Filling Air Gaps inside Stator Slots

[hias9]

Filling all the little air gaps inside the stator slots with thermally conductive material would improve heat conductivity from the windings to the slot papers / stator laminations.

Does anybody know a material that is suitable for this and gets into all those little gaps?

 

[jonescg]

Normally stators are dipped in varnish which more or less does that, but not enough to completely fill the gaps. So long as there's a path for that heat to make its way out to a heat exchange surface it can be done with various resins.

 

[Kodin]

They do exactly that for fully-immersed underwater outrunner motors. Pot the stator in epoxy making it one solid block or cylinder, put stainless or ideally ceramic bearings in, throw it back together. Some people also pack the space between bearings with grease, but that adds a lot of friction and won't save non-ceramic bearings underwater.