Presse

Witte:
„Bedded“ and “ Gripped “ on Ice

As a last resort the only way to clamp small fragile workpieces is by using ice as a vice.


The TKR company , who make special tools in the Western part of Germany has itself developed and produced fine-mechanical special tools, for the cable making technology .
With a know-how that has grown with years of experience and their ultra modern machines, TKR Gevelsberg, manufactures an extensive and specialized spectrum of parts. Also in the development of prototypes,
Preparation of small series fine-mechanical and special parts has secured this small company, with a team of 14 employees, a strong foothold in this segment of the market. Due to the ease in application and holding strength, complicated forms and shapes that are thin walled, no longer cause a headache when they need to be clamped.
Everyone can mill on a milling machine, the secret lies in clamping these parts, says company founder and manager Torsten Kreischer, smallest workpieces milled on his milling machine with a wall thickness down to 0,6mm. If the parts are flat, one uses the vacuum clamping technology.For clamping higher parts, the vacuum method is not satisfactory and also by conventional clamping means, like for example collet chucks, proved inadequate for these fine small worpieces.Therefore these tiny 3-D workpieces can only be clamped using very time consuming and costly methods such as for example by foundering moulds.

Using an innovative new clamping method these are a problem of the past. By freezing, workpieces can be held tension-free and precisely for workholding. "Ice-Vice clamping is the ideal technology, for clamping small thin-walled parts”, according to Kreischer, "although the workpieces are held securely during clamping there is no danger of damage to the parts when clamping or removing from the machine.
The system offered by the Witte company from Bleckede(Germany) was developed and manufactured by Lotsch Ltd. (Schwerte in Germany) consists of an aggregate for cooling down the include clamping plate. In this all in one cooling system the temperature can be regulated to within +/-2C°. For clamping the workpiece can be placed on the precooled plate; workpiece and clamping surface are moistened with a thin water film. Within seconds, the workpiece freezes to the clamping surface of the plate and lies absolutely plane. A constant temperature of -10 C° proved to be ideal for clamping.

As the workpiece is frozen to the plate on all sides, no vibration is experienced during the working/milling process so that a very high degree of precision can be achieved. After achieving the ideal temperature of –10C° a high degree of precision, approximately + / - 3 µm is reached. Workpieces with absolutely smooth, clean surfaces are produced without chattermarks. Smallest vibrations can make a very small workpiece completely useless, the Ice-Clamping opens up a whole new range of possibilities. While the small problem parts had to be prepared by TKR with much patience and time, the Ice-Vice plate is merely fixed onto the milling machine and work can start.

The plate can be milled to attain an optimal plan parallelism and already the clamping can begin.
Torsten Kreischer admitts that the Ice-Vice clamping system only covers a small area where it can be used, this amounts to about 8-10 percent of his needs. Without the availability of Ice-Vice most of these parts could not be clamped.
Torsten Kreischer explains, that he produces amongst others parts for the smallest manufactured steam-engine of the world that are produced in series. The Ice-Vice clamping especially suited for use with very small prefabricated and very thin-walled parts. Depending on the material, there are hardly any restrictions, it can clamp glass, quartz glass, plastic and even graphite, as well as most metallic materials. Before Kreischer worked with Ice-Vice, the 3D-workpieces had to be treated separately by means of using moulds and resins. Only after solidifying could the actual operation begin.