akoschier
Junior Member
Arnie,
DN stands for diameter in milimetres of inner race times RPM which is a figure of merit for bearings where at higher RPM's the centrifugal loading of the balls or rollers causes hertzian stresses in the outer race which significantly reduce the load carrying potential of the bearing.
In highly advanced high speed bearings designers now use silicon nitride (ceramic) rolling elements (balls or rollers) which because of the lower density oif ceramics reduce those stresses and permit higher loading than would be available otherwise.
The guy in England who makes model jet and turfofan engines and drone engines (Hewit) uses them. They run at 60- 180000 RPM
The repeated cyclic contact pressure of the ball or roller rolling over the outer race causes fatigue damage and breaking out of grains in the structure of the outer race which is the beginning of the end in a bearing life. The same is valid for the rolling element itself.
And as for the bearing cost- some whiles back (3 years) Alturdyne who bought the comercial rights to the Soilar T62 after they went belly up were selling advanced longer life bearings for 650$.
They no longer do that and want you to send the power head in for overhaul.
But there seem to be other ways.
avk
DN stands for diameter in milimetres of inner race times RPM which is a figure of merit for bearings where at higher RPM's the centrifugal loading of the balls or rollers causes hertzian stresses in the outer race which significantly reduce the load carrying potential of the bearing.
In highly advanced high speed bearings designers now use silicon nitride (ceramic) rolling elements (balls or rollers) which because of the lower density oif ceramics reduce those stresses and permit higher loading than would be available otherwise.
The guy in England who makes model jet and turfofan engines and drone engines (Hewit) uses them. They run at 60- 180000 RPM
The repeated cyclic contact pressure of the ball or roller rolling over the outer race causes fatigue damage and breaking out of grains in the structure of the outer race which is the beginning of the end in a bearing life. The same is valid for the rolling element itself.
And as for the bearing cost- some whiles back (3 years) Alturdyne who bought the comercial rights to the Soilar T62 after they went belly up were selling advanced longer life bearings for 650$.
They no longer do that and want you to send the power head in for overhaul.
But there seem to be other ways.
avk