A holding sleeve has a sleeve body having multiple clamping slits, and an outlet portion. The clamping slits are defined longitudinally and radially in the outer surface, are arranged at even angular intervals and communicate with the knife hole. Each clamping slit has a first end and a lateral branch. The lateral branch extends laterally from the first end of the clamping slit and communicates with the clamping slit. The outlet portion is formed in the outer end of the sleeve body and communicates with the lateral branches of the clamping slits.

A holding sleeve has a sleeve body having multiple clamping slits, and an outlet portion. The clamping slits are defined longitudinally and radially in the outer surface, are arranged at even angular intervals and communicate with the rotary cutting tool hole. Each clamping slit has a first end and a lateral branch. The lateral branch extends laterally from the first end of the clamping slit and communicates with the clamping slit. The outlet portion is formed in the outer end of the sleeve body and communicates with the lateral branches of the clamping slits.

The invention provides a clamping system (1) for a rotary tool (70), for example a milling cutter or drill. The clamping system (1) includes a base element (10), a collet (30) and a clamping nut (50), said clamping nut (50) friction-locking the rotary tool (70) within the base element (10) with the collet (30). In order to avoid a relative rotation of the base element (10) and the collet (30), the clamping system (1) has a form locking anti-twist protection which blocks a rotation of the collet (30) relative to the base element (10).