Schunk Prismo flexible precision grinding toolholder with manual actuation

The Schunk Prismo tool grinding toolholder clamps all shank diameters from 5 to 20 mm. Its repeat accuracy error – put at less than 0.005 mm at an overhang length of 2.5xD and a tool diameter of 20 mm – is owed to its variable clamping diameter, three-fold prism guidance and chuck jaws that intermesh into each other. Each of the five chuck jaws is guided by a double prism. Another prism is machined on to the clamping surface which is in contact with the tool shank. At the same time, the toolholder can be precisely adjusted to the individual tool diameter. For manual actuation, the axial spindle of the grinding toolholder is moved with a radial actuation screw and operates via an internal mechanism that consists of a worm and worm gear. The defined tightening torque amounts to 8 Nm. Its set-up and the robust design give the Prismo toolholder extremely high rigidity, says Schunk. The toolholder is rinsed with clean oil during the grinding operation to avoid contamination and to maintain consistently high precision. The X-axis of the grinding toolholder remains immobile independent of the tool diameter being machined. All the chuck jaws remain at an identical axial position. Costly additional programming and the risk of collision due to unconsidered off-sets of the X-axis are no longer a concern, maintains Schunk. The prism toolholder is tested for speeds of up to 2,500 rpm.