... Electroplated hard-chrome High-frequency quenching Spray coating Bimetallic-alloy Vacuum quenching Type of screw:for good plasticizing effect, we have different ... demand.Gradual type, mutant type, wave type, barrier type, double screen type, shunt type, separation type, exhaust type, pin type, mixed type, double-head type, three-head type, multi head type etc.It ...