Optimally adapted: frameless motor for thread forming tools

To design a direct drive for thread forming tools in punching machines – this was the challenge at the center of a joint development project by EHRT Maschinenbau GmbH and WITTENSTEIN cyber motor. The key requirements were to increase the level of performance despite smaller mounting dimensions and achieve optimal integration into the existing machine architecture. The result – in less than six months the two partners came up with a dynamic and highly compact drive unit.

Impressive example of cooperative forward integration
The roles within this partnership were clearly charted out: EHRT developed the drawing parts while WITTENSTEIN designed a frameless motor to the customer’s specification with components from the cyber® kit motor basic toolkit. The two partners’ respective components are now being assembled into a drive unit and function-tested by qualified personnel in defined processes at WITTENSTEIN cyber motor. EHRT profits tremendously from WITTENSTEIN cyber motor’s know-how and process reliability. The engineering company is not forced to develop expertise in motor assembly but is free to concentrate on its core business. This project is an impressive example of how cooperative forward integration can work in practice.

Punching and bending machines to customer specifications

EHRT Maschinenbau

A world leader

EHRT Maschinenbau GmbH of Rheinbreitbach has been developing and producing punching and bending machines for more than 50 years now. During the last half a century, the company has grown to become a world leader for precision machining of flat materials thanks to a series of inventions and innovations such as busbars and components for the construction of heavy-current switch cabinets. With its extensive market experience, EHRT is ideally placed to realize customer-specific requirements and identify crucial trends in near-real time.

The challenge

Wanted: A motor with specific characteristics

Several of EHRT’s key accounts were looking for CNC punching machines that are capable of punching round holes in flat copper material and forming threads inside them even faster, more economically and more flexibly than the systems already available in the market. The limiting factor which inhibited the further development of the proven machine concept was quickly pinpointed: no suitable standard motors existed as yet. They were all either too large or unable to deliver the specified torques. After searching for a while EHRT contacted WITTENSTEIN cyber motor. Within a very short time, the development teams at EHRT and WITTENSTEIN got together to design a drive solution for the SingleTap, as the built-in thread forming tool is known.

The solution

Developed: A frameless, bearingless and encoderless motor

The concept which has meanwhile been realized is based on a frameless motor belonging to the cyber® kit motor family. Both the rotor and the stator length and diameter were adapted absolutely flexibly to the mounting situation in the drive unit. The developers opted for a bearingless, encoderless design in order to reduce the overall height and simplify integration into the machine. They also gave preference to 560 VDC bus voltage over a 48 VDC power supply. The power supply unit not only develops less heat as a result – it is also much smaller. The length of the drive, too, is thus perfectly matched to the restricted installation space inside the punching machine.


The SingleTap allows process and quality parameters to be monitored and documented, so that appropriate action can be taken where necessary.


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WITTENSTEIN has the know-how and the tools to expertly assemble the motor and all the parts we supply.


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