Dave, You may have noticed many questions pertaining to bearings / spindles will eventually involve the resident bearing guy NC Cams. Pay attention, he knows of what he speaks though sometimes a bit "disciplining".
Is the process you refer to similar to simple friction welding where parts are forced against each other while they are counter rotating? If so, that axial force will have to be quantified and compensated for.
Ref. heat: how much will reach the bearings and soak into the spindle?
What about torque required?
I'm sure NC Cams will inquire of more required info, but hopefully this will start the discussion and helpful suggestions.