Do you supply carbon-graphite contacts?

Yes. We supply carbon-graphite materials and formats (bars, machined parts) for pantographs, electrical contacts, and grounding, graded by current, speed, and environment.

Why are sliding contacts made of carbon rather than metal?

Because the contact must conduct and slide without a lubricant. A metal-on-metal contact welds or wears the counterface; carbon self-lubricates, forms a stable film, and is consumed instead of the commutator or wire.

What role does the contact film play?

It is the layer formed on the counterface during running-in that stabilizes both friction and voltage drop. When the environment prevents it forming — with vapours or abrasives, for example — wear increases markedly.

How is the grade selected?

On current density, sliding speed, and contact pressure, plus the working environment. These define the trade-off between resistivity and wear resistance; values per grade are published.

Can contacts be made from a used part?

Yes. From the part or drawing the geometry is reproduced — including chamfers, cable seating, and contact-face radius — and an equivalent grade proposed.

Electrical applications

Electrical contacts

Improves electrical conductivity and reduces wear in electrical contact systems.

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Sliding electrical contact

Also known as: Carbon brushes · Carbon-graphite contacts · Pantograph contact strips · Graphite sliding contacts

[ Technical summary ]

A sliding electrical contact must carry current while rubbing against a moving part — commutator, slip ring, or contact wire — without wearing the counterface. Carbon and carbon-graphite meet that dual demand because they conduct reasonably and self-lubricate, forming a film that stabilizes the contact. The cheaper element of the pair is sacrificed in a controlled way, protecting the commutator or wire, which is the costly part of the system.

[ Problem it solves ]

Transfer current between a fixed and a moving part without wearing the metal counterface or relying on a lubricant, which in an electrical contact would act as an insulator.

Operating conditions

Electrical sliding contact
Current conduction
Dynamic contact

When it is suitable

Current is transferred between parts in relative motion
The metal counterface must be protected from wear
A lubricant cannot be used because it is insulating
The contact is to be replaced as a planned wear part

When it may not be suitable

Sustained arcing occurs because the contact is undersized
Contact pressure is outside the brush-holder design range
The environment carries abrasives or vapours that prevent film formation

Process challenges

Contact wear
Electric arc
Overheating

Advantages

Good conductivity
Contact self-lubrication
Grades by current and speed

Limitations

Wear from arcing or electrical erosion
Conductivity and density must be calibrated to the process
Some grades are not suitable for high purity

[ Critical selection variables ]

These variables define the grade and the geometry. Actual values are confirmed against the grade datasheet.

Current densityDecisive
Sliding speedDecisive
Contact forceDecisive
Counterface material and finishDecisive
Humidity and ambient conditionsRelevant
Operating temperatureRelevant
Geometry and tolerancesRelevant

[ Required material properties ]

Properties that guide selection. Numerical values come from each grade's datasheet.

Critical properties

Electrical resistivity
Friction coefficient
Self-lubrication
Wear resistance

Secondary properties

Lubricating film formation
Hardness
Compressive strength

[ Related ]

[ Frequently asked questions ]

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Technical content reviewed by ESGRAF — Last reviewed: September 8, 2026

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