The profile of cycloid-arc screw compressor rotors is not a smooth profile, it has a tip on it. When design the hob cutter used far machining this kind of rotors, the profile of hob edge will appear separation. In this paper, the author made a researches on the design theory of hob cutter for hobbing the cycloid-are rotor with tip profile, and got the best way for design this kind of hob cutter with a separate edge. It is good practice to design the hob cutter and hob the cycloid-are rotor according to practical design, manufacture and test.
