Spannhülsen

Spannhülsen are cylindrical clamping components used in machine tools and fixtures to secure tools or workpieces. They typically operate by applying an axial tightening force that is converted into radial clamping force through a wedging, taper, or expanding mechanism. They are mounted in tool holders, chucks, grippers, or base fixtures and enable quick, repeatable clamping with high concentric accuracy.

Construction: a Spannhülse is usually made of hardened steel or a wear-resistant alloy. It has an inner bore designed to accommodate the tool shank or workpiece, and an outer seating surface that interfaces with the holder. Clamping is achieved by a tightening element such as a screw, drawbar, or hydraulic/pneumatic actuator; the tightening action drives a wedge or expansion to grip the inner component securely. Some versions use a split or segmented design to produce uniform clamping around the circumference.

Applications: Spannhülsen are used in a variety of contexts, including milling and drilling tool holders, grinding fixtures, and precision jigs. They enable rapid tool changes, improved runout control, and reliable repeatability, especially when dealing with interchangeable tools or delicate workpieces. They are often used in combination with standards such as metric tool shank diameters or ISO tool holders.

Advantages and considerations: benefits include strong, repeatable grip, reduced runout, and ease of tool change. Selection depends on the required clamping force, shank size, and fixture design; improper installation or contamination can degrade performance. Proper seating, alignment, and maintenance are essential.

See also: Collets, chucks, tool holders, clamping fixtures.