(1) trimming drawings how to proceed?

Drawing of the cutting edges, if it is a cylindrical workpiece can lathes on the cutting edge, you can also do a trimming die for the cutting edge. If a non-circular workpiece, it can only be used on the cutting edge of the trimming die.

(2) expand the drawings how to calculate?

Drawing blank area is not constant, it is subject to the mechanical properties of materials, the geometry of the mould, lubricated, the geometry of the workpiece, drawing coefficient of various factors, such as the effects of change. Therefore drawing no direct calculation formula.