Hi Juan - Your machine is very small and will not require high G's or high velocities. High G's require more powerful motors and thats $$$ look at N17 motors as they may do the job. N23 can be quite powerful and they do run quite big machines. In the commercial world you will design the machine then do a value analysis. You will determine the total build budget then apportion the cost of bits vs their functional value. For your machine you maybe over capitalizing on the motors within the project so consider N17's... so do the math to make a performance vs $$$ decision vs just picking some motors.... 0.2g is quite respectable and will change the torque requirement dramatically...Peter
4000mm/min at 400rpm is a 10mm pitch screw. You probably want a 1605mm pitch or 1204mm pitch for a good force so you won't get to 4000mm/min. Look up the torque curve of the motor.....
say you use a 1605 screw at 500rpm thats only 2500mm/min maybe 750rpm gets 3750mm/min so maybe there...