I'm helping out with a little bit of design work at a small aerospace company, they've just lost there full time Mechanical engineer and are having a number of issues with some parts turning up. One of these parts are brass flywheels for an inertia wheel model.
The motors that are being used are faulhaber brushless motors with a 1.5mm shaft (+0/-0.01mm) Which I believe would make this an h7 fit. Our issue is the previous engineer has specified a rather loose fit on the reaction wheels (though unfortunately I can't measure it I'd estimate they're ~1.6mm), these have been balanced but when glued to the shaft do not sit concentrically and have induced a vibration into the system. As they are inertia wheels, (unlike reaction wheels) they spin all the time, so this is quite an issue. To compound the issue the wheels have to be mounted after the motor is in the assembly as no access has been left for motor fasteners, this means jigging is very difficult.
The technicians have been pulling the wheels off and resetting them which has damaged the motor bearings. Awkwardly, even if there was a way to press on the flywheel, there is no way to support the axle as it does not protrude from the back end of the motor (the whole unit is encased in plastic, I believe in the rear is an encoder)
My current thoughts are that redesigning the wheels with a shrink fit and access holes/spokes for the motor mounting would be the best solution for this, but getting the required tolerance on such a small hole may be unachievable for us, the fairly loose tolerance on the shaft may make this especially difficult. Specifying an H7/H8 on the hole creating a fairly close clearance fit and using a loctite 648 may be the most sensible option.
Any thoughts or suggestions would be greatly appreciated.
The motors that are being used are faulhaber brushless motors with a 1.5mm shaft (+0/-0.01mm) Which I believe would make this an h7 fit. Our issue is the previous engineer has specified a rather loose fit on the reaction wheels (though unfortunately I can't measure it I'd estimate they're ~1.6mm), these have been balanced but when glued to the shaft do not sit concentrically and have induced a vibration into the system. As they are inertia wheels, (unlike reaction wheels) they spin all the time, so this is quite an issue. To compound the issue the wheels have to be mounted after the motor is in the assembly as no access has been left for motor fasteners, this means jigging is very difficult.
The technicians have been pulling the wheels off and resetting them which has damaged the motor bearings. Awkwardly, even if there was a way to press on the flywheel, there is no way to support the axle as it does not protrude from the back end of the motor (the whole unit is encased in plastic, I believe in the rear is an encoder)
My current thoughts are that redesigning the wheels with a shrink fit and access holes/spokes for the motor mounting would be the best solution for this, but getting the required tolerance on such a small hole may be unachievable for us, the fairly loose tolerance on the shaft may make this especially difficult. Specifying an H7/H8 on the hole creating a fairly close clearance fit and using a loctite 648 may be the most sensible option.
Any thoughts or suggestions would be greatly appreciated.
