Developing blade and its manufacturing method

A method for manufacturing a developing blade comprising a blade member along one side edge of a support member, characterized by:

• using as the support member a material having a coefficient of elasticity in the range of 0.5×104 to 4.0×104 kg/mm2 and a moment of inertia of area (Iz) in the range of 6.5E-04 to 1.2E-02, using as the blade member a rubber material having a 25% modulus of no greater than 0.85 MPa and having a moment of inertia of area (Iz) in the range of 8E-02 to 1.2E+01, and using as a mold assembly a top mold comprising a mold surface with a cavity formed for the formation of the blade member and a gate in communication with said cavity, and a bottom mold having a flat mold surface, wherein while said cavity is closed up with said support member and the neighborhood of said side edge of said support member is held between the edge of said cavity in the top mold and the bottom mold, the top and bottom molds are brought in alignment and clamped together, so that a molding material is poured from said gate into said cavity.