Mechanical properties of oxide film on ELID grinding wheel surface

Oxide film on grinding wheel surface has significant effect both in guaranteeing non-linear electrolysis of ELID (electrolytic in-process dressing) grinding and in improving grinding surface quality. Nanoindentation technique was utilized to study the hardness, elastic modulus and stiffness of the oxide film. Study results indicate that the hardness of the oxide film is about 210 MPa, that is 1/4-1/3 of the matrix hardness, which enables the oxide film to effectively separate the matrix from the workpiece and prevents the matrix from scratching the grinding surface. The elastic modulus of the oxide film is about 30-50 GPa, which is 1/6-1/3 of the matrix elastic modulus, so that elastic deformation occurs more easily, which contributes to the concertedness and equal height of grinding grains. The stiffness of the oxide film is around 15μN/nm and depends on the grinding parameters due to the dynamic update of the oxide film. In precision grinding, the elastic deformation of oxide film results in reduction of the exposure and grinding depth of the grinding grains, thus enhancing the grinding surface quality accordingly.