Appropriate Acceleration Rate for Machine Tools?

Chaps,

As part of a CNC conversion of a Hardinge HC lathe, I'm using the Parker Motion Sizer software to select the correct sized servo motors and drives. (I will most likely be using Parker BE or Neometric series motors and Gemini GV series drives, as I have access to a range of 2nd hand ones.)

So, I've populated the fields in the Parker software with what I consider to be the appropriate feed and rapid speeds, mass/inertia of moving elements, friction, thrust forces, etc. Some of these figures were copied from performance specs for smaller gang tool CNC lathes, and include: 350kg Z thrust; feeds of 125mm/s; and rapids of 300 mm/s.

The problem I have is selecting an appropriate acceleration rate. If they were steppers, I would just build the machine, and increase the acceleration rates until I lost steps, and back it off a bit. This time round, I need to define the value to select the motors with a suitable peak torque rating. Considering that the Z axis will move a 110kg carriage/crosslide assembly, and the Y axis a 50kg crosslide and tools, what would be an acceptable acceleration rate in mm/s² ? For initial sizing, I've used figures which range from 2000 to 6000mm/s², which are achievable, but frankly, I'm have no idea what commercial machine tools are capable of.

Hence, I would be thankful of any advice you could provide.

Cheers, Steve