Ball mill is running in fixed speed. The barrel speed is decided by belt wheel or reduction device. Ball mill speed affects the ball and material movement and milling process.
(a) Ball and material rise when in low speed. When the angle of ball and materials is bigger or equal to the natural angle, they drop along the barrel. The distance is not enough, the milling function is low and the efficiency is low.
(b) When the barrel speed is in a certain speed that between low and high, the ball will drop along parabola after in a height position. The impact power is big and mill efficiency is high. The speed now is the best speed.
(c) When in a high speed, the centrifugal force makes the material and ball turning with barrel. No any impact and low efficiency.
The best speed is related with ball diameter, loading, shape, friction ratio. The normal turning speed is 0.7-0.8 times of critical speed. It can be adjusted in a range in 10%.