Fabrication of high heat flux (10-20 MW/m2) components for the International Thermonuclear Experimental Reactor ...required machining of the selected CuNiBe alloy to incorporate complex coolant channels...1-1.5 mm wide and 4-6 mm tall or deep at spindle speeds of 12,000 to 15,000 rpm with feed rates of 160 ipm.
Details (I Condensed the Statement Above) can be found
here.