Universal power chuck takes bar or billet

A universal three-jaw power chuck with patented 'collet jaw' capability adequately bridges the gap between a universal chuck for billet/forging/casting and a bar machining collet chuck.

Slow change-over times when producing small batch quantities can often undo the gains achieved by sophisticated machine and cutting tools.

This situation can often be exacerbated when the change-over involves changing from a three-jaw chuck to collet machining of bar material.

At MACH 2006 on stand 5129, Schunk will be showing how this can be a thing of the past with the exceptional Rota NCD chuck with patented 'collet jaw' capability.

The Rota NCD chuck is a large through bore three-jaw power chuck based on the 'wedge bar' actuation system.

This provides efficient conversion of the axial forces of the drawtube to high radial forces of the chuck jaw actuation.

The Rota NCD 'wedge bar' system has teeth on the underside of the base jaws that mesh with the teeth of the 'wedge bars' positioned tangentially within the chuck body.

An advantage of this system is that the meshed teeth in the precision guided wedge bars restrict the outward movement of the base jaws as a result of centrifugal force when the chuck is rotating at speed.

This restriction of outward movement significantly reduces the typical loss of clamping force of the jaws on the component caused by centrifugal forces.

The result is the ability to clamp thin wall section components at lower pressures when stationary and maintain sufficient clamping force to retain their clamping at speed, thus eliminating distortion.

Relevant for small bar machining, it also enables a higher permissible maximum rpm to be specified.

In parallel to this, the hysteresis effect of the actuation of the jaws when stationary, to the loss of any clamping forces at speed (and the return of the original forces when the chuck is returned to stationary) have proven in tests to be negligible.

This has proven to be a significant complement to the design and construction of the Schunk Rota NCD chuck.

A full range of hard and soft top jaws are available with standard 1/16in x 90 deg serration reception, making it universally applicable for most applications.

To complement the hard and soft jaws, the chuck can accommodate Schunk's standard hard and soft 'collet jaws' on chuck diameters of 160mm to 315mm diameter via the Schunk patented 'collet jaw' system.

Bar diameters can be accommodated from 6mm with standard hard collet jaws with each jaw set covering a range of between 5mm and 9mm on diameter, depending on chuck size.

The collet jaw system covers a greater diameter range than conventional collets thus increasing their flexibility and cost effectiveness.

Standard soft collet jaws are also available to be bored out to suit individual requirements.

The combination of all of these features is a universal three-jaw power chuck that adequately bridges the gap between a universal chuck for billet/forging/casting applications and the bar machining capability of a collet chuck.

For the user of a CNC turning centre requiring truly universal workholding equipment the Rota NCD chuck from Schunk is the answer.

It not only eliminates the need for the initial capital purchase of both a three-jaw power chuck and a collet chuck but also eliminates the physically demanding and time costly exercise of changing between workholding principles.

* Schunk Intek UK at MACH 2006, NEC, Birmingham, UK, May 15-19, Hall 5, Stand 5129.

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