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Quick question, are the brushes in a brushed DC motor supposed to be lubricated?

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  • \$\begingroup\$ No lubrication necessary. Consider how long your automobile heater/defroster/air conditioner blower motor lasts. \$\endgroup\$ Feb 27, 2013 at 13:55
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    \$\begingroup\$ Brushes are often made of graphite and graphite IS a lubricant. \$\endgroup\$
    – Curd
    Feb 27, 2013 at 15:14
  • \$\begingroup\$ @Optionparty Less than 4000 hours. Your average cars' life expectancy. \$\endgroup\$
    – winny
    Dec 5, 2017 at 23:00

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No, the lubrication would either insulate or short what it should not.

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This answer only applies to graphite brushes which are the most common type.

No, you don't need any kind of extra treatment for them. Professional power tools all use motors with graphite brushes and the only maintenance they need with respect to brushes is having the brushes replaced once they wear out.

Here's a curious detail about professional power tools that only supports the fact that no extra treatment is needed. A tool comes with "hard" brushes that live approximately 100 hours (total time of motor being on). The replacement brushes are "soft" brushes that live approximately 50 hours. The difference is that "hard" brushes are meant to fine-polish the motor collector but if you use them as replacement they will polish it too much and wear it down beyond repair. So you run the new tool with "hard" brushes, they polish the collector during a kind of break-in period, then they wear out and you switch to "soft" brushes for the rest of the tool life. Both "hard" and "soft" brushes slowly wear out and the peeled off graphite acts as a lubricant.

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  • \$\begingroup\$ That is interesting, do you have a reference, I would be interested in reading a little more about that. \$\endgroup\$ Feb 27, 2013 at 14:38
  • \$\begingroup\$ @GradyPlayer: I don't have a reference for "hard" v "soft" brushes. \$\endgroup\$
    – sharptooth
    Feb 28, 2013 at 8:27
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Don't add any, it will interfere with either the electrical, or mechanical properties. The brushes breakdown and produce their own lubricant (a fine graphite powder).

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    \$\begingroup\$ Here's a reference link: plantservices.com/articles/1997/001 I understand I'm 3 years late, but if it doesn't benefit you, then hopefully the link will benefit someone else. \$\endgroup\$
    – user99037
    Feb 2, 2016 at 5:46
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I had two micro dc motors, both were squeaking like in this video:

https://www.youtube.com/watch?v=L_0SKz8aHRk

and as the guy shows there, a tiny drop of oil helped them a lot also in my case.

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CRC 2-26 lubricant.

A plastic safe lubricant, penetrant, cleaner and corrosion inhibitor that helps prevent electrical malfunction caused by water penetration, humidity, condensation or corrosion. Non-flammable. It contain no silicones, CFCs or chlorinated solvents. Only a small amount needed to clean the commutator of a motor.

The CRC 2-26 breaks crud on commutator so it can be easily removed. Conductivity is restored by actually cleaning the metal, not by putting a conductive liquid over it.

It displaces moisture to prevent corrosion and helps restore water-damaged electrical equipment. Restores resistance values and helps stop current leakage.

Disclaimer: This post may sound like an advertisement but I have no relationship with CRC, I only report my experience and recommendation. This lubricant is inexpensive at popular local hardware stores in the U.S.

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