shortleg_69
Industrial
- Oct 20, 2019
- 1
Hello all.
I would like to thank everyone who can help me with a problem I'm facing at the job.
I received from a customer a small 12V DC- Motor as described in the subject that ran a couple of hours only but with a strange commutation signal and a low resistance at the contacts.
When I took off the rear cover with the brushes, I fond some metallic particles between the air gap among all the commutator's bars. This material seems came from the commutator and/or brushes.
The strange things are listed here:
1) Each brush has three fingers that touch the commutator (of course on different positions of its length)
2) The fingers have the wear dramatically different: the one on the top (the farther from the coil) is worn-out by 30%, the middle one is worn-out by 5% and the last one has 0% of worn out. Be aware that the same situation can be found on both brushes.
3) The particles accumulated, which generate shortcuts between the bars, are positioned only at the same level where the finger more worn-out rubs against the commutator.
So, I'm starting with the Root Cause Analysis, and I want definitely look for the causes and taking the corrective actions.
I though some possible areas where the investigations should be focused:
A) Commutator error (shape)
B) Different pressure of the fingers on the commutator
C) Possible mounting error
D) Layer (gold) of the commutator
E) Possible arching?
I hope someone can help me, every advice is really appreciated.
Regards
I would like to thank everyone who can help me with a problem I'm facing at the job.
I received from a customer a small 12V DC- Motor as described in the subject that ran a couple of hours only but with a strange commutation signal and a low resistance at the contacts.
When I took off the rear cover with the brushes, I fond some metallic particles between the air gap among all the commutator's bars. This material seems came from the commutator and/or brushes.
The strange things are listed here:
1) Each brush has three fingers that touch the commutator (of course on different positions of its length)
2) The fingers have the wear dramatically different: the one on the top (the farther from the coil) is worn-out by 30%, the middle one is worn-out by 5% and the last one has 0% of worn out. Be aware that the same situation can be found on both brushes.
3) The particles accumulated, which generate shortcuts between the bars, are positioned only at the same level where the finger more worn-out rubs against the commutator.
So, I'm starting with the Root Cause Analysis, and I want definitely look for the causes and taking the corrective actions.
I though some possible areas where the investigations should be focused:
A) Commutator error (shape)
B) Different pressure of the fingers on the commutator
C) Possible mounting error
D) Layer (gold) of the commutator
E) Possible arching?
I hope someone can help me, every advice is really appreciated.
Regards
