Technical Papers

Precision Turning and Grinding Machine

Innovative frequency converter to ensure efficient and flexible grinding processes

The proverbial Swiss precision not only extends to clock-making or pocket knife production. Exceptionally precise machine tools required for the production of high-quality products often come from the Jura region as well: Many renowned industry companies are resident there. One of them is Schaublin Machines SA. The company uses the frequency converter SD2S by SIEB & MEYER in their turning and grinding machines.


Schaublin Machines SA looks back on a long tradition: For almost a century now the company produces precision machines. With about 140 employees world wide, the Swiss experts profit from their great wealth of experience while simultaneously focusing on innovation. The portfolio ranges from conventional to CNC lathes and vertical machining centers. Precision is the top priority for all product developments – this feature has characterized the products of Schaublin Machines SA ever since. The quality standards are high - many customers have machines older than 60 years and they are still very satisfied with the performances of these machines.

One machine for grinding and turning

The high-precision machine tool 202 TG combines grinding and turning works and permits simultaneous use of up to eight CNC axes for processing. The machine features a cast frame, a W25 spindle stock and two slides (X/Z axis). Operators can use the same machine for grinding and turning. Of course, the machine can also be used for grinding applications only ‒ after all, the protective gear of the machine is especially adapted to this type of processing. Optionally, 202 TG comes with bar loader, chucks and a lot of other equipment. This way each machine can be adapted to the individual requirements of the customer. There are many fields of application. 202 TG is well-proven, for example, in the sectors automotive industry, optical industry, micromechanics, medical and dental technologies, aerospace industry and tool production.

During the development phase of 202 TG Schaublin searched the market for a suitable drive solution to operate the grinding spindles. The supplier of the spindles was decided beforehand – Meyrat, a company that has been cooperating with SIEB & MEYER for many years. Therefore, the solutions by Meyrat and SIEB & MEYER were optimally matched in the first place. Nevertheless, the company examined comparable systems of competitors, but these were not able to reach motor frequencies of up to 2,000 Hz.

Specialist for grinding applications

The decisive feature was, however, that SIEB & MEYER has developed SD2S especially for grinding applications. The system ensures low temperature rise even at maximum power so as to prevent excessive motor heating. This is not only beneficial for the sensitive materials of the machines but also for the machining quality. "When dimensioning a machine tool, the developers usually must consider a thermally conditioned material expansion due to increased rotor heating", says Rolf Gerhardt, director sales drive electronics at SIEB & MEYER. "But SD2S minimizes this effect and saves construction costs." Another advantage is the simple system integration according to the plug and play principle.

For grinding applications in particular, SD2S provides additional features: The device can save up to 64 parameter sets for different spindles. By means of coded connectors for the individual motor spindles, the frequency converter can detect the parameter set to be used for operation. The integrated technology functions for gap elimination allow sensitive monitoring of the spindle load based on the spindle current. The basis for the gap eliminator is the load indicator integrated in all SD2x devices, which provides extensive functions for detection and visualization. This increases the efficiency and flexibility of grinding machines significantly.

Living up to all expectations

Concerning the high motor frequencies, SD2S also meets the requirements: The solution permits the operation of synchronous and asynchronous motors up to a speed of 480,000 rpm (8,000 Hz). Depending on the application, SD2S can operate with or without a sensor. The connection with the higher-ranking control can be established via various options – interfaces for analog reference value signals (+/-10 V), digital I/Os, RS232 and USB as well as CAN bus are available. In addition, the SERVOLINK interface or an Anybus adapter permit the connection of PROFIBUS and EtherCAT.

Schaublin is very pleased with their decision because SD2S meets all the requirements and has a good price-performance ratio as well. In addition, the company Amptec represents SIEB & MEYER in Switzerland. The local presence and the focus on the customer make an intensive exchange of technical knowledge possible. The cooperation between the companies Schaublin, Amptec, Meyrat and SIEB & MEYER has proven successful.


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