available installation space
Electrical design (current load, power rating)
Mechanical requirements (contact pressure, vibrations, commutator roundness)
Legacy design (previous equipment layout)
Cost-effective manufacturing (especially when manufacturers are involved early in the design phase)

The Material

Material selection is typically a multi-stage process that ends with service life testing. A layperson might choose a material solely based on hardness or resistance values – but in practice, many additional factors must be considered. Experience and knowledge of the application help narrow down the vast range of materials to the most promising candidates.

Additional factors influencing material selection include:

Electrical characteristics of the motor
Motor speed
Environmental conditions (dust, humidity, surrounding media, temperature)
Commutator material
Application temperature
Intensity of vibration
EMI/EMC requirements
Cost
Production volume

The Brush Surface – Contact with the Commutator

The brush contact surface can be optimized with features such as pre-formed radius, grooves, or specific impregnation treatments to ensure fast and reliable motor break-in. This minimizes the risk of damage, premature wear, and long conditioning times.

Electrical Connection of the Brush

In the simplest case, the current is transferred via the spring in the brush holder. However, the spring may soften under high current, reducing contact pressure. The most common design uses embedded copper leads (pigtails) to carry the current independently. These leads can handle significantly higher currents than springs. Depending on current requirements and brush type, multiple pigtails may be used. Leads can be supplied with or without connectors, usually crimped. Soldered or welded connections are also possible depending on material compatibility.

Optional Brush Features

Wear indicator: Sends a signal via a separate line when the brush has reached a defined wear limit – allowing timely replacement.
Cut-off device: Automatically lifts the brush off the commutator when the wear limit is reached, interrupting the current flow and protecting the commutator from damage caused by exposed leads or insufficient contact pressure.
Damping device: A silicone layer at the brush head dampens vibration between brush and commutator, reducing brush arcing, wear, and potential commutator damage.

Electric Motors: Custom Solutions for a Wide Range of Requirements

Carbon brushes for electric motors must meet many specific requirements – from high speeds and variable loads to harsh environments. The key is carefully matching material, geometry, and impregnation to ensure long-term efficiency, service life, and reliability in industrial, household, or niche applications.

Carbon Brushes for Electric Motors

Slip Ring Applications: Reliable Performance in Extreme Conditions

Certain slip ring applications demand highly specialized brush designs – especially where signal or power transfer must remain reliable in harsh conditions. From medical systems and industrial plants to marine environments, material combinations, impregnation treatments, and precise construction ensure smooth, long-term operation.

Carbon Brushes Slip Ring Applications

Generators: Brushes for Demanding Rotating Systems

Generators require brushes that can withstand long runtimes, continuous energy transfer, and thermal and mechanical stresses. Whether in power plants, wind turbines, or compact turbo-generators, brush systems must be fine-tuned to the specific operating environment.

Carbon Brushes for Generators

Special Applications: Brushes for Unique Use Cases

In technical niche markets, carbon brushes remain indispensable – even if their presence is hidden. Where precision, material compatibility, or resistance is critical, selecting the right material is key to ensuring reliable performance under specialized technical conditions.

Carbon Brushes for Special Applications

Proven millions of times over

Solutions for DC Drives, Signal Transmission, Slip Ring Applications, Household Appliances, Power Tools and Wind Turbines

From Household Appliances to Wind Turbines

The many years of experience of our experts and our internationally oriented corporate structure make us a competent partner for many manufacturers of electric motors for power tools and household appliances as well as for the railroad, automotive and wind power industries. Whether carbon brushes, brush holders, carbon brush monitoring, contacts, shaft grounding or carbon fiber-based components for shaft grounding - our approach to finding solutions is convincing thanks to our high level of innovation and intensive development consulting. To this end, we have a wide range of material and solution variants available in terms of additional treatments and features, geometries and electrical contacting. Our own professional test laboratory is another building block that enables our consistently high manufacturing quality. Take our micro-carbon brushes as an example: Even these tiny ones with a volume of a few cubic millimeters are full of convincing properties - a perfect balance of transition stress, coefficient of friction, Rockwell hardness, bending strength, raw density, metal content and other parameters.

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