New technology for sawing silicon, ceramics and semi-finished products dry and more quickly than ever
HK Präzisionstechnik GmbH presents a new diamond wire saw incorporating revolutionary sawing technology. A thin continuous wire guided via return rollers saws the hardest abrasive materials at very high speed. The saw works in dry operation, without cooling water. This allows you to cut material such as silicon blocks both quickly and safely. Thanks to the new technology developed by HK; the rapidly guided thin wire makes only line contact in the material. This prevents heating, and produces less waste. And because only low clamping forces are required, it is also possible to work sensitive materials or material combinations.
“The wire races round the rollers and through the material at about 180 km/h. Each individual diamond-impregnated segment makes contact with the material only very briefly and with great precision”, explained Xaver Mayer, Managing Director of HK Präzisionstechnik in Oberndorf. But at the same time, this canny engineer didn’t reveal the secret behind the technology quite so readily. Just this much: “We learned a lot from foresters and their sawing work”. And the company’s founder was also unwilling to disclose how they’d succeeded in joining the diamond wire to form a continuous loop in such a way that it can withstand the stresses produced. “That’s our know-how, which we developed here in house”.
Unimaginable speed and a high feed rate
The traditional use for a wire saw is to cut silicon blocks (ingots) into thin square or round wafers for the solar industry. Traditional saws and common belt saws work with cooling water or separating agents in wet operation. The relatively slow-moving belt, the large contact surface area and the long time in contact with the material mean that cooling is required. Often, this also involves an exchange of ions between the elements, which then requires complex additional work. At the same time, only relatively slow feed is possible. The new DDSM 500/1 saw from HK Präzisionstechnik is something completely different: It works in dry operation. The newly developed special wire is impregnated with fine diamond or CBN grains, and is formed into a continuous loop three and a half metres in length. It is guided via a system of deflection rollers, and can therefore work with a high cutting speed of up to 3,000 m/min or 180 km/h. This allows sawing at a high feed rate of over ten millimetres per minute. Since the wire, which is only 0.6 mm thick, makes only line contact at the side in the workpiece, this cutting method is also suitable for sensitive materials. The high cutting speed and the resulting low feed forces mean that minimal clamping forces are required.
Increased demand for solar cells promotes efficient sawing
The wire’s small cutting width also produces less waste. It becomes nowhere near as hot and the energy required is not as great, which means that the machine works with much greater energy efficiency. The bending processes on the deflection rollers and the centrifugal force arising from the high rotation speed mean that a self-cleaning process occurs on the cutting wire, which in turn results in a long service life. Various cutting materials, grain sizes and grain concentrations are available, depending on the application.
Due to the ever increasing need for solar cells, the company expects a lively demand for this efficient new cutting technology. The first users are very impressed. The new method can be used to cut not just silicon but also hard and soft material combinations such as rubber and steel, silicon carbite with aluminium sheathing, glass and silicone or rubber composite profiles. Composite materials of glass fibre / carbon fibre combinations, ceramics, PVC or thermoplastics and duroplastics can also be cut with the new dry sawing technology.
A long tradition of working for the best
HK Präzisionstechnik GmbH was founded in 1993 from the special equipment division of the world famous Heckler und Koch company. With a great depth of production and its own design and development department, the company manufactures hydraulic clamping fixtures and measuring systems for metalworking, which well-known machine manufacturers all over the world use in machining centres.
Convection ovens for the precise temperature control of thermoplastic composite materials and diamond wire saws for the high-precision cutting of very hard materials are the company’s other two pillars. The company also plans further future growth as a solution supplier with a high degree of design competence.