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The Benefits of Ceramic Bearings?


#1

A few of you already know that one of our main goals is to produce a board that is dependable, long lasting with a similar product warranty to what is available in the automotive industry. Finding weaknesses, points of failure and overcoming them has been key to the effort.

Our focus this week is wheel and motor bearings, although a decision was already made earlier this year to install ceramic wheel bearings in every board that leaves our facility and now we are contemplating the merits of going full ceramic throughout our drive train and motors. It is no secret that ceramic skate bearings last much longer than steel bearings, they can last 5 to 20 times longer in most cases. So our main focus now is what benefits will they have in brushless motors?

Will the ceramic bearings also provide a thermal break preventing the heat of the stator from transferring to the outer housing? If this is the case will it extend the life of the rare earth magnets and protect them against permanent losses?

Our first effort into finding the merits of installing ceramic bearings in our brushless motors was to get a baseline temperature measurement. The baseline measurement after a mile long hill climb showed both motors with steel bearings to be 41 degrees Celsius on the outer rotor housing. This shows that the motors are heating up equally and should provide a good comparison. Today we will perform the installation into one of the motors on a dual diagonal drive and see if there is any reduction in rotor temperature



#2

Does each motor have 2 bearings,…one on each end ?


#3

3 total on this model. What you see in the photo.


#4

These motors are built to your specifications ?


#5

Yes…however they would retail for a little over $100 if they came standard with ceramic bearings. Better to switch them out here in the shop with the quantities we are having made. One thing we did make sure of was the use of a larger 608 size bearing on the pulley side vs the small 688 bearings found in other motors.


#6

Are u doing shielded or sealed bearings. ? I thought the sealed’s seal would breakdown w the heat? Nsk rates their standard seals to 200f yet every motor I see has sheilded bearings. Maybe sealed is doable


#7

Did you ever mention something about the Sk3 motors that were superior to most,… just cant remember what it was ?


#8

The 608 ceramics are what I have on hand and the smaller bearings are what I could get quickly.


#9

Curious if use had success with sealed vs sheilded which seems to be the norm on a motor

Sealed would be nice on a board with the motor so low to the ground and it looks like u have seals. Some kind of seal. A bit more resistance but being inches from the dusty ground…id like sealed


#10

Very cool. Great to see ongoing innovation in something we typically take for granted (improving motors!).

I’m a huge fan of ceramic bearings - i run the tekton ceramics in almost all my boards. Spendy little buggers, but so smooth!!!

Continue to be impressed by your top-shelf offerings @Chaka! Definitely wouldn’t hesitate to get my next v6 VESC from you! Do you have any 63mm motors in the works?

It would be great to see thermal before/after images to see if it makes a big difference? I saw some the last week from another member - and i keep meaning to try similar w/ a less expensive FLIR One i got for Android…


#11

Sk3’s work well in FOC mode and they have a 3rd race supporting the rotor hence the name sk"3".

They still overheat the VESC on hills due to there higher “current” demand. Lots of factors, not every motor is best for every case.


#12

Ceramic obviously won’t transfer any where near as much heat as steel, but I would think the balls themselves aren’t the only thing transferring heat. The lube and shields would also transfer heat depending on what they are made of.


#13

The seals I am using on my skate bearings are stated to handle up to 150 °C. Should be fine but I want to abuse them first before committing. Another option is FKM seals that can handle as much as 200 °C. I would have to check the specs but I think that is right around the threshold for the enamel on the windings.

Honestly I think we see metal shields in brushless motors because of the lower cost or is it designed obsolescence? Engineerings dirty little secret.


#14

if you look deep into the heart of any electronic device, you’ll find conspiracy everywhere.

I’m also thinking of switching to Bones ceramics from the typical REDS that i always use if for no other reason than longevity.


#15

Bones are nice - i love their swiss 6. Also check out the Tekton ceramics - nice that they’re builtins. Super smooth and you can find them for quite a few $ less if you search.


#16

Do you plan to have the bearings be user serviceable in your motors? I know this makes a huge difference on sk8 bearings - a little cleaning and re-lube really extends the life.


#17

If the seals hold up.


#18

This sounds like a great application for ceramic bearings! I don’t see why there would be much of a thermal advantage since the inner and outer raceways are all going to be steel anyway. I’m curious to see if there is a difference!


#19

The races are separated by the bearings providing the thermal break.