Effects of the friction coefficient of a barrel on the grinding performance of a planetary ball mill

We investigated the effect of the friction coefficients of a barrel on the grinding performance of multi-layer ceramic capacitors (MLCCs) in a planetary ball mill. We formulated the motion equation of the MLCCs, including gravitational force, interactive force due to collisions and the drag force in a planetary ball mill, using the three-dimensional discrete element method. The contact model in a collision between two MLCCs is represented by the Voigt model. The linear velocity, impact and shear energy according to the friction coefficients of a barrel were calculated. The trajectory of a single MLCC and the linear velocity distributions of many MLCCs were analyzed. It was found that an increase of the friction coefficient of a barrel not only improves the shear energy, but also reduces the impact. Finally, grinding experiments using four barrels with different friction coefficients were conducted to verify the simulated result. The measured wear height accurately matches the height expected from the simulated shear energy.