Design of form milling cutters with multiple inserts for screw rotors

Form milling cutters with multiple inserted cutter blades are widely used in roughing screw rotors. This paper proposes a mathematical method for finding the distribution of cutter body inserts that will result in an equal wear rate for their cutting edges. First, commercially available standard inserts are selected and positioned in the form milling cutter axial section to satisfy profile geometry tolerance. Next, the insert tool life in every position is estimated based on its cutting material volume and corresponding wear rates. To even the insert wear rate and increase tool life, multiple inserts can be used at the same insertion position. Once the numbers of insert positions and inserts at each position have been explicitly defined, the inserts can be distributed on the cutter body periphery in a spiral form. Not only is the operational cost of such form milling cutters far less than that of cutters using special order blades, but the fact that all inserts are chosen from standard blades and can be replaced when the cutting edge becomes dull makes geometric precision easier to maintain.