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Sorta silly dc motor question

I've been fooling around with some tiny vibrating pager motors. These motors are .160" dia x .625" long with a .028 dia. x .120 long shaft. In MM that would be 4 x 16 with a .7 x 3 shaft. These tiny things are rated at 1.3 volts and 65mA. I mounted a relatively large (1.25" x.1") brass flywheel on the shaft and am now running it at 4.2 volts at

270mA. The motor gets hot with the extra work it's doing along with the higher volts and amps. As long as the bearings hold up will the motor life be about the same if it's mounted in a good heatsink to keep it cool? Will the higher voltage and amperage make the brushes wear out much faster? I'm looking for ballpark type answers. I know that without the complete motor specs it is hard to tell exactly how much the life will be shortened. Thanks, Eric R Snow
Reply to
Eric R Snow
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Thanks, Colin. This motor is so small i think it must have metal brushes. Looking closely at the motor using a loupe' it appears that there is a long plastic bearing at the weight end. This makes sense because that wieght would ruin a regular sleeve bearing pretty fast. The bearing is probably delrin or nylon. Both make good, self lubricating sleeve bearings. Eric

Reply to
Eric R Snow

I wouldnt expect to last anywhere near as long, but then not knowing how long it would last for normaly this is rather empty information. I expect they wernt even rated for continous use at their rated spec anyway.

It realy depends how over engineered they were to start with, if they have long carbon brushes they might last a reasonable time, if the have cheap metal strip brushes theyl wear out in no time at al probably.

the extra heat will probably cuase the bearings to become dry and wear out quickly, thats asuming the winding insulation survives the temperature. although the case of the motor might be cooled down by a heatsink the inside could stil get very high.

Ive often over driven motors but not by so much, the sort of motors destined for use in electric screwdrivers are great, I usualy find the bearings in them dont last long enough and have to replace them with miniture ball bearing type.

Colin =^.^=

Reply to
colin

anyway.

have

out

inside

destined

I remember now also ive run some very tiny motors in model servos at higher than normal voltage to get more oomph out of them, however they easily burn out (insulation failire), but this only hapened when they tried to settle past the end stop, adding some overload circuitry solved this problem.

Colin =^.^=

Reply to
colin

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