Hello Emanuel and welcome to the forum.
I am going to make two assumptions which you can clarify.
1. You are not using the manufacturing extension
2. You want to show the material removal as an animation
If you only wanted to make the cut, obviously you can do this in many ways, even at the assembly level by making an assembly cut.
To make this an animation, it is more problematic. The difference is that you will be changing the gear which requires regeneration between frames.
Let me know if I'm on the right track and we can look at options.
