Wet bead mills use small Beads/balls to mill product down, the size of these beads determines the efficient particle size that the bead mill can create. In a sterile environment the sterility of these beads can be just as complex as the milling itself, requiring a method to clean and sterilise. Commonly using a Fluidised Bed, or other washer, and Depyrogenation Oven to achieve this.
A wet bead mill, mills product by agitating the product with hard Beads effectively smashing the product down splitting it into smaller and smaller particles. A bead mill usually recirculates product around a larger tank to increase the amount of product milled in one Unit Procedure.