Refers to a type of tool clamping systems for machine tools, such as CNC-machining centres. In the hydraulic chuck the tool is inserted into the tool holder without backlash. Here, in contrast to the shrink fit toolholder, the tool can be released and clamped by the operator at any time.

Mode of Operation

Within the tool holder there are voids, which are filled with fat. The side walls around the tool shank are very thin. Using an adjustable screw, the pressure can be increased in the entire hydraulic system, whereby the thin side walls are pressed to the tool shaft. Because of the pressure distribution at each point being always uniform in a hydraulic system, the tool is clamped exactly at the center and completely free of play.

Advantages over other tool holders

• Compared with systems with collet: tight and perfectly centered (and thus absolutely precise) clamping of the tool.
• Compared to shrink fit tool holders: easy tightening and loosening of the tool without expensive extra equipment.

Disadvantages compared to other tool holders

• Each chuck is used only for one tool diameter.
• Relatively complex system, therefore, higher costs for the chucks and more prone to errors and defects.

Alternative terms

• Hydro Power
• Hydraulic clamping system
• Hydraulic chucks

Related terms

• ETP Hydro-Grip