What causes excessive brushwear ac motor

[Guzrik]

Siemens washing machine.
Four years ago I turned the rotor down on my lathe, smooth and clean really proud of myself.
Original 45€ brushes so I expected a bit more then four years before getting f43 error (motor or brushes)
New machine is in place so I did a postmortum for academic reasons.
Think they were 19mm longer when installed.

Can anyone give a possible reason for this?

 

[brightspark]

possibly a segment winding down if its sparking . plenty of meat on that brush

 

[Erie Fred]

Did you undercut the mica after turning the comm ?
Did you check that the brushes moved freely in the holders ?

 

[Martin-Sy]

Did you undercut after turning?
See https://renown-electric.com/field-services/turn-undercut/


Or as @brightspark says may be a winding fault.

 

[Tom O]

Weak spring maybe?

 

[Blobber]

I've always found replacement brushes wear out quickly, genuine or not

 

[Brad93]

Vibration. Smaller comm dia = less surface area for brush to contact

 

[mike 109444]

Is this a 1400 or 1600 spin speed machine ?
If so they did not change a lot in the motors to gain the extra speed !
Also could be over loading machine (my wife does )

 

[brightspark]

I've always found replacement brushes wear out quickly, genuine or not

not all carbon compounds are the same some are harder than others. diffrent grades .if there 2 hard they can wear the commy out real quick

 

[Kram]

Often weak spring, only takes a little heat to soften them and then bad contact. May be worth fitting a spacer behind for a bit of preload.

Nothing wrong with the cheap brushes on amazon. I bought a set that were purposely oversized and filed them to fit.


£45 for some brushes! Likely insignificant compared to the time/pain/cost of getting to them though.

 

[brightspark]

£45 for some brushes! Likely insignificant compared to the time/pain/cost of getting to them though.

me bum would be chuffing if i spent more than a fiver on brushes

 

[Memmeddu]

Vibration. Smaller comm dia = less surface area for brush to contact

Which may cause less resistance too...
Consequently an higher current flowing through.
Brushes usually hit on 2+2 fins, a smaller contact area due to a smaller dia may cause a longer time spent on 3+3 fins causing the current to rise up.

 

[Memmeddu]

Is this a 1400 or 1600 spin speed machine ?
If so they did not change a lot in the motors to gain the extra speed !
Also could be over loading machine (my wife does )

It seems like a common 13000rpm DC motor.
And yes off course overloading it may or surely I might say play an important role

 

[Guzrik]

Did you undercut after turning?
See https://renown-electric.com/field-services/turn-undercut/


Or as @brightspark says may be a winding fault.

I can't remember, but I think i pushed/ dented the plastic in between a bit in, next time I'll mill it away a little deeper.
This indeed migth have been the root cause creating a bit of heat and vibration, weakening the springs.
Also the fit was not wide enough maybe also contributing to the final failure.
Thanks for all tips, the new machine is brushless but certainly nice to know anyway.
Think I'll take it apart for spares and sheetmaterial.
Can the pump maybe be used for a partswasher, pumping diesel and such?

 

[Guzrik]

It seems like a common 13000rpm DC motor.
And yes off course overloading it may or surely I might say play an important role

Dc? I (not a sparky) assumed ac, thanks.
Also I will communicate the overloading issue, maybe adding few years to the new machinelife.

 

[MattF]

Also I will communicate the overloading issue, maybe adding few years to the new machinelife.

It may add some time to the machine's lifespan, but that suggestion/discussion may likely shorten yours.

 

[Memmeddu]

Dc? I (not a sparky) assumed ac, thanks.
Also I will communicate the overloading issue, maybe adding few years to the new machinelife.

DC motor is another name for universal motor.
Practically every brushed motor which has stator windings is considered an universal motor as it doesn't care about being powered by AC or DC current

 

[winchman]

When you fitted the brushes did you shape them to the curve of the com?
Sticking spring is also a common issue.

 

[winchman]

me bum would be chuffing if i spent more than a fiver on brushes

When we first bought a house money was very tight, I managed to cut a set of Forklift truck motor brushes down to fit the washing machine as they were free.

 

[Keithmac]

4 years is not bad if it's used daily. I had 5 sets of brushes in our old washer (was a Candy or Creda?).

Bought a brushless Samsung EcoBubble this time round but I bet when the fancy electronics pack up it will be a lot dearer than a set of brushes..

My wife likes it though, she can set it off via the phone app.