The highest geometric accuracy by milling process and lathing processing

[TimeStudy]

I want to know the highest geometric accuracy by milling process and lathing processing. Generally, the economic machining accuracy for milling finish is about IT7. And the surface roughness is about Ra1.6. However, what level geometric errors can be achieved correspondingly? What are the highest flatness and squareness errors for the finishing with lathing or milling operation?
Thank you!

[Andre' B]

Do some research on single point diamond machining.
http://www.google.com/search?hl=en&q...&aq=f&oq=&aqi=