If a sharp, shrill sound is heard inside the grinding mill cylinder during operation, and this continues for an extended period, the mill should be stopped. Check for broken or damaged liners and ensure the feed rate is sufficient. These are generally the two main causes. However, sometimes, during minor or intermediate maintenance, carelessly leaving a wrench or other iron object inside the cylinder can also cause abnormal sound.

If there is an intermittent, muffled impact sound inside the cylinder, it may indicate that a liner has detached. If the ball mill suddenly discharges small steel balls and ore chunks, it indicates damage to the internal grate plates.