Ball mills work by using balls to grind materials. Materials such as iron ore, pain, and ceramics are added to the ball mill. Next, the ball mill is activated so that it rotates — either on its vertical or horizontal axis. As the ball bill rotates, the balls bounce around while striking the enclosed material. The force of these strikes helps to grind the material into a finer, less-coarse medium.

For a ball mill to work, critical speed must be achieved. Critical speed refers to the speed at which the enclosed balls begin to rotate along the inner walls of the ball mill. If a ball mill fails to reach critical speed, the balls will remain stationary at the bottom where they have little or no impact on the material.