I am looking for a recommendation for a material for an application
The application involving two shafts. One shaft is about 35mm in
diameter x 330mm long. It has a 14mm bore in one end with a 6 mm x
27mm long slot through the shaft coincident with the 14mm bore. This
shaft is held is place by two ball bearings and is driven from the end
without the bore by a servo motor.
The other shaft is 12mm in diameter x 150mm long. It has a 6mm hole
though the shaft at one end. This shaft is inserted in the 14mm bore
of the other shaft. The 6mm hole is aligned with the 6mm slot in the
first shaft and a pin is pressed in the hole to transmit torque.
This assembly must be able to transmit 165Nm (110Nm with a 150% safety
factor) of torque at very slow speed. The total radial travel is less
that 180 degrees.
Both of these shafts are currently made from SAE 4340 and harden to Rc
48-52. I thinking maybe some other material might be better suited for
The problem is we're seeing 9-12 degrees wind up in this assembly at
110Nm and need to redesign.
We don't have much room to go bigger but do plan on making the smaller
shaft a little larger and the bore in the larger shaft larger
The shafts don't see much impact but the slot in the larger one does
need to be harden to transmit the load from the pin.
Any help specifying a material would be greatly appreciated.
- posted 15 years ago