Japanese Nightmare 2

[Craig61]

I have a problem with an oil cooled Hitachi-Seiki AC spindle motor. I hope someone can help. "O" ring grooves machined directly into the lamination stack and the stack itself, were designed to seal coolant oil from the rotor/bearing area. After a rewind, we can't get the stator to hold 2 bars of air pressure. Even after epoxy VPI, trickle impregnation, microsealing the stack OD, and even using Glyptol under a vacuum, we still get a leak out of the stator slots at the head of the winding. Any information or someone's past experience to remedy this situation will be greatly appreciated. Thank you.

 

[jbartos]

Suggestion: If you happen to have another motor that is identical, it may be worthwhile to attempt reverse engineering.

 

[sreid]

I think that most impregnation processes attempt to stick most of the windings together to stop mechanical movement of the wires but probably don't necessarly seal every void. Once the voids are present it is likely difficult to get any additional impregnation into them. The original motor impregnation process probably used an impregnation process that was better at filling all voids. The current varnish buzz word is Thixotropic.