Advice on suitable DC drive

Hello.

I have the possibility to acquire a non working machine to retrofit (milling machine).
The drives are not working (not sure if all) but even if they are working they are almost 30 years old, so I prefer to replace them.
The motors plates are on attachment. I would acquire the machine if I was able to buy new drives (3 units) up to 1500€, this is 500€, each drive.

The machine mechanics are very good, ballscrews 40mm, glass scales on XY axes (on Z I was not able to see it, but probably it also have), so my immediate concern are the motors. I could also acquire motors+drives but for this power I think that the price would be over killing.

Peak torque is 54Nm at 93 Amperes !



Any recommendations?
Thank you.

I am not exactly an expert in what kind of motor drives are available, but it seems that Mesa's 7i29 could work as a cost effective solution and you are a reseller of that brand.
Single channel current would be limited to 'only' 22,5A, but that is still good for operation above the continuous torque rating of the motors. Maybe it is possible to parallel the two channels of a 7i29 to obtain 45A current capacity.

The tacho would require something extra, not sure what. I think I would consider replacing the tachos with an encoder or resolver; that would give you accurate velocity information faster than a tacho does.

Thank you, honestly I didn't knew about the 7i29 (I do not stock it). I must consider it.

The 7i29 with a 5i20 or 5i22 will work well for your application. The 7i29 has an encoder input for every channel.

I am using the second approach: encoder on the servo used for primary positioning, low bandwidth Igain-only secondary loop to process the difference between actual position and assumed position. It took a while to optimize for real loads, but it works very well now.

If the scale is used as the only position feedback one has to be very, very sure that there is no lost motion in the system. Not in backlash, not in ballscrew torsion, not in belt springiness, not in scale encoder slide suspension. I tried it just for fun to see if it is really that bad, but the slightest lost motion either makes the system go wild or requires sluggish settings. But that was with the motors in torque mode; in velocity mode (when the tacho is used for feedback) it should be much better.