How good stepper motors with feedback?

Hi all.

Currently I use steppers with open loop control and they are loos steps much and can work only very slowly.

Can I buy driver for closed loop stepper and connect it with encoders. Steppers are for example ES-D Series of leadshine? Can this driver or other similar fix my problem with losing steps?

I concur with Andy. You should look at your max acceleration and max velocity. If those are too high you will get slip. You will not get more performance from the motors if you add closed loop control. You can however increase the stepper supply voltage to as much as 80v. Make sure that you drive can handle that kind of voltage.
This will give good speed performance.

The mechanical part is definitely well designed, all parts turns well.

The problem possibly could be in because I have may be little high impulse per sec.
The system starts to slip always in one direction - from the object of processing. I will try today to adjust new settings with higher speads and lower steps per imp.

Really problem was in signal side and Chines drivers.

Don't believe what written on them. Dividing steps was messed completely. Where written 1/8 there is 1/256 and where 1/128 - there 1/5.

After this I tuned system well.

Thanks all for saving me from extra expenses.