Need Help!- CNC pocket problem

[r_romeo]

Hi guys , I am a new on business , basically I have problems with a pocket that is 5.1mm wide . I am using a 5mm diameter end mill
I don’t know if I should use a smaller mill or the work is not well tight but does not seems to.
Here is the picture of the finish work , the cad and a copy of the G code if someone can give me a hand can be helpful, thanks

[Khalid]

seems ur stepping motor loosing steps, this may be due to
1- Interferense noise in cables near stepper motor
2- check your controller card for loose wiring
3-slow the IPM of z-axis and depth of cut

[r_romeo]

Thanks Khalid, Finally I found the problem, was that some screws that fixed the Z-axis were not there , making a small shaking.