Author Topic: Cleaning a DC motor without disassembling  (Read 17441 times)

0 Members and 1 Guest are viewing this topic.

Offline WattsThat

  • Frequent Contributor
  • **
  • Posts: 788
  • Country: us
Re: Cleaning a DC motor without disassembling
« Reply #25 on: February 15, 2020, 12:36:53 am »
Rebuilding larger motors I've used silicon/dielectric grease since it doesn't evaporate as much as petroleum oils/greases ,won't effect plastic parts and is far more water resistant.I wonder if it would work as well on these smaller motors .

Silicone anywhere in a dc motor can be a very bad idea.

I something discovered years ago, the hard way, when brush life became a constant problem on larger industrial dc motors. We were using food grade silicone in open heated water baths as a release agent. This resulted in silicone being introduced into the force ventilated dc motors in the ppm range.

Over several months, this led to motor failures when then brushes wore down to the shunts in weeks rather than years. After much pain and suffering, it was discovered (but known to some dc motor experts) the problem was the silicone. When it makes its it way to the brush-commutator interface, it may oxidize with the heat and you’ll end up with bits of things that resemble silicon carbide. The oxides embed themselves in the soft carbon and threading of the commutator follows. Then the brush wear accelerates very quickly and results in total failure when not caught in time.

I don’t know how factual this is but one of the dc motor old timers I encountered that knew about the silicone problem also mentioned that back in the sixties, Western Electric had prohibited silicone as a lubricant in any process that supplied parts that ending up in telephone switching stations. The reasoning was that silicone migrates everywhere and when it makes its way into the contacts of relays, it leads to shortened contact life due the wear caused by the oxides created in an arcing environment.
 
The following users thanked this post: Ian.M

Offline amyk

  • Super Contributor
  • ***
  • Posts: 8526
Re: Cleaning a DC motor without disassembling
« Reply #26 on: February 15, 2020, 03:06:03 am »
I wouldn't hesitate to disassemble that type of motor if it really needed cleaning and oiling. Pry the small crimps from the case and the end cap should come right off.
 

Offline Jwillis

  • Super Contributor
  • ***
  • Posts: 1725
  • Country: ca
Re: Cleaning a DC motor without disassembling
« Reply #27 on: February 15, 2020, 09:41:52 am »
Silicone anywhere in a dc motor can be a very bad idea.

I something discovered years ago, the hard way, when brush life became a constant problem on larger industrial dc motors. We were using food grade silicone in open heated water baths as a release agent. This resulted in silicone being introduced into the force ventilated dc motors in the ppm range.

Over several months, this led to motor failures when then brushes wore down to the shunts in weeks rather than years. After much pain and suffering, it was discovered (but known to some dc motor experts) the problem was the silicone. When it makes its it way to the brush-commutator interface, it may oxidize with the heat and you’ll end up with bits of things that resemble silicon carbide. The oxides embed themselves in the soft carbon and threading of the commutator follows. Then the brush wear accelerates very quickly and results in total failure when not caught in time.

I don’t know how factual this is but one of the dc motor old timers I encountered that knew about the silicone problem also mentioned that back in the sixties, Western Electric had prohibited silicone as a lubricant in any process that supplied parts that ending up in telephone switching stations. The reasoning was that silicone migrates everywhere and when it makes its way into the contacts of relays, it leads to shortened contact life due the wear caused by the oxides created in an arcing environment.

That's good to know. Most motors I deal with are 1/2 horse and higher AC. Tiny motors I don't lubricate at all. The high temp silicon greases don't migrate and I haven't had any problems with them getting into the commutators if used sparingly.  Any grease or oil on graphite brushes will damage them .Most electric motors don't require a lot of lubrication anyway . Just a small amount on the bearings. 
 

Online Zero999

  • Super Contributor
  • ***
  • Posts: 20364
  • Country: gb
  • 0999
Re: Cleaning a DC motor without disassembling
« Reply #28 on: February 15, 2020, 01:02:53 pm »
Silicone anywhere in a dc motor can be a very bad idea.

I something discovered years ago, the hard way, when brush life became a constant problem on larger industrial dc motors. We were using food grade silicone in open heated water baths as a release agent. This resulted in silicone being introduced into the force ventilated dc motors in the ppm range.

Over several months, this led to motor failures when then brushes wore down to the shunts in weeks rather than years. After much pain and suffering, it was discovered (but known to some dc motor experts) the problem was the silicone. When it makes its it way to the brush-commutator interface, it may oxidize with the heat and you’ll end up with bits of things that resemble silicon carbide. The oxides embed themselves in the soft carbon and threading of the commutator follows. Then the brush wear accelerates very quickly and results in total failure when not caught in time.

I don’t know how factual this is but one of the dc motor old timers I encountered that knew about the silicone problem also mentioned that back in the sixties, Western Electric had prohibited silicone as a lubricant in any process that supplied parts that ending up in telephone switching stations. The reasoning was that silicone migrates everywhere and when it makes its way into the contacts of relays, it leads to shortened contact life due the wear caused by the oxides created in an arcing environment.

That's good to know. Most motors I deal with are 1/2 horse and higher AC. Tiny motors I don't lubricate at all. The high temp silicon greases don't migrate and I haven't had any problems with them getting into the commutators if used sparingly.  Any grease or oil on graphite brushes will damage them .Most electric motors don't require a lot of lubrication anyway . Just a small amount on the bearings.
Well your furnace fan motor will no doubt be AC and will have no commutator, so there will be no problems with arcing, as would be the case with a DC or universal motor.
 

Offline andy3055

  • Super Contributor
  • ***
  • Posts: 1159
  • Country: us
Re: Cleaning a DC motor without disassembling
« Reply #29 on: February 15, 2020, 09:47:11 pm »
For such small motor bearings, I use Tri-Flow:

https://www.triflowlubricants.com/product/tri-flow-superior-lubricant-drip-bottle/

For bearings (re-packing) and larger/medium size motor bearings, I use Teflon Grease similar to this:

https://www.fastenal.com/products/details/4123728

Teflon grease is good for bearings that are installed in high temperature locations.

 

Online mikerj

  • Super Contributor
  • ***
  • Posts: 3384
  • Country: gb
Re: Cleaning a DC motor without disassembling
« Reply #30 on: February 15, 2020, 10:06:12 pm »
Back in my youth when I was into RC cars the way to run-in new 540 motors and clean used ones was to run them under water (from a battery pack).  The amount of crud that gets flushed out of the vents is amazing, though obviously the motor must thoroughly dried and bearings re-lubricated afterwards.
 
The following users thanked this post: aeberbach

Offline Jwillis

  • Super Contributor
  • ***
  • Posts: 1725
  • Country: ca
Re: Cleaning a DC motor without disassembling
« Reply #31 on: February 15, 2020, 11:45:35 pm »
Silicone  greases can support temperatures from -150° F to 600° F ., contain no harmful or flammable petrochemicals and some  also be have  Teflon  (Polytetrafluoroethylene (PTFE)) added. The problem with Teflon lubricants are the carriers and Teflon is not the primary lubricant . Tri-flow primary lubricant is Naphthenic Petroleum Oil and the  Teflon accounts for around 1% by volume.
Also consider that most heat sink compounds are Silicone grease based.
Regardless of what you use keep all  lubricants out of the commutator.
 

Offline mcovington

  • Regular Contributor
  • *
  • Posts: 191
  • Country: us
Re: Cleaning a DC motor without disassembling
« Reply #32 on: February 16, 2020, 03:39:22 am »
Spindle oil was mentioned.  What do people think of Marvel Mystery Oil as a very light, penetrating lubricant?
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf