Bimetallic barrel,screw barrel

There is an armouring layer on the top of screw thread, or on the surface of all over the screw working surface. It has a minimum contact wear ratio then it is running on the inside of cylinder. The base material is one kind of high-strength and weldable, nitridable metal. Between this armouring layer and the base material, there is perfect material bonding. These two kinds of material take different functions in hand, but form an uniform whole - The bimetallic screw