Milling System

How pharmaceutical manufacturer could fulfill Atex in grinding processes

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New Performance Characteristics

The first and most important step was done, notably defining the hammer mill as the size reduction process. Logically, conceiving the new process followed. A pivoting post hoist column, a pneumatic conveying system, and the Hammerwitt with the containers to be filled, are all located in the Atex zone; whereas the switch cabinet and control panel are outside the Atex hazard zones.

The characteristics of the individual system components contributed to a significant performance improvement in the entire system. The Hammerwitt made an important contribution by doubling throughput and its ability to mill the product with a rotor execution of 24 blades (the competitor’s rotor was fitted with 16 blades) in order to mill a finer product (75 µm).


The Profi-Valve, another Frewitt component, replaced the feed screw. It reduces the risk of blockage to zero due to its completely new rotary valve design, and provides constant product feed due to it’s volumetric dosing capacity explicitly designed for the capacity of the Hammerwitt milling chamber.

The final benefits are provided by the Frewitt Profi-Clean filter, which regulates the pressure in the milling chamber, and provides constant filtered exhaust through the particle separator. It monitors and regulates the exhaust air to ensure that the product does not heat up, which contributes to constant, high throughput. The Profi-Clean system is outfitted with an H13 filter which prevents the escape of the finest dust or powder. The filter is continuously cleaned via an efficient back-blow system.

The user was at the center of the system’s concept. A lifting column could accommodate containers up to a height of 2700 mm, resulting in containers with capacities of 300, 600, 1200 and 2000 liters can be quickly and safely filled in compliance with GMP standards.

Another advantage: The new milling design provides unparalleled flexibility, being quickly changeable from the Hammerwitt hammer mill to Frewitt's Turbowitt cylindrical mill. It is now child’s play to mill Product A, then switch to deagglomerating Product B within minutes, thanks to Frewitt's Fredrive system and its interchangeability.