Asked at work the designer-technologist, such as cut pancakes from billets of that diameter. Found out that for these purposes use a special cutting tools.

Cut billets with a diameter more than 40 mm for two times

Thin cutting cutter width of the plate 18-20 60% of the depth,
Wide parting-off cutter to the depth of

Cutting the cutter has the shape of a bow saw with one tooth, whereby a high rigidity of the large diameter cutting and vibration during cutting.
Feature processing such cut-off cutter is that the processing is done upside down to reverse the spindle rotation, in order that the shavings went into the trough or wound in a coil.Processed normally mills type 1Н65. We’re cutting cutters get the length for the pinion shaft from the material St 40KHN2MA.