Hi All,

Have your ever seen shaft broken with shape like pictures attached? What could be the cause to make this kind of broken shape?

Thanks, Kevin Ku.

Shaft_broken.pdf (451 KB, 63 downloads) Broken shaft pictures

Excessive torque (static and/or dynamic) will cause fracture in a cone shape. A stress concentration at the shaft keyway was the probable starting point. Torque measurements are highly recommended, since this looks like a large and expensive machine.

Walt

I agree. Looks like this occurred over some time, as there is some hardening near the top of the last photo. Probable crack propagation over time. Would need more detailed photomicrographs to be sure.
Might also want to check on installation procedures, in case damage occurred in the keyway area during installation.