Today's Wire EDM machines can cut even exotic metals to as fine as 4 millionths (.000004") of an inch, in increments of 40 millionths (.00004"). The newest machines cut at rates twice that of earlier generations.
All that power is great. The problem is maintaining a quality cut at production line speed. CNC control, premium wire, high flushing rates, and especially using high quality deionized water as the dielectric can make all the difference.