Matching Relationship Between Commutator and Brushes

The Matching Relationship Between Commutators and Brushes

The matching relationship between commutators and brushes has a decisive impact on motor performance. The selection of brush material requires consideration of multiple factors, including current density, sliding speed, environmental conditions, and commutator material. Carbon-graphite brushes possess excellent self-lubricating properties and electrical conductivity, making them suitable for most general-purpose motors. Metal-graphite brushes, on the other hand, offer higher current-carrying capacity and are commonly used in high-current applications.

Brush pressure is another critical parameter. Insufficient pressure increases contact resistance, leading to overheating and sparking; excessive pressure accelerates mechanical wear on both the commutator and brushes. Ideally, brush pressure should be the minimum value necessary to ensure good electrical contact. Different motor types and applications have varying pressure requirements, with optimal values typically determined by motor manufacturers through rigorous testing.

The break-in process is critical for long-term performance. Newly replaced brushes require gradual adaptation to the commutator surface to form an optimal contact interface. This typically involves operating under light load for several hours, allowing the brushes to naturally wear into a shape matching the commutator's curvature. Skipping the break-in phase and running at full load immediately can easily cause brush fragmentation or abnormal commutator wear.