Yes, for this machine you definitely ought to be looking at servos - especially at the cutting and jogging speeds you are talking about.
When you say an 8Nm motor -- wow, if that is constant torque then it is really big. Did they tell you the electrical power requirements for the motor? Are they DC servos or AC servos?
I did neglect one piece of data in my calculations, and that is the rotational acceleration of the drive screw you are using. That is a pretty large screw (I understand why you want it, because of the speed you are running). So, there will be force required to accelerate the screw itself. I had about 2x headroom in my calculation without the screw, so even with the mass and acceleration of the screw added, I still bet you need no more than a 3.5Nm motor.
I would shop for another quotation, and also challenge the servo company to explain to you how they did their calculations.
Out of curiosity, do you know how much the x-axis drive screw will weigh?
-Chris |