For over 100 years carbon brushes have been an important component in electric motors. Their job is to create the electrical contact with the collector or the slip rings of the rotating part of the machine. However, many of the materials that carbon brushes are made from change their volume and swell under certain conditions. In particular, carbon brush materials that contain metal are affected by this phenomenon. As a result, extensive damage can occur to the components. Schunk has developed materials for slip ring and direct current motors which eliminate this problem.
With their use in direct current and alternating current motors, carbon brushes in electric motors made a key contribution to advancing the industrial revolution. Versions only a few grams in weight can be found in kitchen appliances, electrical window regulators, and garden equipment, while carbon brushes weighing several hundred grams are employed in wind turbines, locomotives, and power station generators. However, they all have one thing in common: due to high temperatures and humidity, they are exposed to extreme stresses. Conventional components made from metal-containing or resin-bonded materials change their structure under these conditions, i.e., they swell. As a result, the brushes do not hang freely in the holder and are then destroyed by an electric arc. The commutators or slip rings and the brush holders are also badly affected when this happens. Repairing and replacing the components is costly and plant downtimes and high costs arise as a result.
Materials for non-swelling carbon brushes
Schunk Carbon Technology is the world leader in the development, production, and application of carbon-based solutions. Our experts combine innovative strength and technological know-how to achieve an unrivaled performance range. As the operation of plants is intensified, the demands placed on carbon brushes also steadily increase. Particularly for wind turbines, in the wire industry, and in the cement industry, it’s necessary to use advanced materials that can cope with the changes in the performance range of the motors and generators. Schunk Carbon Technology has succeeded, due to careful selection of raw materials and production processes, in optimizing materials so that they retain stable form even in extreme conditions, and thus do not swell.
Schunk’s materials combine high electrical and thermal conductivity with extraordinary resistance to wear and tear. Solutions are custom-developed for the respective application according to a customer-specific design. This applies for a wide range of scenarios and customer requirements, for example in environments with a high dust content and high humidity, as well as in power surges, in idle phases, during light-load operation, or in abrasive media.
Customer benefits through innovation
Manufacturers that rely on non-swelling carbon brushes from Schunk benefit from the high operational reliability and dependability of the solution. The high level of resistance to alternating loads and the absence of swelling offer considerable added value due to the greater reliability of power transmission. Unplanned plant downtimes can thus be avoided and maintenance cycles optimized. Today, manufacturers of drives of all kinds all over the world trust in Schunk’s materials, which ensure perfect power transmission even under the harshest operational conditions. We also count the leading producers in the copper wire industry among our customers.