3 Reasons Motor Brushes Wear Out Fast

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A common question from those handling DC motor maintenance is, “why are my motor brushes wearing so quickly?”. Rapid brush wear is a problem that can be caused from a multitude of factors. There isn’t one easy answer to this question, as each situation can be different. A natural answer to this question that many will quickly jump to is the carbon brush grade. However, we’ve seen that, more often than not, the brush grade is not the culprit. Here are three of the most common reasons for rapid carbon brush wear:

1. Low Spring Pressure

Inadequate spring pressure can cause rapid electrical brush wear. Clock and finger style springs tend to lose force as the brush wears, and all springs will fatigue over the course of time. This will reduce the effective force at the brush face and increase the rate of brush wear.  Reference our Recommended Spring Pressure Chart for more.

2. Poor Commutator or Ring Condition

A rough, out of round, or otherwise poor contact surface can cause accelerated brush wear. A poor commutator condition can lead to both electrical and mechanical wear of the carbon brush. Industry recommendations are for the commutator surface to be round within .002” for proper brush contact. An out-of-round ring will also cause the springs to flex more often, leading to shortened spring life and risk of inadequate spring pressure.

3. Brush Holders are Unequally Spaced or Out-of-Neutral

Improperly mounted brush holders can cause a variety of issues including brush wear. Brush holders that are installed incorrectly have the potential to cause damage to the contact surface and wear out a carbon brush faster.

It’s important to note that each situation is unique and there could be many other reasons for accelerated carbon brush wear. For instance, motor operating conditions can play an integral role in carbon brush life. Helwig Carbon’s engineering team has the experience and know-how to get to the bottom of any problems in the brush circuit. If you have questions about motor brush wear, contact us today to get to the root cause.




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