A system for process-technological machines such as mills and classifiers having an enclosed design with no rotary unions between the ambient air and system interior. This system is particularly useful for CIP and SIP operation modes or glove-box operations. The mills or classifiers include an encapsulation that seals the components of the magnetic bearing spindle drive against the working zone of the shaft in the magnetic bearing spindle housing. The magnetic bearing spindle drive is designed such that the shaft can be removed to facilitate simpler and easier component exchange as well as thorough cleaning.