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Toolholding and Workholding/ Stationary Workholding

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Machining cast parts precisely from five sides

Magnetic clamping technology reduces set-up times, creates more flexibility, and assures hold for faces


At the heart of the magnetic chucks, are
pole-exchangeable AlNiCo magnets.
SCHUNK manufac-tures magnetic chucks
in square, parallel, and radial pole technology

Large cast parts are stable “backbones” in many machines. They are mostly invisi-bly integrated in the end product, but assure safe hold of the individual machine components and define the radius of movement of heavy aggregates. When cast parts are machined, precision plays an important role. Beyond that the following has to be taken into consideration: Set-up times have to be kept in the eye as well as high load factors. This is where innovative clamping solutions can give a com-petitive edge. This is why the machine manufacturer Kolbus counts on the mag-netic clamping technology from SCHUNK, the leading expert in toolholding, workholding and automation, for manufacturing their bookbinding machines. The advantages are excellent machining quality, fast set-up, high flexibility and an op-timum load factor of the gantry machining center.

The Kolbus GmbH & Co. KG in Rahden, Germany is a medium-sized flagship company in the field of paper-processing industry. With 1,300 employees, Kolbus offers the largest portofolio of bookbinding machines. More than 30 machine types for manufacturing books and bound products are distributed by the company worldwide, whereby the in-house production depth is extremely high. Their busi-ness activities comprise an own foundry to high-precise production up to assembly and customer service. More than 110,000 self-made parts are integrated in the present Kolbus machines or spare parts for predecessor models are in stock.

Optimum workpiece accessibility

For machining of various cast parts made of GGG 60, Kolbus uses a TFS 5-axis gantry machining center from Droop + Rein. For setting up workpieces, magnetic chucks from SCHUNK are used. With just one set-up, they allow an optimum ac-cessibility of large and heavy workpieces from five sides. The special plates in parallel pole technology from SCHUNK were designed particularly for the require-ments at Kolbus. An individually defined proportioning of the poles and indexing bores assure that the plates can be converted faster and safer. This way an espe-cially high flexibility is granted. Workpieces of different sizes and shapes can be manufactured on the same magnetic chuck. Because of the exchangeable pole extensions, the magnetic chuck excellently adapts to the contour of the workpiece, which assures a precise and safe hold. With these relatively low-priced wear parts optimum workpiece accessibility is assured. In addition the surface of the high-quality parallel pole plate is protected. Separate supports and substructures or rather time-consuming fine adjustment of manual clamping elements are no longer necessary. The pole extensions at Kolbus have a height of 142 mm and are used with spacers of up to 50 mm.

Deformation and vibration-free clamping

With the MAGNOS chuck one complete face of the cast part is clamped and evenly located. Deformations, workpiece warping, pinches due to punctual clamping or damage of the surface can be excluded – an essential advantage for manufactur-ing precise parts. With the magnetic clamping technology, workpieces can be clamped at a plane-parallelism of up to 0.02 mm. Moreover, MAGNOS minimizes vibrations during machining effectively and thus prevents the tools from damage. Especially in case of high-quality tools, tool costs are greatly reduced.


With MAGNOS one face of the workpiece is
clamped vibration-free. This allows an
optimum accessibility from 5 sides and a
plane parallelism of 0.02 mm.

Thanks to magnetic clamping technology, the
gantry machining center at Kolbus is fully loaded.

Via pole extensions and spacers, the magnetic
chuck perfectly adapts to the workpiece.

Magnetic chucks in particular, have
decisive advantages in handling large cast parts.

The special plates at Kolbus have an individually
de-fined proportioning. Thanks to indexing
bores, parallel pole plates can be quickly adjusted
to different work-pieces.

The M3 plates are special designs from SCHUNK.
They are equipped with an especially tight magnetic

Total holding force of about 50 tons

Due to special requirements, magnetic chucks with an especially high tightness are used at Kolbus. This allows Kolbus to manage the extreme distance between the workpiece and the magnetic chuck and to be able to cover the possible air gap. The total holding force of the special plates used at Kolbus can amount to 50 tons.

Synergy from permanent and electrical magnets

MAGNOS magnetic clamping technology from SCHUNK is based on the use of electro-permanent magnets. Power supply is necessary for activation and deacti-vation of the magnets, which makes handling extremely easy. The ferro-magnetic workpiece is positioned, power supply is activated, and in a shorttime the perma-nent electric magnet has a solid hold – even if the power supply has been switched off again.

Amortization even after a very short period of time

With MAGNOS, the workpiece is clamped in seconds, making the fine-adjustment of the clamping unit or conversion of the workpiece within a machining process, no longer applicable. Comparative measurements at users of the MAGNOS magnetic clamping technology have shown that set-up savings between 30 and 50 percent are possible and thus machine downtimes are considerably reduced. In this man-ner, capital investments in the new clamping technology amortize within a short period of time

Long-living design: The “inner life” is decisive

The magnetic chucks from SCHUNK are equipped with a stable steel base body made of C45 and a mono block design manufactured on state-of-the-art machining centers. Their stability, stiffness, and robustness avoid vibrations and thus assure excellent machining results and longevity of the magnetic chucks.

The special insulation is adjusted to the base body and assures an exactly defined pole-exchangeable magnetic flux of the parallel poles. The magnetic chucks in-clude electro-magnetic coils, which surround a pole-exchangeable AlNiCo magnet. The even winding and the additional insulation assure a controllable and stable magnetic flux. A multitude of AlNiCo magnets provide enormous strength which results in an excellent air gap coverage. On the electro-magnetic coil, stable MAGNOS parallel poles made of steel with galvanized surface are firmly fixed.

Special high-end sealing method pole clearances are filled with high-tensile two shift synthetic resin. This two shift resin, the nickel-plated plate body as well as the nickel-plated magnetic pole, protect the magnetic chuck against corrosion and makes it resistant against aggressive coolants. Customers benefit from the solid reliability and the long lifetime.

Low capital investment costs, flexible and independent

MAGNOS magnetic clamping technology can be used independently from ma-chines, does not require any planning, and does not presume any system technol-ogy and -connection. Interferences into the machine’s programming are not neces-sary. Therefore, the magnetic clamping technology can also be used as an addi-tional clamping solution in the modern production facility.

Comprehensive quality demands

As a worldwide market leader in the toolholding and workholding fields, SCHUNK attaches great importance on quality and customer service. The solid design of the magnetic chucks from SCHUNK assures longevity. The control unit is also compact and robust, what has proven itself in case of frequent switching processes. SCHUNK also offers a repair service for magnetic chucks of all manufacturers that is very cost-effective. This way SCHUNK wants to make a contribution that innova-tive technologies can establish.


Contact to SCHUNK GmbH & Co. KG in our Suppliers Profile
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